Document Detail


Cardiovascular and metabolic responses to adrenaline infusion in patients with short-term hypothyroidism.
MedLine Citation:
PMID:  8736279     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: The relation between the clinical manifestations of thyroid disease (both hypo and hyper-thyroidism) and tissue sensitivity to catecholamines remains uncertain. It has been suggested that tissue adrenergic responsiveness is decreased in hypothyroidism, but the reports have been conflicting and have invariably focused on a single physiological response. Therefore the aim of the present study was to determine in patients with moderate, short-term, symptomatic hypothyroidism the responses of heart rate, systolic and diastolic blood pressure, forearm blood flow and metabolic rate to adrenaline infused at a rate known to achieve plasma concentrations in the middle of the physiological range. PATIENTS: Ten subjects (5M, age 43 +/- 3 years, mean +/- SEM) were studied. All were on thyroxine replacement for hypothyroidism following either thyroidectomy or radioactive iodine and had been biochemically euthyroid for at least 6 months. DESIGN: Studies were performed in random order. One study was undertaken on full replacement therapy and the other after 50 micrograms thyroxine daily for 2 weeks. After basal, supine measurements adrenaline was infused at 25 ng/kg/min for 30 minutes. MEASUREMENTS: Heart rate, blood pressure, blood glucose, metabolic rate and forearm blood flow were measured at rest and at 10-minute intervals throughout the adrenaline infusion. RESULTS: Free T4 (10.6 +/- 1.3 vs 17.6 +/- 2.0 pmol/l, P < 0.001) and free T3 (3.6 +/- 0.2 vs 4.6 +/- 0.3 pmol/l, P < 0.01) concentrations were significantly lower on 50 micrograms thyroxine than full replacement therapy. Fasting blood glucose concentrations (4.7 +/- 0.2 vs 4.7 +/- 0.1 mmol/l) were similar. The resting adrenaline concentrations were comparable, 0.29 +/- 0.18 and 0.24 +/- 0.14 nmol/l on 50 micrograms thyroxine and full replacement therapy respectively, and increased to a similar level (2.36 +/- 0.39 and 2.36 +/- 0.35 nmol/l) throughout the adrenaline infusion. The resting heart rate and metabolic rate were significantly lower on 50 micrograms thyroxine than full replacement therapy (68 +/- 2 vs 72 +/- 3 beats/min, P < 0.01; and 4.48 +/- 0.35 vs 4.88 +/- 0.39 kJ/min, P < 0.01) respectively, but the increase in heart rate (7 +/- 2 vs 8 +/- 2 beats/min) and metabolic rate (0.43 +/- 0.09 vs 0.43 +/- 0.06 kJ/min) did not differ on the two study days. Resting systolic blood pressure, diastolic blood pressure and forearm blood flow were comparable on 50 micrograms thyroxine and full replacement therapy as were the changes in systolic blood pressure (1 +/- 1 vs 1 +/- 1 mmHg), diastolic blood pressure (-7 +/- 2 vs -7 +/- 1 mmHg), forearm blood flow (1.4 +/- 0.1 vs 1.7 +/- 0.2 ml/min/100ml forearm) and blood glucose concentration (0.7 +/- 0.1 vs 0.7 +/- 0.1 mmol/l). CONCLUSIONS: Patients with short-term hypothyroidism appear to have a normal response to adrenaline infusion despite reduced baseline heart rate and metabolic rate. Thus, under physiological and mild pathophysiological conditions there appears to be no evidence of any synergy between thyroid status and sensitivity to catecholamines.
Authors:
A B Johnson; J Webber; P Mansell; I Gallen; S P Allison; I Macdonald
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical endocrinology     Volume:  43     ISSN:  0300-0664     ISO Abbreviation:  Clin. Endocrinol. (Oxf)     Publication Date:  1995 Dec 
Date Detail:
Created Date:  1996-10-15     Completed Date:  1996-10-15     Revised Date:  2009-09-29    
Medline Journal Info:
Nlm Unique ID:  0346653     Medline TA:  Clin Endocrinol (Oxf)     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  747-51     Citation Subset:  IM    
Affiliation:
Department of Medicine, University Hospital, Queens Medical Centre, Nottingham, UK.
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MeSH Terms
Descriptor/Qualifier:
Adult
Basal Metabolism / drug effects*
Blood Glucose / drug effects
Epinephrine / blood,  pharmacology*
Fatty Acids, Nonesterified / blood
Forearm / blood supply
Glycerol / blood
Hemodynamics / drug effects*
Humans
Hypothyroidism / blood,  physiopathology*
Middle Aged
Norepinephrine / blood
Pulmonary Gas Exchange / drug effects
Regional Blood Flow / drug effects
Thyroxine / blood
Triiodothyronine / blood
Grant Support
ID/Acronym/Agency:
//Wellcome Trust
Chemical
Reg. No./Substance:
0/Blood Glucose; 0/Fatty Acids, Nonesterified; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 56-81-5/Glycerol; 6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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