THYROID-HORMONES IN SERUM - EFFECTS OF X-RAY CONTRAST-MEDIA

Serial changes in circulating thyroid hormones following the use of iodine containing x-ray contrast media have been monitored in 31 euthyroid subjects, 11 of whom were goitrous. All subjects remained clinically euthyroid for the duration of the study. Significant changes in serum concentrations of thyroid hormones were apparent. There was a striking early (3 day) rise in serum reverse triiodothyronine paralleled by a fall in triiodothyronine and a later (21 day) rise in serum triiodothyronine. In goitrous subjects, serum thyroxine was also significantly higher than basal at 21 days. Individual values outside the normal range were frequently found. The pattern of change is best explained by an iodine induced alteration in thyroxine monodeiodination by peripheral tissues. Thyroid function tests should be interpreted with caution in patients who have received x-ray contrast media in the preceding month. © 1978 Springer-Verlag.