Peculiar round structures in the renal medulla in three patients with Bartter's syndrome

The renal histology and some clinical aspects of three patients with Bartter's syndrome are described. In all three cases, the renal function was moderately impaired and the concentrating ability was markedly reduced. Renal biopsy revealed hypertrophy, hyperplasia, and marked hypergranulation of the juxtaglomerular cells. In the medulla and/or medullary rays, nodular structures were observed which contained winding strands and vacuoles, surrounded by collagen fibers and fibroblasts. Some of them contained destroyed tubules with protein casts which leaked out into the interstitium. It is conceivable therefore that these structures were due to the reaction of the interstitium to leakage of the contents of the destroyed tubules. The destruction of the tubules, presumably due to severe and prolonged potassium depletion, might account for the impairment of the concentrating mechanism and might predict the later development of severe renal failure. Indomethacin combined with spironolactone did not raised the serum potassium in our cases.