Background: Alopecia areata (AA) is a complex, multifactorial autoimmune disease in which a person's genetic predisposition plays a significant role. Alopecia areata has been linked to various autoimmune conditions. There is a significant likelihood that autoimmune thyroid disorders will coexist with these conditions.

Objectives: To determine the association between alopecia areata and subclinical thyroid dysfunction, and to assess serum cortisol levels and their relationship with AA.

Methods: ‏The case-control study, conducted at the Dermatology Center of Baghdad Teaching Hospital from October 2023 to February 2024, involved 80 AA patients and 40 healthy controls. Thyroid hormones and cortisol levels were measured using electrochemiluminescence immunoassay.

Results: The mean age of AA patients was (29.4±10.49) years compared to (30.1±8.77) years in controls, with no statistically significant difference (p=0.75). Serum T3 levels were significantly higher in AA patients (1.5 ± 0.04 ng/ml) compared to controls (1.4 ± 0.03 ng/ml, p=0.03), though all values remained within the normal range. In contrast, no significant differences were observed in T4 levels (8.4 ± 0.21 vs. 8.7 ± 0.16 μg/dl, p=0.25) or TSH levels (1.7 ± 0.11 vs. 1.6 ± 0.08 μIU/ml, p=0.31) for the AA and controls respectively. Serum cortisol levels were significantly higher in AA patients (11.1 ± 0.52 ng/dl) compared to controls (8.6 ± 0.23 ng/dl, p<0.0001). However, all measured cortisol levels in both groups remained within the normal reference range.

Conclusion: Significant differences in T3 and cortisol levels exist between alopecia patients and controls, suggesting hormonal involvement in AA. No significant differences were found in T4 and TSH levels, requiring further investigation