Hyperuricemia and acute kidney injury secondary to spontaneous tumor lysis

42 Background: This is a rare instance of acute kidney injury caused by hyperuricemia due to 43 spontaneous tumor lysis syndrome and also the first case of spontaneous tumor lysis syndrome 44 reported in association with myelodysplastic syndrome. Case Presentation: A 53-year-old man 45 presented with abrupt oliguria. Laboratory findings on admission included hyperuricemia, 46 hyperphosphatemia, hypocalcemia, metabolic acidosis and rapidly rising serum creatinine, which 47 were consistent with acute tumor lysis syndrome in the absence of precipitating chemotherapy or 48 radiotherapy. After hemodialysis and oral uric acid lowering therapy, serum uric acid levels 49 returned to normal range and renal function rapidly recovered. The patient was diagnosed as 50 myelodysplastic syndrome eleven months later. Conclusion: Occult malignancy including solid 51 tumors and hematological malignancies should be carefully evaluated in the case of unexplainable 52 acute kidney injury with hyperuricemia. Aggressive investigations should be thoroughly 53 considered and repeated in this population. 54 55