Acute kidney injury after acute gastroenteritis in an infant with hereditary hypouricemia

Hereditary hypouricemia is a rare disorder characterized by extremely low serum uric acid levels caused by excessive urinary excretion due to an inherited tubular defect in urate handling. Exercise-induced acute kidney injury (AKI) is the main complication of this disorder, though AKI may also be induced by other factors. A 7-month-old boy with hereditary hypouricemia developed AKI associated with severe dehydration caused by rotavirus gastroenteritis. He also showed severe hypernatremia and metabolic acidosis and received continuous renal replacement therapy for 3 days. He showed no signs of hydronephrosis or urolithiasis. However, hypouricemia was noted when his renal function recovered (serum uric acid < 0.6 mg/dl). Analysis of the urate transporter 1 gene revealed a homozygous nonsense mutation in exon 4 (c.774G > A, p.W258X). Both parents were heterozygous for the mutation and his younger brother was later determined to have severe hypouricemia (0.6 mg/dl). Conclusion: Uric acid is an essential factor for scavenging oxidative stressors. In this patient, severe dehydration may have directly caused pre-renal AKI, but susceptibility to oxidative stressors under severe dehydration, as well as exercise, may also contribute to AKI. Careful attention should be paid to dehydration, especially in young children, to avoid the development of AKI in patients with hereditary hypouricemia.