A 2 month old girl has failure to thrive, polyuria and medullary nephrocalcinosis affecting both kidneys. Investigations show blood pH 7.48, bicarbonate 25 mEq/l, potassium 2 mEq/l, sodium 126 mEq/l and chloride 88 mEq/l. The most likely diagnosis is -

Explanation

Clinical features of the infant --> Polyuria, Growth retardation, Medullary Nephrocalcinosis Electrolyte abnormalities: - Decreased potassium (Normal 3.5 — 5.0 meq/L)                 o Normal Bicarbonate (Normal 21-30 meq/L) Decreased sodium (Normal 136 — 145 ineq/L)                    o Increased pH (Normal 7.38 — 7.44 meq/L) Decreased Chloride (Normal 98 — 106 meq/L) C/F and electrolyte abnormalities in Bartter's syndrome a Hypokalemia                                o Polyurea and Nocturea (d/t hypokalemia) Metabolic alkalosis                    ❑ Increased urinary chloride (cause Hypochloremia) Normal to low blood pressure o Hypomagnesemia (seen in minority of patient) Growth retardation                    o Hypercalciurea (causes nephrocalcinosis which is visible on ultrasound) Other options Distal renal tubular acidosis      - It can be easily ruled out as it causes acidosis not alkalosis Primary hyperaldosteronism - In primary hyperaldosteronism, Sodium level is always increased and the B.F. is high. Pseudo hypoaldosteronism             - Aldosterone level is normal or increased but there are features of aldosterone deficiency such as decreased sodium and increased potassium.