Prevalence of Hashimoto's thyroiditis in psoriasis patients

To study the prevalence of Hashimoto's Thyroiditis in a sample of psoriasis patients.

Cross-sectional observational study of 120 individuals (60 with psoriasis and 60 control subjects) paired by gender and age for thyroid function (thyroid stimulating hormone, free T4), antithyroperoxidase and antithyroglobulin tests and physical examination. Psoriasis Area and Severity Index and Nail Psoriasis Severity Index were evaluated simultaneously. Epidemiological, clinical and treatment data was collected from medical records. Patients with documented hypothyroidism and/or goiter associated with positive antithyroperoxidase antibody were considered to have Hashimoto's Thyroiditis.

The prevalence of Hashimoto's Thyroiditis in the group with psoriasis was 21.6%; in the control group, it was 4/60 (6.6%) with p=0.03 (OR=3.8; 95%CI 1.18-12.6). In the group of patients with psoriasis, Hashimoto's Thyroiditis was more common in women (p=0.002) and less common in those who had polyarticular arthropathic psoriasis (p=0.05) and plaque psoriasis (p=0.005). A logistic regression showed that the only independent variable associated with Hashimoto's thyroiditis was plaque psoriasis.

There is a high prevalence of Hashimoto's Thyroiditis in psoriatic patients, especially in women. Hashimoto's Thyroiditis is less common in patients with the plaque form of psoriasis.