Relationship between Different Psoriasis Types and Thyroid Dysfunction: A Retrospective Analysis

OBJECTIVE: The aim of this study was to investigate the relationship between different psoriasis types and thyroid dysfunction. METHODS: The data of patients diagnosed with psoriasis between January 2013 and October 2018 who underwent thyroid function tests were collected. Free triiodothyronine (FT3), free thyroxine (FT4), total triiodothyronine (TT3), total thyroxine (TT4), thyroid-stimulating hormone (TSH), thyroglobulin antibody (TGAb), and thyroid peroxidase antibody (TPOAb) were measured. The thyroid function of patients with psoriasis vulgaris, pustular psoriasis, erythrodermic psoriasis, and psoriatic arthritis was evaluated, and the differences in hormone levels and antibodies in the pituitary-thyroid axis with psoriasis type were analyzed. RESULTS: The data of a total of 468 patients were analyzed in this study. The proportion of normal hormone levels was higher among vulgaris patients (P < 0.001), while the erythrodermic patients were more likely to have decreased FT3 or FT4 but normal TSH (P < 0.001). FT3 levels were lower in pustular patients (P < 0.05), FT4 levels were lower in erythrodermic patients (P < 0.05), and TSH levels were higher in patients with psoriatic arthritis (P < 0.05). TPOAb levels were higher than normal in all patients, but there was no significant difference in the levels of TPOAb and TGAb among 4 types of the patients. CONCLUSION: Psoriasis is related to thyroid dysfunction, especially in patients with atypical psoriasis types. The possibility of complications should be considered in erythrodermic patients.