Electrolytes affect most metabolic processes. They serve to maintain osmotic pressure and hydration of various body fluid compartments, proper body pH and regulation of appropriate heart and muscle functions. Electrolytes are also involved in oxidation-reduction reactions and participate as essential parts or, cofactors, in enzyme reactions. The sodium test system is intended for the quantitative measurement of sodium in serum, plasma and urine. Measurements obtained by this device are used in the diagnosis and treatment of aldosteronism (excessive secretion of the hormone aldosterone), diabetes insipidus (chronic excretion of large amounts of dilute urine, accompanied by extreme thirst), adrenal hypertension, Addison’s disease (caused by destruction of the adrenal glands), dehydration, inappropriate antidiuretic hormone secretion, or other diseases involving electrolyte imbalance.