Potassium measurements are used to monitor electrolyte balance in the diagnosis and treatment of disease conditions characterised by low or high blood potassium levels.
Potassium is determined spectrophotometrically through a kinetic coupling assay system using potassium dependent pyruvate kinase. Pyruvate generated is converted to lactate accompanying conversion of NADH to NAD.
The corresponding decrease of optical density at 380 nm is proportional to the potassium concentration in the serum.