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For further information, see CMDT Part 22-26: Medullary Sponge Kidney

Key Features

  • 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

  • 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


  • CT shows

    • Cystic dilatation of the distal collecting tubules

    • A striated appearance in this area

    • Calcifications in the renal collecting system


  • 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

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