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Table of Contents for Annals of Clinical Biochemistry. List of articles from both the latest and ahead of print issues.
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Standardising lipid testing and reporting in the United Kingdom; a joint statement by HEART UK and The Association for Laboratory Medicine
Annals of Clinical Biochemistry, Ahead of Print.
Atherosclerotic cardiovascular disease remains a major cause of premature death in the United Kingdom. Lipid testing is a key tool used to assess cardiovascular risk and guide clinical management decisions. There are currently no national guidelines to provide evidence-based recommendations on lipid testing and reporting for UK laboratories and clinicians. Here we present consensus guidance, following a review of published evidence by a multidisciplinary group of UK experts across a range of laboratory and clinical services. Recommendations include the composition of a standard lipid profile; indications for, and composition of, an enhanced lipid profile including apolipoprotein B and lipoprotein (a); use of the Sampson-NIH calculation for LDL-c estimation and guidance on when to flag abnormal results. This consensus guidance on lipid testing and reporting in the United Kingdom has been endorsed by HEART UK and The Association for Laboratory Medicine.
Atherosclerotic cardiovascular disease remains a major cause of premature death in the United Kingdom. Lipid testing is a key tool used to assess cardiovascular risk and guide clinical management decisions. There are currently no national guidelines to provide evidence-based recommendations on lipid testing and reporting for UK laboratories and clinicians. Here we present consensus guidance, following a review of published evidence by a multidisciplinary group of UK experts across a range of laboratory and clinical services. Recommendations include the composition of a standard lipid profile; indications for, and composition of, an enhanced lipid profile including apolipoprotein B and lipoprotein (a); use of the Sampson-NIH calculation for LDL-c estimation and guidance on when to flag abnormal results. This consensus guidance on lipid testing and reporting in the United Kingdom has been endorsed by HEART UK and The Association for Laboratory Medicine.
Biochemical osteomalacia in adults undergoing vitamin D testing in the North-East of Scotland
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundInternational guidelines give greatly varying definitions of 25-hydroxyvitamin D (25OHD) insufficiency and deficiency. Vitamin D testing is increasing despite 2016 UK guidance for adults advising routine vitamin D supplementation October-March and year-round for high risk groups. A service evaluation of vitamin D testing and biochemical osteomalacia in the North-East of Scotland (57–58°N) could inform definitions and testing guidance.MethodsWe identified adult 25OHD requests 8/7/2008–29/2/2020 and albumin-adjusted serum calcium (aCa), parathyroid hormone (PTH) and alkaline phosphatase (ALP) within 6 months of 25OHD testing. After excluding renal impairment and liver disease, we defined biochemical osteomalacia as ALP >130 IU/L and aCa <2.0 mmol/L and elevated PTH >9.2 or >6.8 pmol/L, depending on the assay. Possible biochemical osteomalacia was defined as 2 of these abnormalities in the absence of the third measurement. From these cases anonymised clinical data were then examined to confirm the diagnosis of osteomalacia.Results25,379 eligible patients had 25OHD measured: 25% were <25 nmol/L (6,258/25,379) and 18% <20 nmol/L (4,536/25,379). 0.5% (126/25,379) of eligible patients had biochemical or possible biochemical osteomalacia. After reviewing clinical records, only 0.1% (29/25,379) had clinically confirmed osteomalacia, equivalent to 2–3 cases/y for a population of 0.5 million, none of the untreated cases of clinically confirmed osteomalacia had 25OHD >25 nmol/L. For the entire tested population, when 25OHD was <25 nmol/L untreated osteomalacia confirmed by clinical records was rare (0.4%).ConclusionsOsteomalacia is rare in North-East Scotland. Our data call into question designating 25OHD 25–50 nmol/L ‘insufficiency’. The risk of osteomalacia even when 25OHD is <25 nmol/L is very low.
BackgroundInternational guidelines give greatly varying definitions of 25-hydroxyvitamin D (25OHD) insufficiency and deficiency. Vitamin D testing is increasing despite 2016 UK guidance for adults advising routine vitamin D supplementation October-March and year-round for high risk groups. A service evaluation of vitamin D testing and biochemical osteomalacia in the North-East of Scotland (57–58°N) could inform definitions and testing guidance.MethodsWe identified adult 25OHD requests 8/7/2008–29/2/2020 and albumin-adjusted serum calcium (aCa), parathyroid hormone (PTH) and alkaline phosphatase (ALP) within 6 months of 25OHD testing. After excluding renal impairment and liver disease, we defined biochemical osteomalacia as ALP >130 IU/L and aCa <2.0 mmol/L and elevated PTH >9.2 or >6.8 pmol/L, depending on the assay. Possible biochemical osteomalacia was defined as 2 of these abnormalities in the absence of the third measurement. From these cases anonymised clinical data were then examined to confirm the diagnosis of osteomalacia.Results25,379 eligible patients had 25OHD measured: 25% were <25 nmol/L (6,258/25,379) and 18% <20 nmol/L (4,536/25,379). 0.5% (126/25,379) of eligible patients had biochemical or possible biochemical osteomalacia. After reviewing clinical records, only 0.1% (29/25,379) had clinically confirmed osteomalacia, equivalent to 2–3 cases/y for a population of 0.5 million, none of the untreated cases of clinically confirmed osteomalacia had 25OHD >25 nmol/L. For the entire tested population, when 25OHD was <25 nmol/L untreated osteomalacia confirmed by clinical records was rare (0.4%).ConclusionsOsteomalacia is rare in North-East Scotland. Our data call into question designating 25OHD 25–50 nmol/L ‘insufficiency’. The risk of osteomalacia even when 25OHD is <25 nmol/L is very low.
The diagnostic and prognostic value of serum angiopoietin-like 4 level in neonatal respiratory distress syndrome
Annals of Clinical Biochemistry, Ahead of Print.
ObjectivesNeonatal respiratory distress syndrome (NRDS) is the most common respiratory disease in preterm infants (PIs). The implication of Angiopoietin-like 4 (ANGPTL4) was reported in lung diseases. We delved into the role of serum ANGPTL4 in NRDS diagnosis/prognosis.MethodsTotally 256 PIs were prospectively selected, including 128 NRDS infants and 128 non-NRDS PIs. NRDS infants were assigned into Survival and Death groups. ANGPTL4 level in PIs and its diagnostic and prognostic value for NRDS were separately assessed by ELISA and receiver operating characteristic curve. The independent risk factors (IRFs) for death in NRDS infants were analysed by multivariate logistic regression.ResultsNRDS infants exhibited reduced gestational age, birth weight, and 5 min Apgar score. ANGPTL4 level rose in NRDS infants, and increased with NRDS severity. Serum ANGPTL4 level was negatively correlated with 5 min Apgar score in NRDS infants. The area under the curve of serum ANGPTL4 for the diagnosis of NRDS was 0.902, with 88.28% sensitivity, 86.72% specificity, and 255.98 ng/mL cut-off value; the AUC for the diagnosis of severe NRDS was 0.741, with 66.67% sensitivity, 79.52% specificity, and 625.5 ng/mL cut-off value. Low gestational age, birth weight and 5 min Apgar score, severe NRDS, and elevated serum ANGPTL4 levels were IRFs for death in NRDS infants. NRDS infants with increased serum ANGPTL4 level displayed decreased survival rate and short survival time.ConclusionsANGPTL4 exhibited high diagnostic value and predictive value for death in NRDS, and it served as a biomarker for the diagnosis and prognosis of NRDS.
ObjectivesNeonatal respiratory distress syndrome (NRDS) is the most common respiratory disease in preterm infants (PIs). The implication of Angiopoietin-like 4 (ANGPTL4) was reported in lung diseases. We delved into the role of serum ANGPTL4 in NRDS diagnosis/prognosis.MethodsTotally 256 PIs were prospectively selected, including 128 NRDS infants and 128 non-NRDS PIs. NRDS infants were assigned into Survival and Death groups. ANGPTL4 level in PIs and its diagnostic and prognostic value for NRDS were separately assessed by ELISA and receiver operating characteristic curve. The independent risk factors (IRFs) for death in NRDS infants were analysed by multivariate logistic regression.ResultsNRDS infants exhibited reduced gestational age, birth weight, and 5 min Apgar score. ANGPTL4 level rose in NRDS infants, and increased with NRDS severity. Serum ANGPTL4 level was negatively correlated with 5 min Apgar score in NRDS infants. The area under the curve of serum ANGPTL4 for the diagnosis of NRDS was 0.902, with 88.28% sensitivity, 86.72% specificity, and 255.98 ng/mL cut-off value; the AUC for the diagnosis of severe NRDS was 0.741, with 66.67% sensitivity, 79.52% specificity, and 625.5 ng/mL cut-off value. Low gestational age, birth weight and 5 min Apgar score, severe NRDS, and elevated serum ANGPTL4 levels were IRFs for death in NRDS infants. NRDS infants with increased serum ANGPTL4 level displayed decreased survival rate and short survival time.ConclusionsANGPTL4 exhibited high diagnostic value and predictive value for death in NRDS, and it served as a biomarker for the diagnosis and prognosis of NRDS.
The use of peripheral blood biomarkers for predicting the risk of immune-related adverse events in immune checkpoint inhibitor therapy
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundImmune checkpoint inhibitors (ICIs) have revolutionised oncology care, by enhancing the body’s T cell lymphocyte response against tumour cells. ICIs block the inhibitory signalling between tumour cells and the immune system, but consequently reduce immunological tolerance. Subsequently for some, this leads to immune-related adverse events (irAE), a spectrum term for autoimmune-like toxicities induced by ICIs that affects various tissues and organs. This limited narrative review will give a brief overview of immune checkpoint inhibitors and immune-related adverse events for laboratory professionals and review the current evidence for predictive biomarkers.MethodsA limited narrative review was conducted by accessing Pubmed and Google from June 2023 to January 2024 to identify references published from database inception to January 2024. Language was restricted to English.Results/findingsProfessional guidance does not recommend any biomarkers for irAE prediction. Some studies have found an association between the prediction of irAE and interleukin six (IL-6), C-reactive protein (CRP), thyroid stimulating hormone (TSH), albumin, ferritin, full blood count metrics, and lactate dehydrogenase (LDH). However, these have often been single-centre retrospective studies. While an abundance of societal guidance has been produced, it is unclear what blood tests should be included within a baseline profile.ConclusionsPresently, there is no singular biomarker routinely available in clinical laboratories that can predict the onset of irAE. A custom battery of tests may be more predictive, but evidence is currently lacking. In the meantime, due to the clinical significance of these complications, laboratory professionals should proactively support prospective studies.
BackgroundImmune checkpoint inhibitors (ICIs) have revolutionised oncology care, by enhancing the body’s T cell lymphocyte response against tumour cells. ICIs block the inhibitory signalling between tumour cells and the immune system, but consequently reduce immunological tolerance. Subsequently for some, this leads to immune-related adverse events (irAE), a spectrum term for autoimmune-like toxicities induced by ICIs that affects various tissues and organs. This limited narrative review will give a brief overview of immune checkpoint inhibitors and immune-related adverse events for laboratory professionals and review the current evidence for predictive biomarkers.MethodsA limited narrative review was conducted by accessing Pubmed and Google from June 2023 to January 2024 to identify references published from database inception to January 2024. Language was restricted to English.Results/findingsProfessional guidance does not recommend any biomarkers for irAE prediction. Some studies have found an association between the prediction of irAE and interleukin six (IL-6), C-reactive protein (CRP), thyroid stimulating hormone (TSH), albumin, ferritin, full blood count metrics, and lactate dehydrogenase (LDH). However, these have often been single-centre retrospective studies. While an abundance of societal guidance has been produced, it is unclear what blood tests should be included within a baseline profile.ConclusionsPresently, there is no singular biomarker routinely available in clinical laboratories that can predict the onset of irAE. A custom battery of tests may be more predictive, but evidence is currently lacking. In the meantime, due to the clinical significance of these complications, laboratory professionals should proactively support prospective studies.
Biological variation data: An important old topic with new standards and new look resources
Annals of Clinical Biochemistry, Ahead of Print.
Folic and folinic acid load tests for dynamic assessments of compliance and metabolism in folate deficiency and hyperhomocysteinaemia patients unresponsive to high-dose folate replacement
Annals of Clinical Biochemistry, Ahead of Print.
We describe the utility of ‘folic and folinic acid load tests’ in the investigation of a 26-year-old woman with persistently low serum folate and moderate hyperhomocysteinaemia unresponsive to folic acid supplements. Serum folate, plasma 5-methyltetrahydrofolate (5-MTHF), red cell 5-MTHF and plasma total homocysteine at baseline, 2-h, 4-h and 2- or 4-days (if applicable) post administration of a large dose of oral folic acid, or oral or parenteral folinic acid were measured. The tests confirmed non-compliance but also suggested an unsuspected possible defect in the folate pathway based on differential response to folic versus folinic acid supplements. The folic and folinic acid load tests identify non-compliance and can help identify possible defects related to the absorption, transportation, or metabolism of folate.
We describe the utility of ‘folic and folinic acid load tests’ in the investigation of a 26-year-old woman with persistently low serum folate and moderate hyperhomocysteinaemia unresponsive to folic acid supplements. Serum folate, plasma 5-methyltetrahydrofolate (5-MTHF), red cell 5-MTHF and plasma total homocysteine at baseline, 2-h, 4-h and 2- or 4-days (if applicable) post administration of a large dose of oral folic acid, or oral or parenteral folinic acid were measured. The tests confirmed non-compliance but also suggested an unsuspected possible defect in the folate pathway based on differential response to folic versus folinic acid supplements. The folic and folinic acid load tests identify non-compliance and can help identify possible defects related to the absorption, transportation, or metabolism of folate.
Benchtop centrifugation: An effective method for reducing lipaemia associated interference in grossly lipaemic samples?
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundGrossly lipaemic samples are a significant cause of analytical errors, potentially impacting patient care. The causes of lipaemia are varied and often unavoidable, while methods to reduce lipaemia through gold-standard ultracentrifugation are limited by availability, transportation and cost. Benchtop centrifugation has been proposed as an alternative method to reduce lipaemia.MethodsFifty-three grossly lipaemic serum samples (lipaemia >201.8 mg/dL) that were unsuitable for analysis were selected and centrifugated at 18840 g for different time-periods with lipaemia measured prior to and after centrifugation. Core analytes were measured on serum samples free of lipaemia before and after 30 min of centrifugation at 18840 g to assess the effect of the centrifugation process.ResultsAfter centrifugation for 5 min, 90% of grossly lipaemic samples were either ideal (lipaemia <50 mg/dL) or adequate (lipaemia 50.1–201.7 mg/dL) for analyte testing. All samples were either adequate or ideal for testing following centrifugation for 30 min. Although some analytes showed a statistically significant change in the measured concentration post high-speed centrifugation, none had clinically significant changes according to analyte specific reference change value (RCV) analysis. Aspartate aminotransferase (AST) and creatine kinase (CK) demonstrated the most notable reductions in activity, but these did not exceed their RCV.ConclusionsBenchtop centrifugation shows potential laboratory utility in reducing lipaemia whilst maintaining clinically reliable results, however small sample sizes preclude firm conclusions. Further research is warranted to increase the sample size with finer time-point tuning, sub-group analysis and temperature analysis, due to the potential for sample heat injury, to balance practicality and accuracy.
BackgroundGrossly lipaemic samples are a significant cause of analytical errors, potentially impacting patient care. The causes of lipaemia are varied and often unavoidable, while methods to reduce lipaemia through gold-standard ultracentrifugation are limited by availability, transportation and cost. Benchtop centrifugation has been proposed as an alternative method to reduce lipaemia.MethodsFifty-three grossly lipaemic serum samples (lipaemia >201.8 mg/dL) that were unsuitable for analysis were selected and centrifugated at 18840 g for different time-periods with lipaemia measured prior to and after centrifugation. Core analytes were measured on serum samples free of lipaemia before and after 30 min of centrifugation at 18840 g to assess the effect of the centrifugation process.ResultsAfter centrifugation for 5 min, 90% of grossly lipaemic samples were either ideal (lipaemia <50 mg/dL) or adequate (lipaemia 50.1–201.7 mg/dL) for analyte testing. All samples were either adequate or ideal for testing following centrifugation for 30 min. Although some analytes showed a statistically significant change in the measured concentration post high-speed centrifugation, none had clinically significant changes according to analyte specific reference change value (RCV) analysis. Aspartate aminotransferase (AST) and creatine kinase (CK) demonstrated the most notable reductions in activity, but these did not exceed their RCV.ConclusionsBenchtop centrifugation shows potential laboratory utility in reducing lipaemia whilst maintaining clinically reliable results, however small sample sizes preclude firm conclusions. Further research is warranted to increase the sample size with finer time-point tuning, sub-group analysis and temperature analysis, due to the potential for sample heat injury, to balance practicality and accuracy.
Measurement of uric acid in FC Mix tubes is not accurate
Annals of Clinical Biochemistry, Ahead of Print.
Elevated Vitamin D leading to an Incidental Diagnosis of Multiple Myeloma
Annals of Clinical Biochemistry, Ahead of Print.
A case involving the incidental diagnosis of multiple myeloma (MM) due to interference in the 25-hydroxy-vitamin D (25(OH) vitamin D) immunoassay is presented. The patient, under the care of rheumatology and receiving treatment with alendronic acid and vitamin D supplements, was referred to endocrinology for investigation of acromegaly. Acromegaly was subsequently ruled out; however, during the investigations, consistently elevated levels of 25(OH) vitamin D were noted, raising suspicion of vitamin D resistance syndrome. The laboratory and endocrinology teams engaged in discussions, and following the cessation of medication, repeated analyses for 25(OH) vitamin D and a single analysis of 1,25-dihydroxy-vitamin D levels were requested, yielding high and normal results, respectively. The laboratory conducted a three-step interference investigation, ultimately identifying a high molecular weight molecule responsible for the initially elevated 25(OH) vitamin D levels. Due to the clinical presentation of back pain, a proteinogram was requested, revealing a monoclonal band of 36 g/L. Subsequent free light chain analysis indicated an elevated ratio. With three risk factors identified, this was classified as an established MM and urgently referred to haematology for correct management. Laboratory assay interferences have the potential to disrupt the accurate diagnostic workup of patients. Collaborative discussions between laboratory and clinical teams regarding such cases aid in directing the diagnostic pathway appropriately, facilitating prompt and proper diagnosis and management.
A case involving the incidental diagnosis of multiple myeloma (MM) due to interference in the 25-hydroxy-vitamin D (25(OH) vitamin D) immunoassay is presented. The patient, under the care of rheumatology and receiving treatment with alendronic acid and vitamin D supplements, was referred to endocrinology for investigation of acromegaly. Acromegaly was subsequently ruled out; however, during the investigations, consistently elevated levels of 25(OH) vitamin D were noted, raising suspicion of vitamin D resistance syndrome. The laboratory and endocrinology teams engaged in discussions, and following the cessation of medication, repeated analyses for 25(OH) vitamin D and a single analysis of 1,25-dihydroxy-vitamin D levels were requested, yielding high and normal results, respectively. The laboratory conducted a three-step interference investigation, ultimately identifying a high molecular weight molecule responsible for the initially elevated 25(OH) vitamin D levels. Due to the clinical presentation of back pain, a proteinogram was requested, revealing a monoclonal band of 36 g/L. Subsequent free light chain analysis indicated an elevated ratio. With three risk factors identified, this was classified as an established MM and urgently referred to haematology for correct management. Laboratory assay interferences have the potential to disrupt the accurate diagnostic workup of patients. Collaborative discussions between laboratory and clinical teams regarding such cases aid in directing the diagnostic pathway appropriately, facilitating prompt and proper diagnosis and management.
Exploratory study on reference intervals of calprotectin and pentraxin 3
Annals of Clinical Biochemistry, Ahead of Print.
IntroductionThe aim of our study was to determine reference intervals for serum pentraxin 3 and calprotectin, as well as for urine calprotectin according to the CLSI EP28-A3C guidelines for defining, establishing, and verifying reference intervals in the clinical laboratory.Materials and methodsA total of 120 serum and urine samples from either healthy volunteers or outpatients were used for reference interval establishment. The participants had CRP levels, leucocyte counts, serum urea levels, creatinine levels, and estimated glomerular filtration rates (CKD-EPI eGFRs) within the reference range and no medical history of acute/chronic inflammatory diseases/conditions or cancer. Calprotectin was measured via a commercially available turbidimetric method – the Bühhlmann fCAL® Turbo Reagent Kit – while pentraxin 3 was measured using the Human Pentraxin 3 ELISA Kit from the BioVendor Group.ResultsThe serum calprotectin reference range was ≤3.6 mg/L, the 90% CI for the upper reference range was 3.1–4.1 mg/L, while the serum pentraxin 3 reference concentration was ≤3.0 µg/L, and the 90% CI for the upper reference range being 2.7–3.2 µg/L. Additionally, the urinary calprotectin concentration was ≤1.4 mg/L, with a 90% CI for the upper reference range of 1.0–1.7 mg/L.ConclusionThis study reports sample and method-specific reference intervals for the detection of various inflammatory conditions.
IntroductionThe aim of our study was to determine reference intervals for serum pentraxin 3 and calprotectin, as well as for urine calprotectin according to the CLSI EP28-A3C guidelines for defining, establishing, and verifying reference intervals in the clinical laboratory.Materials and methodsA total of 120 serum and urine samples from either healthy volunteers or outpatients were used for reference interval establishment. The participants had CRP levels, leucocyte counts, serum urea levels, creatinine levels, and estimated glomerular filtration rates (CKD-EPI eGFRs) within the reference range and no medical history of acute/chronic inflammatory diseases/conditions or cancer. Calprotectin was measured via a commercially available turbidimetric method – the Bühhlmann fCAL® Turbo Reagent Kit – while pentraxin 3 was measured using the Human Pentraxin 3 ELISA Kit from the BioVendor Group.ResultsThe serum calprotectin reference range was ≤3.6 mg/L, the 90% CI for the upper reference range was 3.1–4.1 mg/L, while the serum pentraxin 3 reference concentration was ≤3.0 µg/L, and the 90% CI for the upper reference range being 2.7–3.2 µg/L. Additionally, the urinary calprotectin concentration was ≤1.4 mg/L, with a 90% CI for the upper reference range of 1.0–1.7 mg/L.ConclusionThis study reports sample and method-specific reference intervals for the detection of various inflammatory conditions.
Interference in immunoassay: An estimate based on “real-world” experience. (Reply)
Annals of Clinical Biochemistry, Ahead of Print.
Interference in immunoassay
Annals of Clinical Biochemistry, Ahead of Print.
Establishment of sex-specific reference intervals for PIVKA-II in Southwest China: A real-world data analysis
Annals of Clinical Biochemistry, Ahead of Print.
ObjectiveWe aim to establish the sex-related reference intervals (RIs) of PIVKA-II in southwest China by indirect method with the real-world data.MethodsBetween 29 July 2016 and 5 February 2024, PIVKA-II test data were collected from 120,780 healthy adult participants (aged 18 to 97 years) in the Laboratory Information System (LIS) of West China Hospital to establish reference intervals. Additionally, a validation group comprised of 2068 healthy adults was evaluated using the same detection algorithm and platform. Following the CLSI EP28-A3 guideline, Box-Cox transformation was applied for normal transformation, and outliers were identified using the Tukey method. Furthermore, we employed the standard normal deviate test (z-test) recommended by Harris and Boyd to determine whether to stratify reference intervals by age and sex subclasses.ResultsWe successfully established population-specific RI for PIVKA-II in southwest China using an indirect method. By utilizing a robust dataset and conducting rigorous statistical analyses, we delineated sex-specific RIs, with values of 0–35 mAU/mL for males and 0–29 mAU/mL for females according to the normal distribution method, and 0–32 mAU/mL for males and 0–28 mAU/mL for females using the non-parametric method. These intervals are more suitable for the local population than those derived from manual methods.ConclusionThese RIs provide valuable guidance for the accurate interpretation of PIVKA-II levels in the local population.
ObjectiveWe aim to establish the sex-related reference intervals (RIs) of PIVKA-II in southwest China by indirect method with the real-world data.MethodsBetween 29 July 2016 and 5 February 2024, PIVKA-II test data were collected from 120,780 healthy adult participants (aged 18 to 97 years) in the Laboratory Information System (LIS) of West China Hospital to establish reference intervals. Additionally, a validation group comprised of 2068 healthy adults was evaluated using the same detection algorithm and platform. Following the CLSI EP28-A3 guideline, Box-Cox transformation was applied for normal transformation, and outliers were identified using the Tukey method. Furthermore, we employed the standard normal deviate test (z-test) recommended by Harris and Boyd to determine whether to stratify reference intervals by age and sex subclasses.ResultsWe successfully established population-specific RI for PIVKA-II in southwest China using an indirect method. By utilizing a robust dataset and conducting rigorous statistical analyses, we delineated sex-specific RIs, with values of 0–35 mAU/mL for males and 0–29 mAU/mL for females according to the normal distribution method, and 0–32 mAU/mL for males and 0–28 mAU/mL for females using the non-parametric method. These intervals are more suitable for the local population than those derived from manual methods.ConclusionThese RIs provide valuable guidance for the accurate interpretation of PIVKA-II levels in the local population.
Establishment of reference intervals for estimated glomerular filtration rate in apparently healthy adults based on the full age spectrum equation: A single-centre study
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundIdentifying gender and age-related eGFR trends is crucial for precise renal function assessment. This study aims to analyse eGFR distribution with the full age spectrum (FAS) equation and establish reference intervals based on gender and age in a single-centre cohort.MethodsFollowing the inclusion and exclusion criteria outlined in this study, a total of 24,024 reference individuals were ultimately selected. Using the approach recommended by the CLSI C28-A3 guidelines, we assessed the distribution of eGFR across different gender and age groups. The two-sided nonparametric method (P2.5–P97.5) was applied to establish the eGFR reference intervals for a healthy Chinese population.ResultsThe eGFR levels in healthy adults exhibited a non-normally distributed pattern. Notably, there were significant differences in eGFR levels between males and females, with females showing a notably higher eGFR level than males. Additionally, eGFR levels demonstrated significant variations across different age groups within both male and female cohorts. As age increased, eGFR showed a significant decline, except in individuals aged 20–29 and 30–39 years. Therefore, reference intervals for eGFR were created based on both gender and age.ConclusionsWe established the reference interval for eGFR using the FAS equation, drawing from a large sample population at a single centre. This establishes a potential framework for evaluating renal function in healthy individuals and for diagnosing and treating kidney-related diseases.
BackgroundIdentifying gender and age-related eGFR trends is crucial for precise renal function assessment. This study aims to analyse eGFR distribution with the full age spectrum (FAS) equation and establish reference intervals based on gender and age in a single-centre cohort.MethodsFollowing the inclusion and exclusion criteria outlined in this study, a total of 24,024 reference individuals were ultimately selected. Using the approach recommended by the CLSI C28-A3 guidelines, we assessed the distribution of eGFR across different gender and age groups. The two-sided nonparametric method (P2.5–P97.5) was applied to establish the eGFR reference intervals for a healthy Chinese population.ResultsThe eGFR levels in healthy adults exhibited a non-normally distributed pattern. Notably, there were significant differences in eGFR levels between males and females, with females showing a notably higher eGFR level than males. Additionally, eGFR levels demonstrated significant variations across different age groups within both male and female cohorts. As age increased, eGFR showed a significant decline, except in individuals aged 20–29 and 30–39 years. Therefore, reference intervals for eGFR were created based on both gender and age.ConclusionsWe established the reference interval for eGFR using the FAS equation, drawing from a large sample population at a single centre. This establishes a potential framework for evaluating renal function in healthy individuals and for diagnosing and treating kidney-related diseases.
Decreased serum SLC7A11 and GPX4 levels may reflect disease severity of acute ischaemic stroke
Annals of Clinical Biochemistry, Ahead of Print.
ObjectiveThis study aimed to examine the levels of solute carrier family seven number 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in the serum of patients with acute ischaemic stroke (AIS) and their relationship with disease severity.MethodsA total of 148 patients with AIS together with 148 healthy controls (HCs) were enrolled. The expression levels of SLC7A11 and GPX4 in serum were detected immediately as early as possible. Radiographic severity was detected by Alberta Stroke Program Early CT Score (ASPECTS). Disease severity was evaluated using modified Rankin Scale (mRS). High-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-9 (MMP-9) expression levels were also measured. A correlation analysis was conducted to determine the relationship between the expression levels of SLC7A11 and GPX4 with the clinical severity of the disease and the levels of hs-CRP and MMP-9. Furthermore, receiver operating characteristic (ROC) curve analysis was utilized to assess the potential of SLC7A11 and GPX4 as diagnostic markers.ResultsCompared to the HC group, the serum expression levels of SLC7A11 and GPX4 were significantly lower in the AIS group. Serum SLC7A11 levels were positively associated with serum GPX4 levels. The AIS group included 50 patients with mild neurological impairment, 52 with moderate neurological impairment, and 46 with severe neurological impairment. AIS patients with mild neurological impairment had drastically higher serum SLC7A11 and GPX4 levels compared with those with moderate neurological impairment. AIS patients with moderate neurological impairment showed significantly higher serum SLC7A11 and GPX4 concentrations compared with those with severe neurological impairment. ROC curve analysis demonstrated that both serum SLC7A11 and GPX4 may both act as potential indicators for evaluating of AIS disease severity. In addition, both serum SLC7A11 and GPX4 levels were positively correlated with ASPECTS. Both serum SLC7A11 and GPX4 levels were negatively associated with hs-CRP as well as MMP-9 levels. Serum SLC7A11 and GPX4 levels were significantly increased following comprehensive therapy.ConclusionsDecreased SLC7A11 and GPX4 levels may reflect disease severity of AIS.
ObjectiveThis study aimed to examine the levels of solute carrier family seven number 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in the serum of patients with acute ischaemic stroke (AIS) and their relationship with disease severity.MethodsA total of 148 patients with AIS together with 148 healthy controls (HCs) were enrolled. The expression levels of SLC7A11 and GPX4 in serum were detected immediately as early as possible. Radiographic severity was detected by Alberta Stroke Program Early CT Score (ASPECTS). Disease severity was evaluated using modified Rankin Scale (mRS). High-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-9 (MMP-9) expression levels were also measured. A correlation analysis was conducted to determine the relationship between the expression levels of SLC7A11 and GPX4 with the clinical severity of the disease and the levels of hs-CRP and MMP-9. Furthermore, receiver operating characteristic (ROC) curve analysis was utilized to assess the potential of SLC7A11 and GPX4 as diagnostic markers.ResultsCompared to the HC group, the serum expression levels of SLC7A11 and GPX4 were significantly lower in the AIS group. Serum SLC7A11 levels were positively associated with serum GPX4 levels. The AIS group included 50 patients with mild neurological impairment, 52 with moderate neurological impairment, and 46 with severe neurological impairment. AIS patients with mild neurological impairment had drastically higher serum SLC7A11 and GPX4 levels compared with those with moderate neurological impairment. AIS patients with moderate neurological impairment showed significantly higher serum SLC7A11 and GPX4 concentrations compared with those with severe neurological impairment. ROC curve analysis demonstrated that both serum SLC7A11 and GPX4 may both act as potential indicators for evaluating of AIS disease severity. In addition, both serum SLC7A11 and GPX4 levels were positively correlated with ASPECTS. Both serum SLC7A11 and GPX4 levels were negatively associated with hs-CRP as well as MMP-9 levels. Serum SLC7A11 and GPX4 levels were significantly increased following comprehensive therapy.ConclusionsDecreased SLC7A11 and GPX4 levels may reflect disease severity of AIS.
The variability of measured and calculated low-density lipoprotein (LDL) cholesterol in statin-treated diabetes patients
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundThe Sampson-NIH and Martin-Hopkins low-density lipoprotein cholesterol (LDL-C) equations are advocated as being superior to the Friedewald calculation. However, their mathematical complexity means they may have different biological and analytical variation when tracking LDL-C in the same patient. This study has established the biological variation (BV) of calculated and directly measured LDL-C (dLDL-C) in patients taking equivalent doses of a long (atorvastatin) and short (simvastatin) half-life statin. It also modelled how analytical imprecision might add to these BVs.MethodsIn a crossover study of lipid BV involving 26 patients with type 2 diabetes (T2DM) initially taking either simvastatin 40 mg or atorvastatin 10 mg, fasting lipids were measured 10 times over 5 weeks after a 3 month run-in. The same procedure was then followed for the alternate statin. Outlier removal and CV-ANOVA established the BV of dLDL and each formula. Analytical measurement uncertainty was estimated from 6 months of real-world data.ResultsThe intra-individual BV of dLDL-C measurement was considerably lower with atorvastatin than simvastatin (CV 1.3%(95% CI 1.1–1.5%) vs. 11.1%(10.2–12.2%), respectively). No equation could distinguish this difference (Friedewald 11.0%(95% CI 10.0–12.1%) vs. 12.9%(11.8–14.2%), Sampson-NIH 10.4%(9.5–11.5%) vs. 11.7% (10.7–12.8%) and Martin-Hopkins 9.3%(8.5–10.3%) vs. 11.3%(10.3–12.4%)). Real-world analytical CVs were 2.6% (Sampson-NIH), 2.6% (Martin-Hopkins) 2.8% (Friedewald) and 2.0% (dLDL-C).ConclusionsInherent biological LDL-C variability using these formulae is substantially greater than direct measurement in T2DM patients taking atorvastatin. Typical analytical imprecision was also greater. Together, this may fundamentally limit these equations’ ability to track true LDL-C changes in patients taking popular statin treatments.
BackgroundThe Sampson-NIH and Martin-Hopkins low-density lipoprotein cholesterol (LDL-C) equations are advocated as being superior to the Friedewald calculation. However, their mathematical complexity means they may have different biological and analytical variation when tracking LDL-C in the same patient. This study has established the biological variation (BV) of calculated and directly measured LDL-C (dLDL-C) in patients taking equivalent doses of a long (atorvastatin) and short (simvastatin) half-life statin. It also modelled how analytical imprecision might add to these BVs.MethodsIn a crossover study of lipid BV involving 26 patients with type 2 diabetes (T2DM) initially taking either simvastatin 40 mg or atorvastatin 10 mg, fasting lipids were measured 10 times over 5 weeks after a 3 month run-in. The same procedure was then followed for the alternate statin. Outlier removal and CV-ANOVA established the BV of dLDL and each formula. Analytical measurement uncertainty was estimated from 6 months of real-world data.ResultsThe intra-individual BV of dLDL-C measurement was considerably lower with atorvastatin than simvastatin (CV 1.3%(95% CI 1.1–1.5%) vs. 11.1%(10.2–12.2%), respectively). No equation could distinguish this difference (Friedewald 11.0%(95% CI 10.0–12.1%) vs. 12.9%(11.8–14.2%), Sampson-NIH 10.4%(9.5–11.5%) vs. 11.7% (10.7–12.8%) and Martin-Hopkins 9.3%(8.5–10.3%) vs. 11.3%(10.3–12.4%)). Real-world analytical CVs were 2.6% (Sampson-NIH), 2.6% (Martin-Hopkins) 2.8% (Friedewald) and 2.0% (dLDL-C).ConclusionsInherent biological LDL-C variability using these formulae is substantially greater than direct measurement in T2DM patients taking atorvastatin. Typical analytical imprecision was also greater. Together, this may fundamentally limit these equations’ ability to track true LDL-C changes in patients taking popular statin treatments.
Coefficients of variation analyses of internal quality control status for blood lead in China from 2015 to 2023
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundBlood lead test is widely conducted in Chinese laboratories, while the imprecision of blood lead measurement based on internal quality control (IQC) across China has not been comprehensively evaluated nowadays.MethodsUsing the IQC data of blood lead collected through a web-based external quality assessment (EQA) reporting system, we analysed current coefficients of variation (CVs) of blood lead from 2015 to 2023 among Chinese laboratories. Two allowable total error (TEa) imprecision levels from EQA were applied to calculate the pass rates, namely percentages of laboratories meeting precision quality specifications. Besides, CV values and pass rates by different subgroups were further performed to assess potential differences.ResultsGenerally, median CV values significantly declined year by year from 6.8% in February 2015 to 5.9% in March 2023. The pass rates based on 1/3 TEa showed upward trends increasing from 15.3% in February 2015 to 20.0% in March 2023, but these percentages were non-ideal with less than 25%. No significant differences in CVs were found between tertiary hospitals and non-tertiary hospitals and between accredited and non-accredited laboratories. Significant time trends were observed in tertiary hospitals and non-accredited laboratories. As for manufacturers, Bohui and self-made QC sample were most widely used with obvious interannual declining trends of CVs.ConclusionsThe CVs of blood lead demonstrated continuous overall improvements in the past twenty years. However, relatively lower pass rates indicated the non-ideal imprecision performance, and more proper performance specifications are warranted. Thus, imprecision improvement and ongoing investigation for blood lead IQC are still needed.
BackgroundBlood lead test is widely conducted in Chinese laboratories, while the imprecision of blood lead measurement based on internal quality control (IQC) across China has not been comprehensively evaluated nowadays.MethodsUsing the IQC data of blood lead collected through a web-based external quality assessment (EQA) reporting system, we analysed current coefficients of variation (CVs) of blood lead from 2015 to 2023 among Chinese laboratories. Two allowable total error (TEa) imprecision levels from EQA were applied to calculate the pass rates, namely percentages of laboratories meeting precision quality specifications. Besides, CV values and pass rates by different subgroups were further performed to assess potential differences.ResultsGenerally, median CV values significantly declined year by year from 6.8% in February 2015 to 5.9% in March 2023. The pass rates based on 1/3 TEa showed upward trends increasing from 15.3% in February 2015 to 20.0% in March 2023, but these percentages were non-ideal with less than 25%. No significant differences in CVs were found between tertiary hospitals and non-tertiary hospitals and between accredited and non-accredited laboratories. Significant time trends were observed in tertiary hospitals and non-accredited laboratories. As for manufacturers, Bohui and self-made QC sample were most widely used with obvious interannual declining trends of CVs.ConclusionsThe CVs of blood lead demonstrated continuous overall improvements in the past twenty years. However, relatively lower pass rates indicated the non-ideal imprecision performance, and more proper performance specifications are warranted. Thus, imprecision improvement and ongoing investigation for blood lead IQC are still needed.
The effects of controlled acute psychological stress on serum cortisol and plasma metanephrine concentrations in healthy subjects
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundAs cortisol and metanephrine are involved in the stress response, it is often recommended that individuals are relaxed at the time of venepuncture, however, evidence behind these recommendations is lacking. We investigated the effects of acute psychological stress on serum cortisol and plasma metanephrine concentrations in healthy individuals exposed to varying levels of psychological stress and compared these results to self-reported measures of stress.MethodsTen medical students completed two medical in-person simulations (one low-complexity, one high-complexity) in a random order. At four times, participants completed the State-Trait Anxiety Inventory (STAI) and serum cortisol and plasma metanephrine/normetanephrine were tested.ResultsMedian (interquartile range) STAI prior to the low-complexity simulation was 44 (18) versus 33 (13) afterwards (P = 0.050). STAI prior to the high-complexity simulation was 33 (10) versus 48 (17) afterwards (P = 0.007). Cortisol prior to the low-complexity simulation was 272 nmol/L (115) versus 247 (115) afterwards (P = 0.333). Prior to the high-complexity simulation, cortisol was 246 (70) versus 261 (137) afterwards (P = 0.859). Metanephrine prior to the low-complexity simulation was 242 pmol/L (79) versus 247 (93) afterwards (P = 0.515). Metanephrine prior to the high-complexity simulation was 220 (81) versus 251 pmol/L (120) afterwards (P = 0.074). Normetanephrine prior to the low-complexity simulation was 593 pmol/L (247) versus 682 (281) afterwards (P = 0.047 for the difference). Normetanephrine prior to the high-complexity simulation was 696 (123) versus 705 pmol/L (224) afterwards (P = 0.169).ConclusionsThe trend in cortisol levels largely reflected changes in STAI. We outline some implications of these findings for current practice and future research.
BackgroundAs cortisol and metanephrine are involved in the stress response, it is often recommended that individuals are relaxed at the time of venepuncture, however, evidence behind these recommendations is lacking. We investigated the effects of acute psychological stress on serum cortisol and plasma metanephrine concentrations in healthy individuals exposed to varying levels of psychological stress and compared these results to self-reported measures of stress.MethodsTen medical students completed two medical in-person simulations (one low-complexity, one high-complexity) in a random order. At four times, participants completed the State-Trait Anxiety Inventory (STAI) and serum cortisol and plasma metanephrine/normetanephrine were tested.ResultsMedian (interquartile range) STAI prior to the low-complexity simulation was 44 (18) versus 33 (13) afterwards (P = 0.050). STAI prior to the high-complexity simulation was 33 (10) versus 48 (17) afterwards (P = 0.007). Cortisol prior to the low-complexity simulation was 272 nmol/L (115) versus 247 (115) afterwards (P = 0.333). Prior to the high-complexity simulation, cortisol was 246 (70) versus 261 (137) afterwards (P = 0.859). Metanephrine prior to the low-complexity simulation was 242 pmol/L (79) versus 247 (93) afterwards (P = 0.515). Metanephrine prior to the high-complexity simulation was 220 (81) versus 251 pmol/L (120) afterwards (P = 0.074). Normetanephrine prior to the low-complexity simulation was 593 pmol/L (247) versus 682 (281) afterwards (P = 0.047 for the difference). Normetanephrine prior to the high-complexity simulation was 696 (123) versus 705 pmol/L (224) afterwards (P = 0.169).ConclusionsThe trend in cortisol levels largely reflected changes in STAI. We outline some implications of these findings for current practice and future research.
Simultaneous quantification of serum symmetric dimethylarginine, asymmetric dimethylarginine and creatinine for use in a routine clinical laboratory
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundSymmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA) are naturally occurring amino acids classed as uraemic toxins by the European Uremic Toxins Work Group. SDMA is principally excreted through the kidneys and is a well-known renal function marker, and ADMA is a potent inhibitor of nitric oxide production. Here, we describe the development of a rapid and sensitive liquid chromatography tandem mass spectrometry method for simultaneous measurement of SDMA, ADMA and creatinine.MethodSerum samples were prepared by protein precipitation and dilution with acetonitrile prior to injection onto a Waters TQS-Micro. SDMA, ADMA, creatinine and their corresponding internal standard transitions were detected using multiple reaction monitoring after separation with a hydrophilic interaction liquid chromatography analytical column. Sample stability and intra-individual variation studies were also assessed following ethical approval.ResultsThe retention time for creatinine was 0.43, SDMA 1.10 and ADMA 1.14 min. Mean recovery for creatinine was 103%, SDMA was 100% and ADMA was 103%; matrix effects were minimal (<6%). Lower limit of quantitation for creatinine and SDMA/ADMA was 17.5 µmol/L and 0.1 µmol/L, respectively. Analytical imprecision showed a coefficient of variation <10% for all analytes across the working range of the assays. Intra-individual variation for creatinine was 4.7%, SDMA 7.5% and ADMA 7.6%.DiscussionWe have developed a rugged assay for measurement of SDMA, ADMA and creatinine by LC-MS/MS suitable for routine use. It is easy to perform owing to its simplicity and reproducibility. The stability of SDMA and ADMA pre- and post-centrifugation allows for their routine use without any special sample handling requirements.
BackgroundSymmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA) are naturally occurring amino acids classed as uraemic toxins by the European Uremic Toxins Work Group. SDMA is principally excreted through the kidneys and is a well-known renal function marker, and ADMA is a potent inhibitor of nitric oxide production. Here, we describe the development of a rapid and sensitive liquid chromatography tandem mass spectrometry method for simultaneous measurement of SDMA, ADMA and creatinine.MethodSerum samples were prepared by protein precipitation and dilution with acetonitrile prior to injection onto a Waters TQS-Micro. SDMA, ADMA, creatinine and their corresponding internal standard transitions were detected using multiple reaction monitoring after separation with a hydrophilic interaction liquid chromatography analytical column. Sample stability and intra-individual variation studies were also assessed following ethical approval.ResultsThe retention time for creatinine was 0.43, SDMA 1.10 and ADMA 1.14 min. Mean recovery for creatinine was 103%, SDMA was 100% and ADMA was 103%; matrix effects were minimal (<6%). Lower limit of quantitation for creatinine and SDMA/ADMA was 17.5 µmol/L and 0.1 µmol/L, respectively. Analytical imprecision showed a coefficient of variation <10% for all analytes across the working range of the assays. Intra-individual variation for creatinine was 4.7%, SDMA 7.5% and ADMA 7.6%.DiscussionWe have developed a rugged assay for measurement of SDMA, ADMA and creatinine by LC-MS/MS suitable for routine use. It is easy to perform owing to its simplicity and reproducibility. The stability of SDMA and ADMA pre- and post-centrifugation allows for their routine use without any special sample handling requirements.
Suggested guide to using lactate gap as a surrogate marker in the diagnosis of ethylene glycol overdose
Annals of Clinical Biochemistry, Ahead of Print.
BackgroundEthylene glycol (EG) poisoning, if not diagnosed rapidly, can lead to poor patient outcomes. Gas chromatography (GC) is primarily used for EG quantitation which is rarely available, and the turn-around time may be prolonged. Most lactate results from point-of-care (POCT) methods are falsely elevated in EG poisoning compared with automated chemistry analyser results. In combination, the lactate gap (POCT-Automated chemistry) can be used as surrogate marker in just about all laboratories to indicate likely EG toxicity and guide treatment.Case ReportA man presented by ambulance to hospital with severe agitation requiring mechanical ventilation to facilitate ongoing management. Venous blood gas analysis confirmed a high anion gap metabolic acidosis (HAGMA) with an elevated lactate. The lactate and osmolarity measured in the laboratory showed a normal lactate and high osmolarity, giving a large osmolar gap. The patient was immediately commenced on renal replacement therapy for presumed EG poisoning to minimize kidney injury, and the treatment continued for 19 hours. A very high EG concentration was confirmed by GC the next day.ConclusionAn elevated lactate gap along with a HAGMA and osmolar gap can provide rapid surrogate laboratory data indicating EG poisoning enabling timely treatment and better patient outcomes.
BackgroundEthylene glycol (EG) poisoning, if not diagnosed rapidly, can lead to poor patient outcomes. Gas chromatography (GC) is primarily used for EG quantitation which is rarely available, and the turn-around time may be prolonged. Most lactate results from point-of-care (POCT) methods are falsely elevated in EG poisoning compared with automated chemistry analyser results. In combination, the lactate gap (POCT-Automated chemistry) can be used as surrogate marker in just about all laboratories to indicate likely EG toxicity and guide treatment.Case ReportA man presented by ambulance to hospital with severe agitation requiring mechanical ventilation to facilitate ongoing management. Venous blood gas analysis confirmed a high anion gap metabolic acidosis (HAGMA) with an elevated lactate. The lactate and osmolarity measured in the laboratory showed a normal lactate and high osmolarity, giving a large osmolar gap. The patient was immediately commenced on renal replacement therapy for presumed EG poisoning to minimize kidney injury, and the treatment continued for 19 hours. A very high EG concentration was confirmed by GC the next day.ConclusionAn elevated lactate gap along with a HAGMA and osmolar gap can provide rapid surrogate laboratory data indicating EG poisoning enabling timely treatment and better patient outcomes.