Allopurinol is used to reduce urate formation in conditions where urate deposition has already occurred or is predictable. The specific diseases and conditions where it is used include gouty arthritis, skin tophi, kidney stones, idiopathic gout; uric acid lithiasis; acute uric acid nephropathy, neoplastic disease and myeloproliferative disease with high cell turnover rates, in which high urate levels occur either spontaneously, or after cytotoxic therapy, certain enzyme disorders which lead to overproduction of urate