Subclinical Hypothyroidism and the Prevalence of the Metabolic Syndrome

Abstract

There is currently controversial data regarding the prevalence of MS among SCH patients. The aim of the study was to investigate the prevalence of MS in an adult population with SCH. A cross-sectional study was conducted among 6 998 adults in China. Epidemiological information and medical data were obtained (fasting plasma glucose, triglycerides, high density lipoprotein-C, and thyroid function). The IDF criteria were applied for the diagnosis of MS. SCH was defined as TSH more than 4.5 mIU/l with normal values for FT3 and FT4. Among the 6 560 participants, 21.5% were diagnosed with MS and 8.2% suffered from SCH. MS was found in 21.3% in the euthyroidism (EUT) group and in 25.7% in the SCH group (p<0.05). However, this difference between EUT and SCH in MS prevalence was not statistically significant after adjusting for age. Of note, the prevalence of MS increased with age. The proportions of systemic hypertension, hypertriglyceridemia, impaired fasting glucose, and low HDL-C were 86.7, 59.7, 45.1 and 65.9% in EUT while the corresponding values in SCH were 89.9, 63.8, 39.9 and 72.5%, respectively (the differences, however, did not reach statistical significance). The prevalence of high BP, high TG, elevated FBP, and low HDL-C as well as the percentage of patients fulfilling the IDF criteria for the metabolic syndrome are not significantly different among SCH and EUT after adjusting for age. Therefore, subclinical hypothyroidism appears not as an independent risk factor for the metabolic syndrome in this population.

Key words

thyroid - subclinical hypothyroidism - metabolic syndrome - TSH

References

• 1 Eckel RH, Alberti KG, Grundy SM, Zimmet PZ. The metabolic syndrome.  Lancet. 2010;  375 181-183
• 2 Miranda PJ, DeFronzo RA, Califf RM, Guyton JR. Metabolic syndrome: definition, pathophysiology, and mechanisms.  Am Heart J. 2005;  149 33-45
• 3 Garber AJ. The metabolic syndrome.  Med Clin North Am. 2004;  88 837-846, ix
• 4 Lewis JG, Borowski KK, Shand BI, George PM, Scott RS. Plasma sex hormone-binding globulin, corticosteroid-binding globulin, cortisol, and free cortisol levels in outpatients attending a lipid disorders clinic: a cross-sectional study of 1 137 subjects.  Horm Metab Res. 2010;  42 274-279
• 5 Wilson GR, Curry Jr RW. Subclinical thyroid disease.  Am Fam Physician. 2005;  72 1517-1524
• 6 Kvetny J, Wilms L, Pedersen PL, Larsen J. Subclinical hypothyroidism affects mitochondrial function.  Horm Metab Res. 2010;  42 324-327
• 7 Monzani F, Dardano A, Caraccio N. Does treating subclinical hypothyroidism improve markers of cardiovascular risk?.  Treat Endocrinol. 2006;  5 65-81
• 8 Walsh JP, Bremner AP, Bulsara MK, O’leary P, Leedman PJ, Feddema P, Michelangeli V. Subclinical thyroid dysfunction as a risk factor for cardiovascular disease.  Arch Intern Med. 2005;  165 2467-2472
• 9 Roos A, Bakker SJ, Links TP, Gans RO, Wolffenbuttel BH. Thyroid function is associated with components of the metabolic syndrome in euthyroid subjects.  J Clin Endocrinol Metab. 2007;  92 491-496
• 10 Teixeira PF, Reuters VS, Ferreira MM, Almeida CP, Reis FA, Melo BA, Buescu A, Costa AJ, Vaisman M. Treatment of subclinical hypothyroidism reduces atherogenic lipid levels in a placebo-controlled double-blind clinical trial.  Horm Metab Res. 2008;  40 50-55
• 11 Walsh JP, Bremner AP, Bulsara MK, O’leary P, Leedman PJ, Feddema P, Michelangeli V. Thyroid dysfunction and serum lipids: a community-based study.  Clin Endocrinol (Oxf). 2005;  63 670-675
• 12 Uzunlulu M, Yorulmaz E, Oguz A. Prevalence of subclinical hypothyroidism in patients with metabolic syndrome.  Endocr J. 2007;  54 71-76
• 13 Baloch Z, Carayon P, Conte-Devolx B, Demers LM, Feldt-Rasmussen U, Henry JF, LiVosli VA, Niccoli-Sire P, John R, Ruf J, Smyth PP, Spencer CA, Stockigt JR. Laboratory medicine practice guidelines. Laboratory support for the diagnosis and monitoring of thyroid disease.  Thyroid. 2003;  13 3-126
• 14 Ford ES, Giles WH, Dietz WH. Prevalence of the metabolic syndrome among US adults: findings from the third National Health and Nutrition Examination Survey.  JAMA. 2002;  287 356-359
• 15 Zhao Z, Nie H, He H, Yan Z, Liu D, Luo Z, Ma L, Ni Y, Chen J, Jing J, Cao T, Yang H, Tepel M, Zhang W, Zhu Z. High-sensitivity C-reactive protein predicts target organ damage in Chinese patients with metabolic syndrome.  Metabolism. 2007;  56 1612-1619
• 16 Hu XS, Guo ZR, Zhou H, Shi ZM, Wu M, Zhang J, Sun GX, Zhou ZY, Pan XQ, Yao CL. Study on the prevalence of metabolic syndrome among 35–74 year-olds in Jiangsu province.  Zhonghua Liu Xing Bing Xue Za Zhi. 2006;  27 751-756
• 17 Hollowell JG, Staehling NW, Flanders WD, Hannon WH, Gunter EW, Spencer CA, Braverman LE. Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III).  J Clin Endocrinol Metab. 2002;  87 489-499
• 18 Kvetny J, Heldgaard PE, Bladbjerg EM, Gram J. Subclinical hypothyroidism is associated with a low-grade inflammation, increased triglyceride levels and predicts cardiovascular disease in males below 50 years.  Clin Endocrinol (Oxf). 2004;  61 232-238
• 19 Brabant G, Beck-Peccoz P, Jarzab B, Laurberg P, Orgiazzi J, Szabolcs I, Weetman AP, Wiersinga WM. Is there a need to redefine the upper normal limit of TSH?.  Eur J Endocrinol. 2006;  154 633-637
• 20 Waise A, Price HC. The upper limit of the reference range for thyroid-stimulating hormone should not be confused with a cut-off to define subclinical hypothyroidism.  Ann Clin Biochem. 2009;  46 93-98
• 21 Wartofsky L, Dickey RA. The evidence for a narrower thyrotropin reference range is compelling.  J Clin Endocrinol Metab. 2005;  90 5483-5488
• 22 Ruhla S, Weickert MO, Arafat AM, Osterhoff M, Isken F, Spranger J, Schofl C, Pfeiffer AF, Mohlig M. A high normal TSH is associated with the metabolic syndrome.  Clin Endocrinol (Oxf). 2010;  72 696-701
• 23 Garduno-Garcia JJ, virde-Garcia U, Lopez-Carrasco G, Padilla Mendoza ME, Mehta R, Rellano-Campos O, Choza R, Sauque L, Garay-Sevilla ME, Malacara JM, Gomez-Perez FJ, Guilar-Salinas CA. TSH and free thyroxine concentrations are associated with differing metabolic markers in euthyroid subjects.  Eur J Endocrinol. 2010;  163 273-278
• 24 Liu D, Jiang F, Shan Z, Wang B, Wang J, Lai Y, Chen Y, Li M, Liu H, Li C, Xue H, Li N, Yu J, Shi L, Bai X, Hou X, Zhu L, Lu L, Wang S, Xing Q, Teng W. A cross-sectional survey of relationship between serum TSH level and blood pressure.  J Hum Hypertens. 2010;  24 134-138

Correspondence