Bartter syndrome is characterized by which combination?

• A. Normal blood pressure, low potassium, metabolic alkalosis, elevated renin and aldosterone
• B. Hypertension, high potassium, metabolic acidosis
• C. Normal BP, hyperkalemia, metabolic acidosis
• D. Hypotension, hyperkalemia, metabolic alkalosis

Answer: (A)

Bartter syndrome is a salt-wasting tubulopathy that mimics chronic loop diuretic use. The defect in the thick ascending limb Na-K-2Cl transporter causes more sodium delivery to the distal nephron, so sodium is reabsorbed in the collecting duct in exchange for potassium and hydrogen ions. That leads to potassium loss (hypokalemia) and hydrogen ion loss (metabolic alkalosis), along with volume depletion. The body responds by activating the renin-angiotensin-aldosterone system, raising renin and aldosterone levels. Because the underlying problem is salt wasting rather than volume overload, blood pressure remains normal (often on the lower side). This combination—normal blood pressure with low potassium, metabolic alkalosis, and elevated renin and aldosterone—fits Bartter syndrome best.