Serum Irisin Level Among Patients with Subclinical Hypothyroidism in Relation with Plasma Atherogenic Indices

Background and objectives: Subclinical hypothyroidism, impacting 3-8% of the general population with a higher incidence in women and older individuals, is linked to cardiovascular and atherosclerosis. This study evaluated the serum irisin levels in individuals with newly diagnosed subclinical hypothyroidism compared to a control group, explored its association with atherogenic plasma indices. Methods: A case-control study, enrolled 160 participants, including 80 with newly diagnosed subclinical hypothyroidism and 80 euthyroid individuals as controls. The study was conducted at the Endocrine Department of Rzgary Teaching Hospital in Erbil City, Iraq. The study was conducted between September 2022 - September 2023. Blood samples were collected for measurement of serum irisin levels, thyroid hormones, lipid profile, anti- thyroid peroxidase antibodies, and atherogenic indices. Results: Notably, 76.3% of Subclinical Hypothyroidism cases were young females (<40, p<0.001) with higher rates of overweight/obesity (73.8%) compared to controls (p<0.001). Waist circumference and thyroid hormone levels were significantly higher in subclinical hypothyroidism cases (p<0.001). The prevalence of high atherogenic coefficient was higher in cases (83.7% vs. 63.8%, p=0.004). Thyroid stimulating hormone levels were elevated in subclinical hypothyroidism cases (7.37?-IU/mL) compared to controls (2.67?-IU/mL) (p < 0.001). Anti- thyroid peroxidase antibodies titer was significantly higher in cases (54.37 IU/mL) than controls (16.55 IU/mL) (p < 0.001). Conclusions: Subclinical hypothyroidism is prevalent among young obese females. Serum irisin levels remain steady in subclinical hypothyroidism compared to healthy controls but positively correlate with atherogenic indices in these patients.