EFFECTS OF COMMONLY PRESCRIBED NONSTEROIDAL ANTIINFLAMMATORY DRUGS ONTHYROID-HORMONE MEASUREMENTS

PURPOSE: To assess the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on thyroid function tests. PATIENTS AND METHODS: Eighty-nine patients receiving NSAIDs and 22 control subjects not taking NSAIDs w ere studied in a cross-sectional survey at Veterans Affairs and Univer sity hospitals. Measurements of serum thyroxine (T4), free T4 index, t riiodothyronine (T3), and thyrotropin (thyroid-stimulating hormone [TS H]) were obtained for all subjects. RESULTS: Serum T4 measurements wer e lowered only in salsalate-treated patients, while serum T3 was depre ssed in patients receiving salsalate, diclofenac sodium, and naproxen. Serum T4 and T3 were unchanged in patients treated with diflunisal, i buprofen, indomethacin, piroxicam, or sulindac. Serum TSH was normal i n all subjects. CONCLUSIONS: Several NSAIDs can lower serum thyroid ho rmone concentrations, principally by interfering with the binding of T 4 and T3 to serum carrier proteins; patients taking these drugs remain euthyroid. Awareness of these interactions may prevent unnecessary di agnostic or therapeutic interventions.