Thyroxine Therapy Improves Serum Lipoproteins and Some Clinical Findings In Patients With Subclinical Hypothyroidism

Data on the effect of thyroxine therapy on lipid profiles and signs and symptoms of mild hypo-thyroid patients is controversial. This study was conducted to elucidate the issue. Material and Methods: In a single blind placebo control clinical trial, 80 patients with subclinical hypothyroidism (TSH> 5 m U/L on two occa-sions, positive anti TPO and normal FTI) were recruited and allocated into two groups by fixed block randomization (thyroxine therapy- 40 pa-tients and placebo- 40) The patients did not have any disease, nor were they taking any medica-tion influencing serum lipids and thyroid hor-mone levels. After physical examination, blood was drawn for measurement of serum TSH (IRMA), T4, T3, (RIA), and total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL) with enzymatic method by commercial kits before and after thy-roxine therapy and placebo. The adequacy of thyroxine therapy was documented by a normal TSH after 3 months. Data were statistically ana-lyzed by t test, paired t test and Fisher's exact test. Results: Attrition rate was 10 percent (72 patients followed completely). The mean ages in the therapy and placebo groups were 35.82 ± 12.3 yr and 36.3 ± 11.5 yr and the female to male ratio in each group was 36/4 and 26/6 respectively. There was no significant difference in the BMI of the two groups (28.1 ± 5.5 vs. 25.9 ± 3.7 Kg/m2 respec-tively). The mean of lipid profile and thyroid hormones were not significantly different in the two groups before intervention. The mean dif-ference of total cholesterol (18.27 ± 30.7 vs. 1.5 ± 33.8 mg/dL, p= 0.019) and LDL (22.45 ± 28.4 vs. 2.08±37.0 mg/dL, p= 0.005) before and after ther-apy between the two groups were significant. Triglyceride levels and HDL were not signifi-cantly changed in both groups. With regard to clinical findings, only skin dryness and fatigue were significantly improved with thyroxine therapy (p<0.05). Conclusion: There is a significant decrease in se-rum total cholesterol and LDL levels and im-provement of some clinical findings in patients with subclinical hypothyroidism treated with levothyroxine.