Endocrine Abstracts

Objective: To investigate the relationship between serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) and body mass index (BMI), blood glucose, serum lipids and liver in overweight and obese euthyroid healthy premenopausal women and euthyroid women with autoimmune thyroiditis on levothyroxine replacement therapy.

Patients and methods: The study includes 34 premenopausal women with autoimmune hypothyroidism on stable levothyroxine dose and 129 aged-matched healthy premenopausal women. All women had TSH within reference range (0.4-4.2 mIU/l) and were overweight or obese (BMI 25-40 kg/m²) without pre-existing diabetes. Fasting blood glucose, ASAT, ALAT, total cholesterol, HDL, triglycerides were measured and LDL was calculated.

Results: Women on levothyroxine had higher levels of TSH (2.55±1.02 vs 2.02±0.89 mIU/l, P0.009) and FT4 (11.58±1.63 vs 10.80±1.36 pmol/l, P0.007) compared to healthy controls. No differences between BMI and the investigated laboratory parameters were found between treated and healthy women. In women with treated hypothyroidism no correlations between TSH and BMI, blood glucose, lipids and liver enzymes were established. FT4 showed significant negative relation with total (r=-0.547, P0.001) and LDL cholesterol (r=-0.553, P0;001). In euthyroid control group positive correlation between TSH and BMI was found (r=0.291, P0.001). FT4 levels did not affect the investigated parameters.

Conclusion: Obesity, blood glucose and lipids are not associated with TSH levels within the target range in premenopausal women with autoimmune thyroiditis on replacement therapy. In healthy women TSH variations within reference range are associated with higher BMI but do not have significant influence on features associated with high risk of metabolic syndrome.