Acute spontaneous tumor lysis presenting with hyperuricemic acute renal failure: clinical features and therapeutic approach

BACKGROUND: Acute spontaneous tumor lysis syndrome (STLS) presenting with hyperuricemic acute renal failure (ARF) is a rare disease which can be overlooked in patients with neoplasic disorders, requiring prompt recognition and aggressive management. This study examined the incidence, clinical characteristics and prognosis of this condition. METHODS: A retrospective study was performed, reviewing the records of all patients who developed ARF at Chang Gung Memorial Hospital between 1st July 1999 and 30th October 2002. Acute STLS was diagnosed based on pretreatment hyperuricemic ARF, ratio of urinary uric acid to creatinine (Cr) >1.0, and significantly elevated lactate dehydrogenase (LDH) (>500 units/L), together with a pathologically proven malignancy. Clinical course, metabolic parameters, response to therapeutics and outcome were assessed in all patients. RESULTS: STLS-induced acute uric acid nephropathy was identified in 10 out of 926 ARF patients (1.08%) studied. Most presentations were non-specific or related to malignancy symptoms. All patients had advanced tumors with large tumor burden, and abdominal organ involvement in 80% of patients. The 10 hyperuricemic patients became oliguric despite conservative therapy, and remained hyperuricemic (mean +/- SD: 20.7 +/- 5.0 mg/dL) until dialysis initiation. Seven patients (70%) developed diuresis, with an associated resolution of hyperuricemia, azotemia and metabolic derangements following dialysis initiation. The patients who developed diuresis had mean serum uric acid levels 9.3 +/- 3.1 mg/dL and median levels 9.8 mg/dL. Three patients (30%) survived, with two patients suffering residual renal function impairment. CONCLUSIONS: Acute STLS presenting with hyperuricemic ARF is a rare cause of acute uric acid nephropathy in patients with bulky or occult neoplastic disorders. The tumors that developed STLS had advanced stage or large tumor burden. Frequent abdominal organ involvement and non-specific initial presentations can obscure the nature of the disease and delay diagnosis. Unlike hyperuricemia and oliguria, which are constant findings, azotemia or impaired renal function is not always manifest on initial presentation. Poor outcomes in patients with STLS developing acute uric acid nephropathy make early recognition, aggressive management and prompt dialysis mandatory.