Urinary Excretion of Urate in Renal Calcium Stone Disease and in Renal Tubular Acidification Disturbances

Abstract

The 24 h urinary excretion of urate was investigated in 467 consecutive stone formers (350 males and 117 females) and 89 apparently healthy controls with no history of stone disease. Males had a higher urinary excretion of urate than females but there was no difference between stone formers and controls. Urinary urate decreased with advancing age. Patients with a proximal tubular acidification defect had a lower urate clearance than patients with a normal acidification of the urine. Patients with hyperuricosuria presented a higher frequency of stone operations but a lower stone episode rate than matched normouricosuric stone formers. Hyperuricosuria in combination with renal acidification defects was associated with the highest frequency of stone operations. Hyperuricosuric patients also had a higher excretion of calcium than normouricosuric patients. Hyperuricosuria is not a common feature of Ca stone disease but when present is associated with a more severe stone disease in terms of stone operations.