A 14-year-old boy presents with progressive muscle cramps and lightheadedness. Vital signs show BP 96/58 mmHg, HR 102/min, RR 18/min. Labs reveal hypokalemic metabolic alkalosis with elevated plasma renin (8.5 ng/mL/hr) and aldosterone (28 ng/dL). Urine calcium is markedly elevated at 450 mg/day. Serum creatinine is normal at 0.8 mg/dL. He denies vomiting or diarrhea. A defect in which of the following transporters is most likely responsible?
- A)Na bicarbonate cotransporter in the proximal tubule
- B)Aquaporin 2 channel in collecting duct cells
- C)Epithelial sodium channel in principal cells
- D)Na Cl cotransporter in the distal convoluted tubule
- E)Na K 2Cl cotransporter in the thick ascending limbGABARITO
Explicação
Bartter syndrome mimics chronic loop diuretic use because it involves loss of Na K 2Cl cotransporter activity in the thick ascending limb. This causes hypokalemic metabolic alkalosis, volume depletion with secondary hyperreninemia, and increased urinary calciu... Ver explicação completa e trilha adaptativa →