Usual laboratory findings in patients with Gitelman syndrome.

Table 2: Usual laboratory findings in patients with Gitelman syndrome.

• Hypokalemia (serum K⁺ < 3.5 mmol/L) associated with inappropriate kaliuresis (potassium/creatinine in a random urine specimen > 18 mmol/mg)

• Hypomagnesemia (serum magnesium < 0.7 mmol/L) associated with renal magnesium wasting (fractional magnesium excretion > 4%)

• Hypocalciuria (calcium/creatinine in a random urine specimen < 0.07 mg/mg)

• Metabolic alkalosis

• Increased chloride excretion (fractional chloride excretion > 0.5%)

• Hyperreninemia

• Hypophosphatemia (occasionally)

• Genetic diagnosis: Inactivating mutations in the SLC12A3 gene encoding the thiazide sensitive Sodium-Chloride Cotransporter (NCC)