Successful treatment of short stature and delayed puberty in congenital magnesium-losing kidney.

Bartter's syndrome is a well described but uncommon disease characterized by hypokalaemia and hyperplasia of the juxtaglomerular apparatus of the kidney. It may present in infancy with failure to thrive and muscle weakness; it commonly causes short stature. Lesions at different sites within the renal tubule have been proposed as the cause of the syndrome. However, the biochemical abnormalities in many cases can be explained by defective reabsorption of chloride in the ascending loop of Henle, with loss of sodium and water and a secondary increase in renin and aldosterone concentrations. Less severe cases have been described which present in adolescence and have tetany as a prominent feature. Primary renal loss of magnesium associated with potassium wasting has been described in such cases and it has been suggested that these can be distinguished from classical Bartter's syndrome by hypocalciuria. This less well characterized disease has been named Welt, Gitelman-Welt or Gitelman syndrome and may include deficient tubular reabsorption of chloride, but the sites of magnesium and potassium loss in the kidney are uncertain. We describe a patient with this syndrome who presented with short stature, delayed puberty and tetany and responded well to magnesium replacement.