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 hypothyroid 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 ufl on two occasions, positive anti tpo and normal fri) were recruited and allocated into two groups by fixed block randomization (thyroxine therapy- 40 patients and placebo- 40) the patients did not haveany disease, nor were they taking any medication influencing serum lipids and thyroid hormone levels. after physical examination, bloodwas 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 thyroxine therapy and placebo. the adequacy ofthyroxine therapy was documented by a normal tsh after 3 months. data were statistically analyzed by t test, paired t test and fisher's exacttest. results: attrition rate was 10 percent (72 patients followed completely). the mean ages in the therapy and placebo groups were 35.82 ± 12.3 yrand 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 kglrn2 respectively).the mean of lipid profile and thyroid hormones were not significantly different in the two groups before intervention. the mean differenceof 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 therapy between the two groups were significant. triglyceride levels and hdl were not significantly changed in both groups. with regard toclinical findings, only skin dryness and fatigue were significantly improved with thyroxine therapy (p<0.05).conclusion: there is a significant decrease in serum total cholesterol and ldl levels and improvement of some clinical findings in patientswith subclinical hypothyroidism treated with levothyroxine.