A 19-year-old woman evaluated for joint pain is found to have serum potassium 3.0 mEq/L, magnesium 1.2 mg/dL, and a normal anion gap metabolic acidosis. Blood pressure is 108/70 mmHg. Renin and aldosterone levels are elevated. Radiographs of the knees show linear calcification of the meniscal cartilage. Which diagnosis best explains all findings?

• A Gitelman syndrome ✓
• B Bartter syndrome
• C Primary hyperaldosteronism
• D Liddle syndrome

Explanation

Gitelman syndrome is an inherited defect of the thiazide-sensitive sodium chloride cotransporter in the distal convoluted tubule, producing hypokalaemic metabolic alkalosis, hypomagnesaemia, hypocalciuria, high renin and aldosterone, and normal or low blood pressure. Chronic hypomagnesaemia causes chondrocalcinosis, a distinguishing feature. Bartter syndrome mimics a loop diuretic effect with hypercalciuria and earlier presentation, and lacks prominent hypomagnesaemia. Primary aldosteronism and Liddle syndrome cause hypertension.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.