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Thyrotropin suppression by thyroid hormone replacement is correlated with thyroxine level normalization in central hypothyroidism.
Thyroid 2002; 12(9):823-7T

Abstract

We have retrospectively studied 41 patients with hypothalamic-pituitary disease and central hypothyroidism associated with hypopituitarism. Sixteen patients had nonsecreting pituitary macroadenoma, whereas different sellar and suprasellar pathologies affected all other patients. Pretreatment thyrotropin (TSH) level (mean +/- standard error of the mean [SEM]) was 2.04 +/- 0.25 mU/L (normal, 0.4-4), and gradually decreased to 0.51 +/- 0.19 mU/L (range, 0.009-3.38) by treatment with levothyroxine in a mean dose of 86 +/- 6 microg/d. TSH was suppressed by thyroid replacement to less than 0.5 mU/L in 80% of patients. Mean baseline free thyroxine (FT4) was 7.55 +/- 0.51 pmol/L (normal, 11.8-24.6) and gradually increased with thyroid hormone to 15.19 +/- 1.0 pmol/L, whereas total thyroxine (TT4) increased from 57.4 +/- 2.6 to 104.4 +/- 5.0 nmol/L (normal, 77-154). Mean pretreatment total triiodothyronine (TT3) was 1.44 +/- 0.09 nmol/L (normal, 1.1-2.7), and was not altered by treatment. Thyrotropin-releasing hormone (TRH) test was performed in 20 patients before thyroid replacement, and mean baseline and peak TSH levels were 1.33 +/- 0.3 and 7.14 +/- 1.62 mU/L, respectively. In 5 subjects TSH was stimulated to 6 mU/L or more, whereas in 5 others TSH was not affected. Based on linear regression of logarithm (Ln) TSH against FT4, a leftward shift of the TSH/FT4 ratio was demonstrated in patients with central hypothyroidism compared to 17 patients with primary hypothyroidism. Plotting measurements of TSH against FT4 for 6 individuals with central hypothyroidism showed different regression slope for each patient. Suppression of TSH by thyroid replacement to levels below 0.1 mU/L predicted euthyroidism in 92% of cases, compared to 34% when TSH was above 1 mU/L (p < 0.0001). In conclusion, in central hypothyroidism baseline TSH is usually within normal values, and is further suppressed by exogenous thyroid hormone as in primary hypothyroidism, but to lower levels. Thus, insufficient replacement may be reflected by inappropriately elevated TSH levels, and may lead to dosage increment.

Authors+Show Affiliations

Institute of Endocrinology, Sheba Medical Center, Tel-Hashomer, Israel. i_shimon@netvision.net.ilNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12481949

Citation

Shimon, Ilan, et al. "Thyrotropin Suppression By Thyroid Hormone Replacement Is Correlated With Thyroxine Level Normalization in Central Hypothyroidism." Thyroid : Official Journal of the American Thyroid Association, vol. 12, no. 9, 2002, pp. 823-7.
Shimon I, Cohen O, Lubetsky A, et al. Thyrotropin suppression by thyroid hormone replacement is correlated with thyroxine level normalization in central hypothyroidism. Thyroid. 2002;12(9):823-7.
Shimon, I., Cohen, O., Lubetsky, A., & Olchovsky, D. (2002). Thyrotropin suppression by thyroid hormone replacement is correlated with thyroxine level normalization in central hypothyroidism. Thyroid : Official Journal of the American Thyroid Association, 12(9), pp. 823-7.
Shimon I, et al. Thyrotropin Suppression By Thyroid Hormone Replacement Is Correlated With Thyroxine Level Normalization in Central Hypothyroidism. Thyroid. 2002;12(9):823-7. PubMed PMID: 12481949.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thyrotropin suppression by thyroid hormone replacement is correlated with thyroxine level normalization in central hypothyroidism. AU - Shimon,Ilan, AU - Cohen,Ohad, AU - Lubetsky,Aharon, AU - Olchovsky,David, PY - 2002/12/17/pubmed PY - 2003/4/9/medline PY - 2002/12/17/entrez SP - 823 EP - 7 JF - Thyroid : official journal of the American Thyroid Association JO - Thyroid VL - 12 IS - 9 N2 - We have retrospectively studied 41 patients with hypothalamic-pituitary disease and central hypothyroidism associated with hypopituitarism. Sixteen patients had nonsecreting pituitary macroadenoma, whereas different sellar and suprasellar pathologies affected all other patients. Pretreatment thyrotropin (TSH) level (mean +/- standard error of the mean [SEM]) was 2.04 +/- 0.25 mU/L (normal, 0.4-4), and gradually decreased to 0.51 +/- 0.19 mU/L (range, 0.009-3.38) by treatment with levothyroxine in a mean dose of 86 +/- 6 microg/d. TSH was suppressed by thyroid replacement to less than 0.5 mU/L in 80% of patients. Mean baseline free thyroxine (FT4) was 7.55 +/- 0.51 pmol/L (normal, 11.8-24.6) and gradually increased with thyroid hormone to 15.19 +/- 1.0 pmol/L, whereas total thyroxine (TT4) increased from 57.4 +/- 2.6 to 104.4 +/- 5.0 nmol/L (normal, 77-154). Mean pretreatment total triiodothyronine (TT3) was 1.44 +/- 0.09 nmol/L (normal, 1.1-2.7), and was not altered by treatment. Thyrotropin-releasing hormone (TRH) test was performed in 20 patients before thyroid replacement, and mean baseline and peak TSH levels were 1.33 +/- 0.3 and 7.14 +/- 1.62 mU/L, respectively. In 5 subjects TSH was stimulated to 6 mU/L or more, whereas in 5 others TSH was not affected. Based on linear regression of logarithm (Ln) TSH against FT4, a leftward shift of the TSH/FT4 ratio was demonstrated in patients with central hypothyroidism compared to 17 patients with primary hypothyroidism. Plotting measurements of TSH against FT4 for 6 individuals with central hypothyroidism showed different regression slope for each patient. Suppression of TSH by thyroid replacement to levels below 0.1 mU/L predicted euthyroidism in 92% of cases, compared to 34% when TSH was above 1 mU/L (p < 0.0001). In conclusion, in central hypothyroidism baseline TSH is usually within normal values, and is further suppressed by exogenous thyroid hormone as in primary hypothyroidism, but to lower levels. Thus, insufficient replacement may be reflected by inappropriately elevated TSH levels, and may lead to dosage increment. SN - 1050-7256 UR - https://www.unboundmedicine.com/medline/citation/12481949/Thyrotropin_suppression_by_thyroid_hormone_replacement_is_correlated_with_thyroxine_level_normalization_in_central_hypothyroidism_ L2 - https://www.liebertpub.com/doi/full/10.1089/105072502760339406?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -