Sever hypothyroidism Effect of L- thyroxine therapy on the lipid contents of serum lipoproteins

ABSTRACT

Thyroidal status has s well known effect on lipid metabolism. Thyroid insufficiency may cause secondary hyperlipidemia, but effect of short course [pound l2 weeks] L-thyroxine therapy on elevated high density lipoprotein cholesterol [HDL-c] is controversial. Particularly the effect of short course of L-thyroxine therapy on elevated levels of various serum lipoproteins in severely hypothyroid patients.[serum T[4] levels <15 mmol/L and hTSH >150 mU/L] has not been established. To assess the efficacy of L-thyroxine therapy in normalizing the elevated lipid contents of various serum lipoprotein fractions in severe primary hypothyroidism in the local population. DESIGN: Controlled clinical trial. PATIENTS AND METHODS: 17 male patients referred to Punjab Institute of Nuclear Medicine, Faisalabad, mean age [mean age 32 +/- 18 years, ranging 23-67 years], having serum levels of T[4] <15 mmol/L and hTSH >150 mU/L were selected. pre-therapy fasting blood samples was taken at the time of diagnosis. All subjects became euthyroid after 9 weeks of L-thyroxine therapy with gradual increase of dosing from 50 to 150 [micro] g/d. Post-therapy fasting blood was taken after 12 weeks of L-thyroxine therapy. With L-thyroxine therapy euthyroid state was achieved within 9 weeks and all patients became free from signs and symptoms of hypothyroidism. Serum triacylglycerols, total cholesterol and LDL-c levels were reduced significantly [P <0.01] but there was a slight reduction in the serum HDL-c levels. CONCLUSIONS: L-thyroxine therapy in severe hypothyroidism does have a cardioprotective effect by normalizing the elevated levels of TAGs, total cholesterol and LDL-c