Thyroid-Pituitary Feedback During Iodine Repletion
- 1 September 1976
- journal article
- research article
- Published by The Endocrine Society in Journal of Clinical Endocrinology & Metabolism
- Vol. 43 (3) , 601-605
- https://doi.org/10.1210/jcem-43-3-601
Abstract
The changes in serum triiodothyronine (T3), thyroxine (T4), and thyrotropin (TSH) were measured during iodine repletion in a woman who was severely iodine-deficient because of a congenital iodide-trapping defect. Serum T3 became detectable 12 h after iodine was begun and reached 68 ng/dl, a level within the normal range, by 36 h. It rose progressively during the first 9 days reaching a supranormal level (200 ng/dl) and then fell slowly to 130 ng/dl. Serum T4 was not detected (3 (P < 0.01). From the 10th through the 32nd day serum TSH fell more slowly (disappearance rate was 0.05/day) and correlation was with serum T4 (P < 0.001), not T3. It appears that either T3 or T4 may regulate TSH secretion by direct effects on the thyrotroph, although their intracellular mode of action has not been defined.Keywords
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