Hashimoto's Hypothyroidism is the Common Comorbidity
The correct answer is B) Hashimoto's hypothyroidism, which shows one of the strongest associations with alopecia areata among autoimmune comorbidities.
Evidence for Thyroid Disease Association
Hashimoto's thyroiditis demonstrates a particularly strong association with alopecia areata, with an odds ratio of 4.31 (95% CI 2.51-7.40) compared to healthy controls 1. This represents one of the highest risk associations among all comorbid conditions studied in AA patients.
Strength of the Association
A nationwide population-based study found that AA patients had significantly increased risk of Hashimoto thyroiditis (OR 1.157,95% CI 1.081-1.237), with even stronger associations in severe AA cases (OR 1.398,95% CI 1.137-1.719) 2
The association between AA and autoimmune thyroid disease is so well-established that screening for thyroid function is recommended even in the absence of clinical manifestations 3
Among patients with AA, subclinical hypothyroidism was detected in 16% of cases, with statistically significant differences in TSH, free T3, and free T4 levels compared to controls 3
Clinical Implications
Both anti-thyroglobulin antibody (Tg-Ab) and anti-thyroid peroxidase antibody (TPO-Ab) show significantly higher prevalence in AA patients compared to controls 3
The British Journal of Dermatology recommends checking TSH levels to rule out thyroid disease in patients with hair loss 4
If biochemical hypothyroidism is confirmed with high TSH and low free T4, thyroid peroxidase (TPO) antibody testing is warranted 4
Why Other Options Are Incorrect
Chronic headache (A): No significant association with AA has been established in the literature provided
Polycystic ovary syndrome (C): While PCOS can cause hair loss, it is mentioned only in the context of testing for androgen excess in women with androgenetic alopecia, not as a comorbidity of AA 4
Type 2 diabetes mellitus (D): Although mentioned as a potential associated condition, it does not show the same strength of association as Hashimoto's thyroiditis 5
Shared Autoimmune Pathophysiology
The strong association between AA and Hashimoto's thyroiditis reflects their shared autoimmune mechanisms, where T lymphocytes mediate tissue-specific autoimmune reactions 4, 6. This explains why approximately 20% of AA patients have a family history of autoimmune diseases 4.