Evaluation of Lipid Profile Disturbances in Patients with Thyroid Dysfunction: A Case-Control Study

Thyroid disorders are among the most common endocrine diseases worldwide and are frequently accompanied by disturbances in blood lipid metabolism, creating an atherogenic profile that increases cardiovascular risk. This study aimed to evaluate selected thyroid hormones and lipid parameters in patients with thyroid disorders compared with apparently healthy individuals. This case–control study enrolled 100 participants aged 21–74 years, divided into 50 patients with clinically and biochemically confirmed thyroid dysfunction and 50 apparently healthy controls with normal thyroid function. Serum TSH, total T3, and total T4 were measured using the Cobas e411 automated immunoassay analyzer, while total cholesterol, triglycerides, and HDL-cholesterol were determined using the Mindray BS-120 clinical chemistry analyzer, with LDL-C and VLDL-C calculated by the Friedewald equation. Data were analyzed using SPSS version 26, employing the independent-samples t-test, Chi-square test, and Pearson's correlation coefficient, with P < 0.05 considered significant. The three groups were comparable in age (F(2,97) = 0.586, P = 0.559) and sex (χ²(2) = 1.138, P = 0.566). Serum TSH differed significantly among the groups (H(2) = 81.163, P < 0.001), being markedly elevated in the hypothyroid group (median 7.39 mIU/L) and suppressed in the hyperthyroid group (median 0.06 mIU/L) relative to healthy controls (median 1.50 mIU/L), with T4 and T3 showing the expected inverse pattern (both P < 0.001). Both hypothyroid and hyperthyroid patients exhibited significantly higher total cholesterol, triglycerides, LDL-C, and VLDL-C, together with lower HDL-C, than healthy controls (all P ≤ 0.001), with no significant difference between the two patient subgroups, while correlations between thyroid hormones and lipid fractions were weak and non-significant in both subgroups (rₛ ranging from −0.366 to 0.475). In conclusion, thyroid dysfunction, predominantly hypothyroidism, was associated with a clinically meaningful atherogenic dyslipidemia linked to the categorical presence of the disorder rather than to a linear hormone–lipid relationship, supporting the routine evaluation and management of the lipid profile in patients with thyroid disorders.