Thyroid dysfunction and their relation to cardiovascular risk factors such as lipid profile, hsCRP, and waist hip ratio in Korea.
BACKGROUND
Thyroid abnormalities affect a considerable portion of the population, and overt hypothyroidism is associated with an elevated risk of cardiovascular disease and adverse changes in blood lipids. Subclinical hypothyroidism is also associated with an increase risk of cardiovascular disease. So, we undertook this study to investigate the prevalence of overt and subclinical thyroid disorders and their associations with cardiovascular risk factors.


METHODS
This study involved 66,260 subjects (43,588 men, 22,672 women; between 20-80 years of age, mean age 41.5 +/- 9.6). Serum free thyroxine (FT4), thyroid stimulating hormone (TSH), total cholesterol, low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) were measured by RIA using commercial kits. High sensitivity C-reactive protein (hsCRP) levels were determined by nephelometry.


RESULTS
The prevalences of overt thyrotoxicosis, subclinical thyrotoxicosis, overt hypothyroidism and subclinical hypothyroidism were 5/1000 (334 subjects), 6.4/1000 (426 subjects), 1.6/1000 (108 subjects), and 6.4/1000 (375 subjects). Mean plasma total cholesterol and LDL-C were elevated in overt hypothyroidism than in normal controls (202.1 mg/dL and 121.8 mg/dL versus 197.1 mg/dL and 120.1 mg/dL, respectively) (p < 0.05). In subclinical hypothyroidism, mean total cholesterol and LDL-C levels were also elevated (201.9 mg/dL and 123.7 mg/dL) (p = 0.015, p = 0.047). Waist-to-hip ratio (WHR) was lower in overt thyrotoxicosis and higher in hypothyroidism.


CONCLUSIONS
The prevalence of thyroid dysfunction in Korea is not significantly different from that reported by other countries. It was also age dependent and higher in women, but this elevation in women was lower than expected. Patients with hypothyroidism exhibited higher waist-to-hip ratios, an index of obesity. Patients with subclinical hypothyroidism exhibited elevated atherogenic parameters (Total cholesterol, LDL-C). Therefore screening and treatment for subclinical hypothyroidism may be warranted due to its adverse effects on lipid metabolism.
Jung
Chan Hee
CH
Department of Internal Medicine, Kangbuk Samsung Hospital Sungkyunkwan University School of Medicine, Pyung-dong, Jongro-gu, Seoul.
Sung
Ki Chul
KC
Shin
Hun Sub
HS
Rhee
Eun Jung
EJ
Lee
Won Young
WY
Kim
Bum Soo
BS
Kang
Jin Ho
JH
Kim
Hyang
H
Kim
Sun Woo
SW
Lee
Man Ho
MH
Park
Jung Ro
JR
Kim
Seon Woo
SW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001824:Body Constitution; D002097:C-Reactive Protein / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000097:blood / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000453:epidemiology*; D007723:Korea / Q000453:epidemiology; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D011863:Radioimmunoassay; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
D008055:Lipids; D013972:Thyrotropin; D002097:C-Reactive Protein; D013974:Thyroxine