Ibrahim M. Faisal, Marwan M. Merkhan, Hani M. Almukhtar

Abstract

A xanthine-oxidoreductase enzyme is responsible for purine metabolism in our body; converting purine to its end product in the form of uric acid. Inhibition of this enzyme will then reduce uric acid in gout patients, however, it could have some side effects on other tissues and organs. The present study aims to identify the effect of long-term use of allopurinol in modulating the thyroid function in a patient with urate-type renal stone. The result revealed that allopurinol reduced the levels of free form of thyroid hormone and elevate TSH level with no effect reported with the bound thyroid hormones; these results were confirmed by ultrasonography results obtained for the patient before and after allopurinol therapy showing enlarged thyroid gland, change in echogenicity, and increased blood supply with nodule formation in few of them. These study has concluded that allopurinol could induce a state of subclinical hypothyroidism‎.