Prophylaxis of uric acid and cystine stones.

Although they are two very distinct entities, uric acid and cystine stone disease share a common physico-chemical background, i.e. urinary supersaturation with respect to a compound that is poorly soluble in an acid milieu. Therefore, high-fluid intake and urine alkalinization, preferably by potassium citrate, are of utmost importance for prophylaxis. Urinary excretion of uric acid and cystine may be reduced by dietary measures as well as by drug therapy (allopurinol and thiols, respectively).