[Xanthine lithiasis in a case of Lesch-Nyhan syndrome treated with allopurinol].

Classically it is considered that vital prognosis of Lesch-Nyhan syndrome depends on renal affectation secondary to uric nephropathy. A case of Lesch-Nyhan syndrome treated with Allopurinol is described which presented multiple and bilateral renal stones by precipitation of xanthine. Treatment with Allopurinol inhibits the formation of uric acid and qualitatively renal excretion of oxypurines modifies. In special circumstances (disminution of urinary output and pH), they can precipitate and originate a radiotransparent lithiasis with uric lithiasis. Interest of this case, lies in being alert to possible xanthine stone formation in patients with a large excretion of purinics metabolites, who are treated with Allopurinol.