Exercise-induced acute renal failure associated with renal hypouricaemia: results of a questionnaire-based survey in Japan

Background. A retrospective investigation was conducted to define the clinical features of exercise-induced acute renal failure (ARF) associated with renal hypouricaemia with the aim of clarifying further the clinical features of the disease entity. Methods. A questionnaire was mailed to 43 institutions in Japan that had experienced case(s) of exercise-induced ARF associated with renal hypouricaemia. Fifty-four patients (48 males and six females) were identified from 38 institutions. Results. Median age at the first episode of ARF was 17 years (range 11-46). The maximal serum uric acid and creatinine levels were 4.40 +/- 2.49 (range 0.4-13.3) and 5.45 +/- 3.33 mg/dl (range 1.10-17.7), respectively. The serum uric acid level after recovery was 0.70 +/- 0.25 mg/dl (range 0.1-1.4). The short-term prognosis seemed to be good and histological findings in 28 patients showed minimal change or acute tubular necrosis except for one patient with chronic lesions. ART episodes occurred predominantly in September, October and May, mostly after strenuous exercise such as a short-distance race. The first symptoms were nausea/vomiting in 51 episodes, loin pain in 35, abdominal pain in 22, general fatigue in 16 and low-grade fever in seven. Thirteen patients (24.1%) experienced recurrent ARF at various intervals. Univariate and multivariate analyses failed to demonstrate any risk factor of ARF recurrence, although no female patients experienced ARF recurrence. Conclusions. The reason for the heterogeneity in ARF associated with renal hypouricaemia remains unknown. Further studies, especially on molecular mechanisms, are required to establish the best guidance against ARF recurrence.