USE OF CALCIUM EXCRETION VALUES TO DISTINGUISH 2 FORMS OF PRIMARY RENAL TUBULAR HYPOKALEMIC ALKALOSIS - BARTTER AND GITELMAN SYNDROMES

Clinical or biochemical findings were reevaluated in 34 pediatric patients with primary renal tubular hypokalemic metabolic alkalosis. The patients were sub-divided into two groups. Bartter syndrome (primary renal tubular hypokalemic metabolic alkalosis with normocalciuria or hypercalciuria) was diagnosed in 18 patients with molar urinary calcium/creatinine ratios > 0.20, and Gitelman syndrome (primary renal tubular hypokalemic metabolic alkalosis with magnesium deficiency and hypocalciuria) was diagnosed in 16 patients with molar urinary calcium/creatinine ratios less-than-or-equal-to 0.20 and plasma magnesium levels < 0.75 mmol/L. Some clinically important differences between the groups were observed. Patients with Bartter syndrome were often born after pregnancies complicated by polyhydramnios (8/18) or premature delivery (7/18) and had short stature (11/18) or polyuria, polydipsia, and a tendency to dehydration (16/18) during infancy (12/18) or before school age (18/18). Patients with Gitelman syndrome had tetanic episodes (12/16) or short stature (3/16) at school age (14/16). We conclude that the Bartter and Gitelman syndromes represent two distinct variants of primary renal tubular hypokalemic metabolic alkalosis and are easily distinguished on the basis of urinary calcium levels.