Levothyroxine Replacement is Acceptable in Patients With Above the Upper Normal Range Lipid Profiles and Subclinical Hypothyroidism - Original Article

Abstract
Introduction: Subclinical hypothyroidism is a common disorder, particularly in middle-aged and elderly individuals. The aim of the present study was to determine the effect of L-thyroxine (LT4) substitution on serum lipid profile in patients with subclinical hypothyroidism (TSH > 4.5 μIU/mL and normal FT4).
Materials and Methods: Thirty-six female patients (mean age, 39 ± 9 yrs) with Hashimoto's thyroiditis were recruited in this study. The patients were separated into two groups according to their baseline lipid levels: group I, total cholesterol (TC)> 200 mg/dl (n=18); group II, low-density lipoprotein cholesterol (LDLc) >130 mg/dl (n=17). Thyroid hormone levels and lipid parameters were measured at baseline and after euthyroidism (TSH < 2.5 &mu;IU/mL) was achieved.
Results: Despite the fact that lipid profiles were not different between baseline and euthyroid conditions, TC and LDL levels were decreased significantly when euthyroidism was achieved (p<0.05) provided that the patients were separated into two groups according to their baseline lipid levels.
Discussion: TSH-guided LT4 therapy can improve lipid profile in patients with subclinical hypothyroidism if TC and/or LDLc levels were above the upper normal range.