Effect of levothyroxine in the treatment of primary hypothyroidism

Objective To explore the influence of levothyroxine(L-T4) in the treatment of primary hypothyroidism on myocardial enzymes and lipids.Methods 78 patients with primary hypothyroidism were selected and treated with L-T4 for 12 weeks.The fasting serum levels promote thyroid hormone(TSH),free T3 (FT3),free T4 (FT4),total cholesterol (TC),triglycerides (TG),low-density lipoprotein cholesterol (LDL-C),aspartate aminotransferase enzyme (AST),creatine kinase (CK) and its isoenzyme (CK-MB),lactate dehydrogenase(LDH) were monitored and analyzed before and after treatment.Results After L-T4 treatment for 12 weeks,compared with before treatment,TSH,TC,TG,LDL-C,CK,CK-MB,LDH,AST were significantly decreased or restored (t =10.5223,26.8498,22.7699,16.2735,22.9329,13.1910,32.0907,22.9597,all P ＜ 0.01).The FT3 was negatively correlated with TG (r =-0.3782),LDL-C(r =-0.3506),AST(r =-0.2843),LDH(r =-0.2974),CK(r =-0.3726) (all P ＜ 0.01)and CK-MB(r =-0.2559) (P ＜ 0.05).FT4 was negatively correlated with TC (r =-0.2660),TG (r =-0.4661),LDL-C(r=-0.5119),LDH(r=-0.5936),CK(r=-0.4877),CK-MB(r=-0.5463) (all P＜0.01)and AST(r =-0.2328) (P ＜0.05).TSH was positively correlated with TC(r =0.5341),TG(r =0.7567),LDL-C(r =0.8240),AST (r =0.3923),LDH (r =0.8073),CK (r =0.9661),CK-MB (r =0.7336) (all P ＜0.01).TSH had,the best correlationship with CK (r =0.9661).Conclusion L-T4 can significantly improve the thyroid function and reduce the blood lipids,myocardial enzymes levels of patients with primary hypothyroidism. Key words: Hypothyroidism ; Thyroxine ;  Myocardium enzymes;  Lipids