Effect of L-thyroxine treatment versus a placebo on serum lipid levels in patients with sub-clinical hypothyroidism

Abstract

Abstract. Sub-clinical hypothyroidism is a common disease and whether L-thyroxine replacement treatment improves serum lipid levels in affected patients remains controversial. Thus, the aim of the present meta-analysis was to assess the effect of L-thyroxine therapy on serum lipid levels in sub-clinical hyperthyroidism. Relevant randomized controlled trials (RCTs) containing continuous data, published until July 2015 were retrieved from the Cochrane Library, PubMed, Medline, Google Scholar and Embase databases and subjected to meta-analysis using Review Manager software version 5.2 (The Nordic Cochrane Centre, Copenhagen, Denmark). Seven RCTs comprising 319 patients were included. The overall methodological quality of the RCTs was good. Statistical analysis revealed that serum low-density lipoprotein-cholesterol (LDL-C) levels were significantly decreased after L-thyroxine treatment [mean difference (MD): -0.23; 95% confidence interval: -0.44, -0.03; P= 0.02], while changes of total cholesterol (TC), triglyceride (TG) and high-density lipoprotein-cholesterol (HDL-C) were not significant P= 0.09; P= 0.78; P= 0.14, respectively). In conclusion, the meta-analysis performed in the present study revealed that compared with placebo treatment, L-thyroxine significantly improved serum LDL-C levels in patients with sub-clinical hypothyroidism, while not significantly affecting TC, TG and HDL-C levels.

Thyroid disease and the metabolic syndrome

“…Observational studies also report the association of SCH with high triglycerides, total cholesterol (TC) and LDL cholesterol (LDL-C) even in mild SCH [112,113]. Data regarding the effects of levothyroxine therapy on lipid profiles in SCH patients were heterogeneous and a few reported significant improvement in lipid profile [114], in a recent meta-analysis L-thyroxine significantly improved LDL-C levels in patients with SCH, while not significantly affecting TC, triglycerides and HDL-C levels [115].…”