Unusual sodium and bicarbonate loss in an infant with obstructive urepathy

Abstract

The patient, a 50 days old boy, was admitted because severe hypenatronic dehydration and metabelio soidosis. Despite bilateral ureterostomy, chronic administration of high domes of sodium bioarboaate was required.

Functioaal evaluation was performed separatedly ia left/right kidney at 5 no. of age: Cin, 16.4/17.4 ml/min/1.73 m². Minimal urine pH, 6.6/6.7. E_HCO3 normal serum levels, 16. 9/15.7 %. Fractional distal sodium delivery, (${\text{C}}_{{\text{H}}_2\text{O}}$ + C_Na)/100 ml GFR 24.7/29.1 ml vs 19.8 ml in controls. Sodium transport at the diluting segment, (${\text{C}}_{{\text{H}}_2\text{O}}$/${\text{C}}_{{\text{H}}_2\text{O}}$ + C_Na) × 100, 60.6/56.5 vs 86.7 % in controls. Repeated studies at 17 no. of age showed no improvement in GFR and in proximal sodium aad bicarbonate rejection, but a moderate improvement in distal acidification and ia sodium reabsorption at the diluting segment.

This case demonstrates that functional abnormalities ia obstructive uropathy of infancy may attain both proximal and distal parts of the nephron, and also that recovery of tubular function aay not obligatorily follow desobstruotion.