Lipid profile and cardiovascular risk factors in patients with autoimmune hypothyroidism

Objectives. Autoimmune hypothyroidism is associated with disturbances in lipid metabolism. This study assessed lipid profiles and cardiovascular risk markers in patients with overt (OH) and subclinical hypothyroidism (SH) compared with healthy controls, and examined lipid changes during levothyroxine treatment. Methods. This observational case–control study included 129 adults: 65 patients with autoimmune hypothyroidism (35 OH, 30 SH) and 64 controls. All patients had complete lipid, TSH, and fT4 measurements at baseline, 8 weeks, and 16 weeks. Lipid indices included LDL cholesterol (LDL-c), HDL cholesterol (HDL-c), non-HDL cholesterol (non-HDL-c), and the total cholesterol/HDL-c ratio. Between-group comparisons and paired longitudinal tests were performed; longitudinal p values were not adjusted for multiple comparisons. Results. Baseline LDL-c was higher in patients than controls (3.96 ± 1.67 vs 3.39 ± 0.76 mmol/L; p = 0.015). Non-HDL-c was higher in OH than SH (5.31 ± 2.19 vs 3.64 ± 0.96 mmol/L), and the total cholesterol/HDL-c ratio was higher in patients than controls (4.16 ± 1.59 vs 3.42 ± 0.75; p = 0.001). At 16 weeks, mean LDL-c decreased from 3.96 ± 1.67 to 3.28 ± 1.00 mmol/L (p = 0.001), and non-HDL-c from 4.54 ± 1.92 to 3.68 ± 1.17 mmol/L (p < 0.001). HDL-c did not improve significantly. At week 16, TSH was within the reference interval in 42 of 65 patients (64.6%). Conclusions. Overt autoimmune hypothyroidism was associated with a more atherogenic lipid profile than SH or euthyroid status. During levothyroxine treatment, LDL-c and non-HDL-c improved, particularly in OH, while HDL-c did not. These observational findings do not establish a causal treatment effect or a reduction in cardiovascular events.