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The pituitary-thyroid axis in acromegaly.
Horm Metab Res. 1988 Dec; 20(12):755-7.HM

Abstract

The pituitary-thyroid axis of 12 acromegalic patients was evaluated by measurement of the serum concentrations (total and free) of thyroxine (T4), triiodothyronine (T3) and reverse T3 (rT3) and thyrotropin (TSH), growth hormone (GH) and prolactin (PRL) before and after iv stimulation with thyrotropin releasing hormone (TRH). Using an ultrasensitive method of TSH measurement (IRMA) basal serum TSH levels of the patients (0.76, 0.07-1.90 mIU/l) were found slightly, but significantly (P less than 0.01), lower than in 40 healthy controls (1.40, 0.41-2.50 mIU/l). The total T4 levels (TT4) were also reduced (84, 69-106 nmol/l vs 100, 72-156 nmol/l, P less than 0.01) and significantly correlated (P less than 0.02, R = 0.69) to the TSH response to TRH, suggesting a slight central hypothyroidism. The acromegalics had, however, normal serum levels of TT3 (1.79, 1.23-2.52 nmol/l vs 1.74, 0.78-2.84 nmol/l, P greater than 0.10), but significantly decreased levels of TrT3 (0.173, 0.077-0.430 nmol/l vs 0.368, 0.154-0.584 nmol/l, P less than 0.01) compared to the controls. The serum concentration of the free iodothyronines (FT4, FT3, FrT3) showed similar differences between acromegalics and normal controls. All the acromegalics showed a rise of serum TSH, GH and PRL after TRH. Positive correlation (P less than 0.05, R = 0.59) was found between the TSH and GH responses, but not between these two parameters and the PRL response to TRH. These findings may be explained by the existence of a central suppression of the TSH and GH secretion in acromegalic subjects, possibly exerted by somatostatin. Euthyroidism might be maintained by an increased extrathyroidal conversion of T4 to T3.

Authors+Show Affiliations

Medical Endocrinological Department F, Fredericksborg County Hospital, Hillerød, Denmark.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

3146541

Citation

Eskildsen, P C., et al. "The Pituitary-thyroid Axis in Acromegaly." Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme, vol. 20, no. 12, 1988, pp. 755-7.
Eskildsen PC, Kruse A, Kirkegaard C. The pituitary-thyroid axis in acromegaly. Horm Metab Res. 1988;20(12):755-7.
Eskildsen, P. C., Kruse, A., & Kirkegaard, C. (1988). The pituitary-thyroid axis in acromegaly. Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme, 20(12), 755-7.
Eskildsen PC, Kruse A, Kirkegaard C. The Pituitary-thyroid Axis in Acromegaly. Horm Metab Res. 1988;20(12):755-7. PubMed PMID: 3146541.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The pituitary-thyroid axis in acromegaly. AU - Eskildsen,P C, AU - Kruse,A, AU - Kirkegaard,C, PY - 1988/12/1/pubmed PY - 1988/12/1/medline PY - 1988/12/1/entrez SP - 755 EP - 7 JF - Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme JO - Horm. Metab. Res. VL - 20 IS - 12 N2 - The pituitary-thyroid axis of 12 acromegalic patients was evaluated by measurement of the serum concentrations (total and free) of thyroxine (T4), triiodothyronine (T3) and reverse T3 (rT3) and thyrotropin (TSH), growth hormone (GH) and prolactin (PRL) before and after iv stimulation with thyrotropin releasing hormone (TRH). Using an ultrasensitive method of TSH measurement (IRMA) basal serum TSH levels of the patients (0.76, 0.07-1.90 mIU/l) were found slightly, but significantly (P less than 0.01), lower than in 40 healthy controls (1.40, 0.41-2.50 mIU/l). The total T4 levels (TT4) were also reduced (84, 69-106 nmol/l vs 100, 72-156 nmol/l, P less than 0.01) and significantly correlated (P less than 0.02, R = 0.69) to the TSH response to TRH, suggesting a slight central hypothyroidism. The acromegalics had, however, normal serum levels of TT3 (1.79, 1.23-2.52 nmol/l vs 1.74, 0.78-2.84 nmol/l, P greater than 0.10), but significantly decreased levels of TrT3 (0.173, 0.077-0.430 nmol/l vs 0.368, 0.154-0.584 nmol/l, P less than 0.01) compared to the controls. The serum concentration of the free iodothyronines (FT4, FT3, FrT3) showed similar differences between acromegalics and normal controls. All the acromegalics showed a rise of serum TSH, GH and PRL after TRH. Positive correlation (P less than 0.05, R = 0.59) was found between the TSH and GH responses, but not between these two parameters and the PRL response to TRH. These findings may be explained by the existence of a central suppression of the TSH and GH secretion in acromegalic subjects, possibly exerted by somatostatin. Euthyroidism might be maintained by an increased extrathyroidal conversion of T4 to T3. SN - 0018-5043 UR - https://www.unboundmedicine.com/medline/citation/3146541/The_pituitary_thyroid_axis_in_acromegaly_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2007-1010940 DB - PRIME DP - Unbound Medicine ER -