Disturbed metabolism of remnant lipoproteins in patients with subclinical hypothyroidism

Abstract

Subclinical hypothyroidism is defined by an elevated serum thyroid-stimulating hormone (TSH) level in the presence of normal free thyroid hormone levels (free thyroxine [T4] and free triiodothyronine [T3]). The prevalence of subclinical hypothyroidism ranges from 1% to 10% in the general population ( 1 Tunbridge W.M. Evered D.C. Hall R et al. The spectrum of thyroid disease in a community: the Whickham survey. Clin Endocrinol. 1977; 7: 481-493 Crossref PubMed Scopus (1877) Google Scholar , 2 Canaris G.J. Manowitz N.R. Mayor G. Ridgway E.C. The Colorado thyroid disease prevalence study. Arch Intern Med. 2000; 160: 526-534 Crossref PubMed Scopus (1906) Google Scholar , 3 Rivolta G. Cerutti R. Colombo R et al. Prevalence of subclinical hypothyroidism in a population living in the Milan metropolitan area. J Endocrinol Invest. 1999; 22: 693-697 PubMed Google Scholar ), and reaches 16% in elderly women ( 4 Sawin C.T. Chopra D. Azizi F et al. The aging thyroid Increased prevalence of elevated serum thyrotropin levels in the elderly. JAMA. 1979; 242: 247-250 Crossref PubMed Scopus (48) Google Scholar ). Some cross-sectional studies have demonstrated that total and low-density lipoprotein (LDL) cholesterol levels are higher in patients with subclinical hypothyroidism than in euthyroid controls ( 2 Canaris G.J. Manowitz N.R. Mayor G. Ridgway E.C. The Colorado thyroid disease prevalence study. Arch Intern Med. 2000; 160: 526-534 Crossref PubMed Scopus (1906) Google Scholar , 5 Staub J.J. Althaus B.U. Engler H et al. Spectrum of subclinical and overt hypothyroidism: effect on thyrotropin, prolactin, and thyroid reserve, and metabolic impact on peripheral target tissues. Am J Med. 1992; 92: 631-642 Abstract Full Text PDF PubMed Scopus (285) Google Scholar , 6 Kung A.W. Pang R.W. Janus E.D. Elevated serum lipoprotein (a) in subclinical hypothyroidism. Clin Endocrinol. 1995; 43: 445-449 Crossref PubMed Scopus (136) Google Scholar , 7 Bauer D.C. Ettinger B. Browner W.S. Thyroid functions and serum lipids in older women: a population-based study. Am J Med. 1998; 104: 546-551 Abstract Full Text Full Text PDF PubMed Scopus (82) Google Scholar ), and patients with subclinical hypothyroidism may have a greater risk of coronary heart disease ( 8 Bastenie P.A. Vanhaelst L. Bonnyns M et al. Preclinical hypothyroidism: a risk factor for coronary heart-disease. Lancet. 1971; 1: 203-204 Abstract PubMed Scopus (144) Google Scholar , 9 Dean J.W. Fowler P.B. Exaggerated responsiveness to thyrotropin releasing hormone: a risk factor in women with coronary artery disease. BMJ. 1985; 290: 1555-1561 Crossref PubMed Scopus (70) Google Scholar , 10 Hak A.E. Pols H.A. Visser T.J et al. Subclinical hypothyroidism is an independent risk factor for atherosclerosis and myocardial infarction in elderly women: the Rotterdam Study. Ann Intern Med. 2000; 132: 270-278 Crossref PubMed Scopus (1055) Google Scholar ).