Acute uric acid nephropathy in two gouty patients with moderate hyperuricemia and high urine acidity

Acute uric acid nephropathy has been described almost uniformly in patients with massive uric acid overload (malignancies with rapid cell destruction, epileptic seizures). Severe hyperuricosuria and intratubular uric acid precipitation result. Here we present two patients with gout, normal uric acid production, and moderate hyperuricemia, both of whom developed acute uric acid nephropathy. Because of pronounced urine acidity (pH values of 4.6 and 5.0 in morning fasting urines), supersaturation with respect to undissociated uric acid exceeded solubility (0.54 mmol/l), despite basal urate secretions of less than 2.2 mmol/24 hours. Additional predisposing factors, such as uricosuric treatment, heavy beer-drinking, over-consumption of purine-rich foods, and hot environment, were superimposed in both cases.