Potential for interference in immunoassays

 Summary: Biotin supplements can interfere significantly with immunoassay tests used in the clinical biochemistry laboratory and produce artefactually low or high results. If you have an unexpected result, please ask your patient if they are taking biotin.

 Immunoassays tests are biochemical tests commonly employed in the clinical biochemistry laboratory to measure the concentration of analytes. The basic mechanism of an immunoassay test is dependent on antibody and antigen interaction from which a signal is generated to indicate the concentration of the analyte of interest. Manufacturers of laboratory tests commonly use the Biotin-Streptavidin binding couple as an analyte extraction step in an immunoassay test’s design.

 Biotin containing supplements may interfere with the Biotin-Strepavidin binding couple and so in patients taking biotin supplements – (depending on assay design), biotin interference may cause artefactually high results (competitive assay), or artefactually low results (sandwich design).

 If you have a test result that does not fit the clinical picture, you may wish to exclude possible biotin interference as a cause by asking the patient/parent/carer about any over the counter supplements or checking for a biotin prescription. Patients may not know they are taking Biotin due to sometimes obscure product labelling. N.B. products marketed for hair, skin and nails often contain Biotin.

 In patients with normal diets and low dose multivitamin preparations, biotin should not be present at concentrations high enough to cause interference.

 5 to 10mg biotin supplements per tablet are available over the counter in many health stores and online.

 High-dose biotin (100mg) is sometimes used to treat metabolic diseases (isolated carboxylase defects and defects of biotin metabolism).

 Mega doses (up to 300mg/day) of biotin have also been used in clinical trials in the treatment of Multiple Sclerosis.

N.B. Biotin is renally excreted – it is therefore likely that in renal dysfunction, plasma biotin concentrations are higher than expected, and interference with immunoassay performance may occur at lower doses of biotin supplementation. 

N.B. Biotin is renally excreted – it is therefore likely that in renal dysfunction, plasma biotin concentrations are higher than expected, and interference with immunoassay performance may occur at lower doses of biotin supplementation

Manufacturers have been working to address biotin assay interference and have released new generations of assays to reduce biotin interference. The assays listed in table 3 state previously affected assays that are now Biotin resistant with the date the change came into effect.

Finally, erroneous results can occur unexpectedly with any specimen and there is no practical means of identifying specimens likely to cause problems in immunoassays.

Please contact the clinical biochemistry laboratory if there is any doubt about a result and/or potential interference.

Sources

Sturgeon C.M. and Viljoen A. (2011). Analytical error and interference in immunoassay: minimizing risk. Annals of Clinical Biochemistry, Volume 48, p418-432.

Grimsey P., Frey N., Bendig G., Zitzler J., Lorenz O., Kasapic D. and Zaugg C.E. (2017). Population pharmacokinetics of exogenous biotin and the relationship between biotin serum levels and in vitro immunoassay interference. International Journal of Pharmacokinetics, Volume 2 (4), p247-256.

Trambas C., Lu Z., Yen T. and Sikaris K. (2017). Characterization of the scope and magnitude of biotin interference in susceptible Roche Elecsys competitive and sandwich immunoassays. Annals of Clinical Biochemistry, Volume 55(2), p205-215.