pseudohyponatremia

1) relic of days past when concentration of sodium was measured using flame photometry -> occurred because of non-aqueous volume occupied by lipid in hypertriglyceridemia & perhaps protein in monoclonal gammopathies & polyclonal gammopathies 2) ion-specific electrodes used in most modern instruments measure activity not concentration, thus making the issue of pseudohyponatremia obsolete But like old theories, old beliefs & practices don't die, their proponents do, & reference to pseudohyponatremia still appear in Internal Medicine Board review materials in 2006. Etiology: 1) hyperlipidemia 2) hyperproteinemia 3) hypercalcemia Laboratory: 1) serum sodium is low 2) serum triglycerides may be high 3) serum protein may be high 3) serum osmolality is normal Indications: - true hyponatremia (low serum osmolality)

References

Medical Knowledge Self Assessment Program (MKSAP) 14, American College of Physicians, Philadelphia 2006