PROSPECTIVE STUDIES OF THYROID-FUNCTION IN PATIENTS RECEIVING GOLD THERAPY

Gold inhibits the Type I deiodinase that provides the bulk of circulat ing T-3 in humans. We prospectively studied thyroid function in patien ts receiving increasing parenteral cumulative gold doses. Eight consec utive euthyroid patients with rheumatoid or psoriatic arthritis who we re initiating intramuscular gold therapy were enrolled. Serum thyroid hormone levels (total T-4, T-3, and rT(3)) and TSH were measured for e ach subject at various intervals during gold therapy. For analysis, th e free T-4 and free T-3 indices, TSH concentrations, and T-4/T-3 ratio s were correlated with cumulative gold dose. Neither individual nor po oled linear regressions showed a significant correlation between cumul ative gold dose and any of the thyroid function parameters. Thyroid fu nction is not affected in patients receiving up to 1500 mg of gold com pounds. The most likely explanation for this is that gold principally accumulates in the Kupffer cells and renal cortex and these cells do n ot express Type I deiodinase.