A Frequency of Hypothyroidism in a Population of Hypercholesterolemin Subjects / 대한내분비학회지

ABSTRACT

BACKGROUND: Hypothyroidism is a treatable cause of secondary hyperlipidemia. The lipid profile usually seen is an increased total and low density lipoprotein(LDL) cholesterol, and the plasma triglyceride may also be increased. Hypercholesterolemia associated with hypothyroidism is an important factor in the pathogenesis of coronary artery disease(CAD). And the hyperchole-sterolemia caused by hypothyroidism is potentially reversible by thyroid hormone replacement therapy. Hypothyroidism should be ruled out by routine laboratory screening as a treatable cause of secondary hyperlipidemia and increased CAD risk. We carried out this study aimed at evaluating the frequency of hypothyroidism and its relationship with serum cholesterol concentration in Koreans. METHODS: We investigated 15028(men 8273, women 6755) Korean subjects who visited our hospital center for health promotion during an one year period(from January 1, 1996, to December 31, 1996). Among them, we analyzed 6756 hypercholesterolemic subjects whose serum cholesterol levels were greater than 200 mg/dL. They performed thyroid function tests(total T, T4, and TSH) and lipid profiles(total cholesterol, triglyceride and HDL-cholesterol) were measured by enzyme assay. We defined hypothyroidism by serum thyrotropin values greater than 5 U/mL. RESULTS: The observed prevalence of hypothyroidism was 2.4%(163/6756). Among those with high TSH levels, 17(10.4%) had overt hypothyroidism with a low T4 (below 6 g/dL) level. As we analyzed the frequency of hypothyroidism according to cholesterol range by 20 mg/dL, the frequency was significantly increased in the group whose serum cholesterol levels were greater than 300 mg/dL, especially in women over 50 years of age. Analysis of lipid parameters showed that hypertriglyceridemia was frequent and hyperHDLaemia was observed in hypothyroidic populations. CONCLUSION: Screening for hypothyroidism by measurement of thyrotropin values is of particular importance in patients with hypercholesterolemia. And the frequency of hypothyroidism was more significantly increased in whose serum cholesterol levels were greater than 300 mg/dL, especially in the group of women over 50 years of age.