Effect of Simultaneously Administered lopanoic Acid and Thyrotropin Releasing Hormone (TRH) on Thyroid Hormone Metabolism in Euthyroid Subjects

Summary

The cause of serum T₄ elevation after iopanoic acid administration was searched in euthyroid subjects. 3 gr iopanoic acid was given per os to 9 healthy volunteers (group I), in other 5 volunteers a TRH test was performed prior to iopanoic acid administration (group II). In group I TSH, T₄, FT₄I and rT₃ levels increased, in group II T₃ and FT₃I decreased, but no TSH, T₄, FT₄I increase was seen, obviously, because of the exhaustion of pituitary TSH content by TRH. On the ground of the findings T₄ elevation caused by iopanoic acid is predominantly consequence of TSH release and not that of inhibited T₄ conversion rate.

Key words

Iopanoic acid - TRH - T₄-T₃ conversion - T₄ metabolism