EVALUATING THYROID HORMONE INFLUENCE ON CARDIOVASCULAR RISK AMONG PATIENTS WITH SUBCLINICAL AND CLINICAL HYPOTHYROIDISM

Background: Thyroid hormones exert critical effects on cardiovascular physiology, and both subclinical and clinical hypothyroidism have been implicated in adverse cardiac outcomes. Evidence suggests varying degrees of cardiovascular risk depending on the stage of hypothyroidism, yet data from South Asian populations remain limited. Objective: To assess how varying thyroid hormone levels influence cardiovascular health among patients with subclinical and clinical hypothyroidism. Methods: This cross-sectional study was conducted over eight months at a tertiary care hospital in Lahore, Pakistan, involving 310 adults—155 with subclinical hypothyroidism and 155 with clinical hypothyroidism. Diagnosis was based on serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels. Cardiovascular assessment included clinical evaluation, electrocardiography, and echocardiography. Laboratory investigations comprised lipid profile and high-sensitivity C-reactive protein (hs-CRP). Statistical analyses were performed using t-tests, ANOVA, chi-square tests, and multiple linear regression, with p<0.05 considered significant. Results: Participants with clinical hypothyroidism exhibited higher prevalence of left ventricular diastolic dysfunction (35.5% vs. 21.3%), systolic dysfunction (14.8% vs. 6.5%), and atrial fibrillation (12.3% vs. 8.4%) compared to subclinical cases. Elevated blood pressure was more frequent in the clinical group (45.8% vs. 32.9%). Total cholesterol and LDL-C were significantly higher in clinical hypothyroidism (228.5 mg/dL and 148.9 mg/dL) than in subclinical disease (210.4 mg/dL and 137.8 mg/dL). hs-CRP levels were also higher in the clinical group (4.1 mg/L vs. 3.4 mg/L). Conclusion: Cardiovascular risk factors and structural abnormalities were more pronounced in clinical hypothyroidism, underscoring the need for proactive cardiovascular screening in all hypothyroid patients, with greater vigilance in overt disease.