<prompt> A 35-year-old man with AML and WBC of 100,000 cells ul is treated with chemotherapy and develops oliguric renal failure. His urine is acidic and numerous crystals are noted in the urine. The most likely diagnosisUrate nephropathyNephrocalcinosisLeukemic infiltration of the kidneysAcute tubular necrosis secondary to a nephrotoxic effect of his chemotherapy  <response>: The patient has urate nephropathy, characterized by the formation of urate crystals in the renal tubules and interstitium, which evoke an inflammatory reaction. This condition is most commonly observed during treatment for disseminated cancer e.g., leukemia, in which the release of purines from the dying cells leads to excessive synthesis of uric acid. An acid pH favors uric acid crystal formation. Allopurinol is normally given in these situations to prevent this serious complication.Nephrocalcinosis, which usually develops in cases of hypercalcemia andor hyperphosphatemia, would not be expected in the treatment of acute myelogenous leukemia. Leukemic infiltration of the kidneys may occur as a complication, but it does not produce crystals in the urine. Acute tubular necrosis secondary to a nephrotoxic effect of chemotherapy is always a possible complication, but it is associated with crystals in the urine. Acute pyelonephritis is not related to the treatment of leukemia. 