[Distal tubular acidosis. Description of a classic case and of a type 4 case in neonatal single kidney].

During the last two years two babies with failure to thrive developed distal renal tubular acidosis (RTA). We report a female patient with classic RTA where the failure to thrive occurred from the 8th month of age associated with polyuria and polydipsia. A 45 day old infant had RTA type 4 associated with unilateral renal agenesis; type 4-RTA is characterized by inadequate urinary potassium excretion in the face of hyperkalemia, in distinct contrast to the other type of RTA in which enhanced kaliuria is observed. Treatment with oral bicarbonate resulted in sustained normalization of blood acid-base status and accelerated linear growth in both babies.