Oral purine loading for evaluation of uric acid excretion in patients with urinary calculi.

We present a model for oral uric acid loading which may be used to study the relapsing tendency of stone-formers. The oral administration of 2 g of guanosine was associated with two different response patterns of urinary uric acid excretion in patients with urolithiasis. The two groups also had considerably different relapse rates. The relapsing tendency in the group with the comparatively decreased reaction of urate excretion was less pronounced than in the group with enhanced uric acid excretion after oral purine loading.