Document Detail

Clinical and biochemical features of muscle dysfunction in subclinical hypothyroidism.
MedLine Citation:
PMID:  9329360     Owner:  NLM     Status:  MEDLINE    
Alterations in muscle structure and function have been reported in overt hypothyroidism, with decreased activity of enzymes involved in anaerobic and oxidative glucose metabolism. To test whether similar changes in muscle energy metabolism are present in subclinical hypothyroidism (sHT), we studied 12 patients with sHT who complained of mild neuromuscular symptoms. The control group included 10 sex- and age-matched healthy volunteers. Skeletal muscle lactate and pyruvate production were determined in the resting state and during dynamic arm exercise. During exercise, blood lactate was significantly higher in sHT patients than in controls from the third exercise step onward (P = 0.02 at 30%, p = 0.008 at 40%, and P = 0.002 at 50% of maximal voluntary contraction). Moreover, the mean increment in blood lactate during exercise was positively related (r2 = 0.44; P = 0.02) to the duration of sHT, but not to serum levels of TSH, free T3, or free T4. No significant difference was found in blood pyruvate concentrations between the two groups at baseline or during exercise. Thus, the lactate/pyruvate ratio curve paralleled the lactate curve in patients as well as controls. We conclude that muscle energy metabolism is impaired in sHT in rough proportion to the known duration of the disease. Early L-T4 therapy may be useful not only to provide specific treatment for such metabolic changes, but also to avoid progression to frank hypothyroidism.
F Monzani; N Caraccio; G Siciliano; L Manca; L Murri; E Ferrannini
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of clinical endocrinology and metabolism     Volume:  82     ISSN:  0021-972X     ISO Abbreviation:  J. Clin. Endocrinol. Metab.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-11-17     Completed Date:  1997-11-17     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0375362     Medline TA:  J Clin Endocrinol Metab     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3315-8     Citation Subset:  AIM; IM    
Department of Internal Medicine, University of Pisa, Italy.
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MeSH Terms
Energy Metabolism
Hypothyroidism / metabolism*,  physiopathology*
Lactates / blood
Muscles / metabolism*,  physiopathology*
Pyruvates / blood
Reference Values
Thyroid Hormones / blood
Reg. No./Substance:
0/Lactates; 0/Pyruvates; 0/Thyroid Hormones
Comment In:
J Clin Endocrinol Metab. 1998 May;83(5):1823   [PMID:  9589703 ]

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