Gitelman syndrome is an autosomal recessive renal tubular disorder caused by loss-of-function mutations in the SLC12A3 gene encoding the thiazide-sensitive sodium-chloride cotransporter (NCC) in the distal convoluted tubule. The defective NCC prevents sodium and chloride reabsorption, mimicking the pharmacological effect of chronic thiazide diuretic use. Compensatory mechanisms include activation of the renin-angiotensin-aldosterone system (causing hypokalemic metabolic alkalosis), increased calcium reabsorption (causing hypocalciuria -- a distinguishing feature from Bartter syndrome), and decreased magnesium reabsorption through poorly understood mechanisms (causing hypomagnesemia with muscle cramps, tetany, and cardiac arrhythmias). The nurse monitors serum electrolytes (potassium, magnesium, calcium), assesses for symptoms of hypokalemia (muscle weakness, fatigue, cardiac arrhythmias) and hypomagnesemia (tetany, tremor, QT prolongation), administers oral potassium and magnesium supplementation as prescribed, monitors ECG for dysrhythmias, encourages a high-sodium, high-potassium diet, and educates patients about lifelong supplementation needs and the generally favorable prognosis.