Association between different degrees of hypothyroidism and serum lipids

Abstract

The association between overt hypothyroidism (OH) and altered lipid profile is well known, however the significance of dyslipidemia in subclinical hypothyroidism (SCH) remain controversial. Therefore, this study was conducted to determine any association between lipid profile and different degrees of thyroid dysfunction. Thyroid and lipid profile parameters were analysed in 58 patients with overt (TSH ≥ 10.0 μIU/L and/or abnormally low fT4 and fT3 levels) and 87 patients with subclinical hypothyroidism (TSH 6.0-9.9 μIU/L with normal fT4 and fT3 levels) in this case-control study. These were compared with 100 age- and sex-matched euthyroid controls. It was found that only mean serum level of total cholesterol in patients with SCH was significantly high from that in controls (p=0.045). Other lipid parameters did not show any statistical significance. Whereas patients with OH had statistically significant higher levels of total cholesterol (p<0.001), triglyceride (p<0.05), LDL-C (p<0.001) and VLDL-C (p<0.05). There was also an increase in HDL-C in both SCH and OH group though not significant statistically. In conclusion, lipid profile is not much deranged in SCH whereas OH is a major cause of secondary dyslipidemia which may lead to increased risk of coronary artery disease. Therefore, thyroid hormone replacement would be most beneficial in patients with OH instead of SCH. However, patients with SCH should be monitored for deterioration of thyroid function and dyslipidemia at regular intervals.

Keywords: Cholesterol; Dyslipidemia; HDL cholesterol; Hypothyroidism; Subclinical

Internet Journal of Medical Update 2012 July;7(2):3-8