Disorders of water and sodium balance include: Fluid excess - plasma sodium may be high (due to sodium retention, e.g. Cushings), normal or low (water excess, e.g. in SIADH, psychogenic polydipsia) Fluid depletion - plasma sodium may be high (e.g. dehydration), normal or low (e.g. mineralocorticoid activity deficiency)
Pseudohyponatraemia - falsely low ISE results in patients with large amounts of protein in their serum (e.g. in multiple myeloma, hyperchylomicronaemia), this is due to a dilution error because of the reduced soluble fraction of the sample. Please contact the laboratory for more details.
