Lack of evidence for pituitary thyrotroph down-regulation after 1 week of oral thyrotrophin-releasing hormone and metoclopramide under conditions of constant peripheral thyroid hormone levels

1995 ◽  
Vol 132 (3) ◽  
pp. 331-337 ◽  
Author(s):  
Stefan KG Grebe ◽  
John W Delahunt ◽  
Colin M Feek ◽  
Gordon Purdie ◽  
David J Porter
Keyword(s):  
Thyroid Hormone ◽  
Dopamine Antagonist ◽  
Minor Importance ◽  
Down Regulation ◽  
Double Blind ◽  
Thyrotrophin Releasing Hormone ◽  
Baseline Serum ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Thyroid Hormone Levels

Grebe SKG, Delahunt JW, Feek CM, Purdie G, Porter DJ. Lack of evidence for pituitary thyrotroph down-regulation after 1 week of oral thyrotrophin-releasing hormone and metoclopramide under conditions of constant peripheral thyroid hormone levels. Eur J Endocrinol 1995;132:331–7. ISSN 0804–4643 We investigated the pituitary thyrotrophin (TSH) response to repeated oral (non-pulsatile) thyrotrophin-releasing hormone (TRH) administration and potential modifying effects of dopamine antagonist treatment under conditions of constant peripheral thyroid hormone levels. In a randomized double-blind crossover trial, seven hypothyroid subjects, euthyroid on l-thyroxine, received 1 week each of oral TRH (40 mg, 12 hourly) plus metoclopramide (10 mg, 8 hourly) and TRH (40 mg, 12 hourly) plus placebo (one capsule, 8 hourly). At the beginning and end of each treatment period five samples of blood for estimation of serum TSH were taken over 1 h before ("baseline") and seven samples over 2 h after the treatment combination was given ("stimulated"). Serum free thyroxine, free triiodothyronine and prolactin levels also were measured. Mean log10 ± sem (log10 mIU/l) "baseline" serum levels TSH were −0.177 ± 0.183 (median 0.345 mIU/l (untransformed); range (r) 0.03–10.11 mIU/l; first quartile (lq) 0.22 mIU/l; third quartile (3q) 2.48 mIU/l) before and 0.182 ± 0.107 (median 1.385 mIU/l; r = 0.45–19.8 mIU/l; lq = 0.9 mIU/l; 3q = 1.78 mIU/l) after 1 week of treatment (p < 0.02). There were no significant differences between oral TRH plus metoclopramide and oral TRH plus placebo. Peripheral thyroid hormone levels and the "stimulated" TSH response (expressed as area under curve after TRH and metoclopramide or placebo; min · log10 mIU/l) remained unchanged after 1 week. In the absence of changes in peripheral thyroid hormone levels, oral TRH over 1 week may not result in down-regulation of anterior pituitary thyrotrophs. This suggests that pulsatility of TRH release be of minor importance only in the hypothalamic pituitary thyroid regulation of TSH release. Stefan KG Grebe, Department of Medicine, Wellington School of Medicine, Wellington, New Zealand

Thyrotrophin -releasing hormone in diagnosis

1974 ◽  
Vol 12 (8) ◽  
pp. 31-32
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Diagnostic Tests ◽  
Anterior Pituitary ◽  
Pituitary Stalk ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Thyroid Hormone Levels ◽  
Hypothalamic Function

Thyrotrophin-releasing hormone (TRH - Roche) is a synthetic tripeptide, L-pyroglutamyl-L-histidyl-L-proline-amide, which is identical with the porcine, ovine and human hypothalamic hormone that promotes the secretion of thyrotrophin. Secreted in the hypothalamus, it passes down the capillaries of the pituitary stalk to the anterior pituitary and there causes release of thyrotrophin. Thyroid hormones (triiodo-thyronine (T3) and thyroxine (T4)) interfere with the thyrotrophin (TSH)-releasing action of TRH, so that excess thyroid hormones block TSH release in response to TRH; conversely when thyroid hormone levels are low, increased secretion of TSH occurs. The hypothalamic secretion of TRH is probably directly influenced by the concentration of thyroid hormones in the blood reaching it. In addition TRH promotes the secretion of prolactin from the pituitary. TRH-Roche is marketed in Britain for use in hospitals in diagnostic tests of thyroid and of pituitary-hypothalamic function.

Changes in plasma thyrotrophin-releasing hormone, thyrotrophin, prolactin and thyroid hormone levels after intravenous, intranasal or rectal administration of synthetic thyrotrophin-releasing hormone in man

1984 ◽  
Vol 107 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Terunori Mitsuma ◽  
Tsuyoshi Nogimori
Keyword(s):  
Thyroid Hormone ◽  
Rectal Administration ◽  
Blood Stream ◽  
Rapid Decrease ◽  
Hormone Release ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Thyroid Hormone Levels

Abstract. Changes in plasma thyrotrophin-releasing hormone (TRH), thyrotrophin (TSH), prolactin and thyroid hormone levels after iv, intranasal, or rectal administration of synthetic TRH were studied in man. The plasma TRH concentration increased with all three routes, but remained at higher levels for a longer time after intranasal or rectal administration, in contrast to the rapid decrease after iv administration. Plasma TSH, prolactin and thyroid hormone levels increased significantly after intranasal or rectal administration and also remained elevated for a longer period than iv administration. These findings suggest that TRH administered intranasally or rectally enters the blood stream and stimulates TSH, prolactin and thyroid hormone release in man.

Evaluation of Positive Inotropic Drug Effects on Thyroid Hormone Levels after Open Heart Surgery

2015 ◽  
Vol 16 (2) ◽  
pp. 78
Author(s):  
Umit Kervan ◽  
Anil Ozen ◽  
Utku Unal ◽  
Irfan Tasoglu ◽  
Mahmut Mustafa Ulas ◽  
...  
Keyword(s):  
Drug Therapy ◽  
Thyroid Hormone ◽  
Heart Surgery ◽  
Open Heart Surgery ◽  
Open Heart ◽  
Inotropic Drug ◽  
Hormone Levels ◽  
Inotropic Drugs ◽  
Positive Inotropic Drug ◽  
Thyroid Hormone Levels

<p><b>Objective:</b> The aim of this study was to examine the effects of positive inotropic drugs, including adrenaline, dopamine, and dobutamine on thyroid hormone levels following open heart surgery.</p><p><b>Methods:</b> We analyzed free thyroid hormones (FT3 and FT4) and thyroid-stimulating hormones (TSH) in 200 consecutive patients undergoing open heart surgery. Patients were divided into 5 groups according to the inotropic drug administration as follows: Group A (n = 46) received dopamine alone; Group B (n = 40), dopamine and dobutamine; Group C (n = 36), dopamine, dobutamine, and adrenaline; Group D (n = 32), adrenaline alone; and Group E (n = 46), placebo. Procedural factors affecting thyroid hormones were recorded and included cardiopulmonary bypass (CPB) time, cross-clamping time, degree of hypothermia, and the duration and doses of positive inotropic drugs. Blood samples for hormone assays were collected before initiation of inotropic drug therapy (baseline) and postoperatively at 24, 72, and 120 hours after drug therapy.</p><p><b>Results:</b> FT3, FT4, and TSH levels at baseline were similar in all groups. Although there was a trend showing very slight increases in thyroid hormone levels from baseline to the 24th, 72nd, and 120th postoperative hours after drug therapy, these changes were not significant, and there were also no significant differences between the groups. There was also no significant statistical difference in CPB time, cross-clamping time, degree of hypothermia, and duration and doses of positive inotropic drugs between groups.</p><p><b>Conclusion:</b> Although thyroid hormone levels were affected by positive inotropic drug usage after open heart surgery, this effect was not significant and thyroid hormone levels remained within normal ranges.</p>

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