Renal cysts and nephrocalcinosis in a patient with Bartter syndrome type III.

Chronic hypokalemia is known to induce renal cyst formation in some diseases including primary aldosteronism, distal renal tubular acidosis, Liddle disease and apparent mineralocorticoid excess syndrome. Although chronic hypokalemia is the main clinical feature of Bartter syndrome, renal cyst formation in this disease has never been reported. We describe a patient with classic Bartter syndrome who exhibited renal cysts and nephrocalcinosis. Direct sequencing analysis of the chloride channel CLC-Kb gene identified a heterozygous nonsense mutation (W610X) in exon 16 indicating a diagnosis of Bartter syndrome type III. Although the precise mechanism underlying the development of renal cysts in our patient remains unclear, chronic hypokalemia and nephrocalcinosis may contribute to cyst development.