Xanthine-containing calculi during allopurinol therapy

Area of Science:

• Biochemistry
• Nephrology
• Genetics

Background:

• Lesch-Nyhan syndrome is a rare genetic disorder caused by hypoxanthine-guanine phosphoribosyltransferase deficiency, leading to severe hyperuricemia and neurological deficits.
• Urate overproduction is a key metabolic consequence requiring therapeutic intervention.

Observation:

• A patient with Lesch-Nyhan syndrome presented with urate crystalluria, which was initially managed with allopurinol.
• Despite successful control of urate crystalluria, the patient developed renal calculi.

Findings:

• Analysis of the renal calculi revealed a composition rich in various purines, notably xanthine, alongside oxypurinol and hypoxanthine.
• Allopurinol therapy, while effective for hyperuricemia, appeared to contribute to the accumulation of xanthine in renal stones.

Implications:

• This case underscores the potential risk of xanthine nephropathy during allopurinol treatment for conditions causing urate overproduction.
• Maintaining adequate hydration and high urine flow rate is crucial to mitigate the risk of purine stone formation in patients undergoing allopurinol therapy.
• Understanding purine metabolism and drug-induced stone formation is vital for managing patients with Lesch-Nyhan syndrome and other hyperuricemic states.