Postprandial hyperlipidemia in overt and subclinical hypothyroidism.

BACKGROUND AND AIMS

Lipid alterations in overt hypothyroidism (OH) were well known, but its changes in subclinical hypothyroidism (SCH) and postprandial period were not clear. The aim of this study is to evaluate postprandial lipemia by oral lipid tolerance test (OLTT) in patients with OH and SCH.

MATERIALS AND METHODOLOGY

Twenty-five OH and 27 SCH, totally 52 hypothyroid patients [mean age 38.3 ± 12.8 year, body mass index (BMI): 29.0 ± 5.8 kg/m(2)] and 23 BMI- and age-matched healthy controls (mean age 36.7 ± 11.9 years; BMI: 27.1 ± 6.9 kg/m(2)) were included to the study. Anthropometric measurements and HOMA-IR levels were measured. Basal and postprandial lipid profile at 2nd, 4th, 6th and 8th hours were determined by oral lipid tolerance test.

RESULTS

There were not any statistical differences among three groups (control, OH and SCH) in terms of mean fasting levels of total cholesterol, LDL-cholesterol, VLDL-cholesterol, and triglyceride. On the contrary, mean triglyceride levels at postprandial 8th hour in both OH and SCH patients were higher than control subjects (p=0.017 and p=0.049, respectively). Again mean postprandial 8th hour VLDL-cholesterol levels in OH group were also higher than control subjects (p=0.05). In addition mean HOMA-IR value of SCH and OH patients was similar with control subjects (1.5 ± 1.4 in OH; 1.3 ± 0.8 in SCH; 2.2 ± 2.2 in control group).

CONCLUSIONS

Although total, LDL and VLDL-cholesterol, and triglyceride levels were not different from healthy controls, triglyceride and/or VLDL-cholesterol levels apparently increased with OLTT in both OH and SCH patients. Decreased lipid clearance may be responsible for this result.