Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 22-27: Medullary Sponge Kidney + Key Features Download Section PDF Listen +++ ++ A relatively common and benign disorder Present at birth and not usually diagnosed until the fourth or fifth decade Caused by autosomal dominant mutations in the MCKD1 or MCKD2 genes on chromosomes 1 and 16, respectively Kidneys have a marked irregular enlargement of the medullary and interpapillary collecting ducts + Clinical Findings Download Section PDF Listen +++ ++ May presents with gross or microscopic hematuria, recurrent urinary tract infections, or nephrolithiasis Common abnormalities are a decreased urinary concentrating ability and nephrocalcinosis Less common is incomplete type I distal renal tubular acidosis + Diagnosis Download Section PDF Listen +++ ++ CT shows Cystic dilatation of the distal collecting tubules with a striated appearance Calcifications in the renal collecting system + Treatment Download Section PDF Listen +++ ++ No known therapy Adequate fluid intake (2 L/day) helps prevent stone formation If hypercalciuria is present, thiazide diuretics are recommended because they decrease calcium excretion Alkali therapy is recommended if renal tubular acidosis is present