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

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

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.

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.

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.