Korean J Intern Med.  2011 Dec;26(4):432-439. 10.3904/kjim.2011.26.4.432.

Serum TSH Level in Healthy Koreans and the Association of TSH with Serum Lipid Concentration and Metabolic Syndrome

Affiliations
  • 1Divison of Endocrinology and Metabolism, Department of Internal Medicine, CHA University College of Medicine, Seongnam, Korea. ywcho@cha.ac.kr
  • 2Department of Family Medicine, CHA University College of Medicine, Seongnam, Korea.

Abstract

BACKGROUND/AIMS
The proper treatment of subclinical hypothyroidism and the normal range of serum thyroid stimulating hormone (TSH) concentration are intensely debated. However, few reports have investigated TSH concentrations in Asian ethnic groups. Therefore, the present study was designed to define the TSH reference range in a Korean population and to investigate the metabolic significance of TSH concentration.
METHODS
We enrolled patients who underwent medical examination at the CHA Bundang Medical Center. Anthropometric data were evaluated, and serum TSH, free T4, and lipid profiles were assayed.
RESULTS
A total of 7,270 subjects were included. Mean TSH concentration of the study population was 1.82 +/- 0.95 mU/L, and we observed a sex-related difference in TSH concentration (male, 1.67 +/- 0.87 mU/L; female, 2.02 +/- 1.01 mU/L; p < 0.01). When the 2.5 and 97.5 percentiles were calculated, 95% TSH reference limits were 0.52-4.29 mU/L. TSH concentration was higher in elderly subjects, during winter, in postmenopausal women, and in obese males. Moreover, TSH showed significantly positive correlations with serum total cholesterol, triglyceride, and low density lipoprotein cholesterol regardless of sex, age, season, obesity, or menopausal status (all p < 0.01). Finally, TSH concentration was positively related to the prevalence of metabolic syndrome.
CONCLUSIONS
We demonstrated the association between TSH concentration within the normal reference range and serum lipid levels. TSH concentration varies according to sex, age, season, and body mass index (only in males). Moreover, high normal TSH levels were significantly associated with an increased prevalence of metabolic syndrome, which may be of importance when evaluating subjects with high normal TSH concentration.

Keyword

Thyroid function tests; Thyrotropin; Metabolic syndrome

MeSH Terms

Adult
Aged
Aged, 80 and over
Analysis of Variance
Body Mass Index
Cross-Sectional Studies
Ethnic Groups
Female
Humans
Korea/epidemiology
Lipids/*blood
Male
Menopause
Metabolic Syndrome X/*blood/epidemiology
Middle Aged
Risk Assessment
Thyroid Function Tests
Thyrotropin/*blood
Young Adult
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