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Hyperresponse to thyrotropin-releasing hormone accompanying small decreases in serum thyroid hormone concentrations.
J Clin Invest. 1974 Oct; 54(4):913-8.JCI

Abstract

To determine whether pituitary thyrotropin (TSH) responsiveness to thyrotropin-releasing hormone (TRH) is enhanced by small decreases in serum thyroxine (T4) and triiodothyronine (T3), 12 euthyroid volunteers were given 190 mg iodide po daily for 10 days to inhibit T4 and T3 release from the thyroid. Basal serum T4, T3, and TSH concentrations and the serum T4 and TSH responses to 400 mug TRH i.v. were assessed before and at the end of iodide administration. Iodide induced small but highly significant decreases in basal serum T4 (8.0+/-1.6 vs. 6.6+/-1.7 mug/100 ml; mean +/- SD) and T3 (128+/-15 vs. 110+/-22 ng/100 ml) and increases in basal serum TSH (1.3+/-0.9 vs. 2.1+/-1.0 muU/ml). During iodide administration, the TSH response to TRH was significantly increased at each of seven time points up to 120 min. The maximum increment in serum TSH after TRH increased from a control mean of 8.8+/-4.1 to a mean of 13.0+/-2.8 muU/ml during iodide administration. As evidence of the inhibitory effect of iodide on hormonal release, the increment in serum T3 at 120 min after TRH was significantly lessened during iodide administration (61+/-42 vs. 33+/-24 ng/100 ml). These findings demonstrate that small acute decreases in serum T4 and T3 concentrations, resulting in values well within the normal range, are associated both with slight increases in basal TSH concentrations and pronounced increases in the TSH response to TRH. These results demonstrate that a marked sensitivity of TSH secretion and responsiveness to TRH is applicable to decreasing, as well as increasing, concentrations of thyroid hormones.

Authors

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Pub Type(s)

Journal Article

Language

eng

PubMed ID

4214837

Citation

Vagenakis, A G., et al. "Hyperresponse to Thyrotropin-releasing Hormone Accompanying Small Decreases in Serum Thyroid Hormone Concentrations." The Journal of Clinical Investigation, vol. 54, no. 4, 1974, pp. 913-8.
Vagenakis AG, Rapoport B, Azizi F, et al. Hyperresponse to thyrotropin-releasing hormone accompanying small decreases in serum thyroid hormone concentrations. J Clin Invest. 1974;54(4):913-8.
Vagenakis, A. G., Rapoport, B., Azizi, F., Portnay, G. I., Braverman, L. E., & Ingbar, S. H. (1974). Hyperresponse to thyrotropin-releasing hormone accompanying small decreases in serum thyroid hormone concentrations. The Journal of Clinical Investigation, 54(4), 913-8.
Vagenakis AG, et al. Hyperresponse to Thyrotropin-releasing Hormone Accompanying Small Decreases in Serum Thyroid Hormone Concentrations. J Clin Invest. 1974;54(4):913-8. PubMed PMID: 4214837.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hyperresponse to thyrotropin-releasing hormone accompanying small decreases in serum thyroid hormone concentrations. AU - Vagenakis,A G, AU - Rapoport,B, AU - Azizi,F, AU - Portnay,G I, AU - Braverman,L E, AU - Ingbar,S H, PY - 1974/10/1/pubmed PY - 1974/10/1/medline PY - 1974/10/1/entrez SP - 913 EP - 8 JF - The Journal of clinical investigation JO - J Clin Invest VL - 54 IS - 4 N2 - To determine whether pituitary thyrotropin (TSH) responsiveness to thyrotropin-releasing hormone (TRH) is enhanced by small decreases in serum thyroxine (T4) and triiodothyronine (T3), 12 euthyroid volunteers were given 190 mg iodide po daily for 10 days to inhibit T4 and T3 release from the thyroid. Basal serum T4, T3, and TSH concentrations and the serum T4 and TSH responses to 400 mug TRH i.v. were assessed before and at the end of iodide administration. Iodide induced small but highly significant decreases in basal serum T4 (8.0+/-1.6 vs. 6.6+/-1.7 mug/100 ml; mean +/- SD) and T3 (128+/-15 vs. 110+/-22 ng/100 ml) and increases in basal serum TSH (1.3+/-0.9 vs. 2.1+/-1.0 muU/ml). During iodide administration, the TSH response to TRH was significantly increased at each of seven time points up to 120 min. The maximum increment in serum TSH after TRH increased from a control mean of 8.8+/-4.1 to a mean of 13.0+/-2.8 muU/ml during iodide administration. As evidence of the inhibitory effect of iodide on hormonal release, the increment in serum T3 at 120 min after TRH was significantly lessened during iodide administration (61+/-42 vs. 33+/-24 ng/100 ml). These findings demonstrate that small acute decreases in serum T4 and T3 concentrations, resulting in values well within the normal range, are associated both with slight increases in basal TSH concentrations and pronounced increases in the TSH response to TRH. These results demonstrate that a marked sensitivity of TSH secretion and responsiveness to TRH is applicable to decreasing, as well as increasing, concentrations of thyroid hormones. SN - 0021-9738 UR - https://www.unboundmedicine.com/medline/citation/4214837/Hyperresponse_to_thyrotropin_releasing_hormone_accompanying_small_decreases_in_serum_thyroid_hormone_concentrations_ L2 - https://doi.org/10.1172/JCI107831 DB - PRIME DP - Unbound Medicine ER -