Transient acute renal failure in the neonate.

We have observed a transient renal insufficiency in newborns associated with ultrasonographic finding of hyperechoic renal pyramids. This condition rapidly resolves, coinciding with both normalization of the renal ultrasound and the occurrence of significant proteinuria. Others have recognized a similar state of oliguria and cylindruria associated with a prolonged nephrogram on intravenous urography in newborns. There is evidence to suggest that hyaline cast deposition within the collecting tubules may account for these imaging abnormalities. The precise events surrounding the protein deposition are unknown, and it may be either the cause or the result from the transient renal dysfunction. Our 2 cases add to the evidence that there is a distinct entity of acute renal dysfunction, with identifying characteristics, in neonates associated with a good prognosis and rapid resolution.