Exploring hypothyroidism's effects on lipid profiles: Evidence of metabolic consequences in subclinical disease.

Objectives: To investigate the association between thyroid-stimulating hormone (TSH) levels and lipid profiles in patients with subclinical hypothyroidism (SCH) to assess the metabolic risks.

Methods: This retrospective study included patients diagnosed with SCH between January 2023 and August 2024. Thyroid function markers (TSH, free triiodothyronine, and free thyroxine levels) and lipid profiles (total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglyceride levels) were assessed in 137 patients.

Results: The mean age of patients was 44.6±13.6 years, with 86.1% being female and 92.7% having dyslipidemia. Thyroid-stimulating hormone levels were correlated with serum creatinine levels (r=0.27, p=0.001) and showed a non-significant trend toward higher cholesterol levels (r=0.15, p=0.09). Free thyroxine were significantly lower in women (p=0.035) and in patients with hypertriglyceridemia (n=32; p=0.005), showing an inverse correlation (r= -0.2; p=0.02). Free triiodothyronine were lower in patients with obesity (p=0.003) and inversely associated with body mass index (BMI, r= -0.2, p=0.019). Serum creatinine levels independently predict TSH levels, whereas triglyceride levels inversely predict free thyroxine levels.

Conclusion: Subclinical hypothyroidism impairs lipid metabolism, particularly in females with high BMI. Triglycerides suppress free thyroxine levels, whereas elevated TSH levels correlate with increased creatinine levels. Our findings suggest a potential relationship between SCH and lipid alterations, warranting further investigation into targeted lipid management in these patients.