Thyroid involvement in ankylosing spondylitis and relationship of thyroid dysfunction with anti-TNF α treatment.

Association between rheumatological and autoimmune thyroid disorders has been demonstrated by many studies. However, a few data exist indicating the association between thyroid disorders and ankylosing spondylitis (AS). In this study, the frequency of thyroid disorders in patients with AS and the impact of anti-TNF α therapy on this were investigated. Data of 108 patients (female/male (F/M) 27/81) were analyzed. Data on free T3, free T4, thyroid-stimulating hormone, anti-thyroid peroxidase antibodies (TPO), anti-thyroglobulin antibodies, and thyroid ultrasound were assessed retrospectively. 44 (F/M 15/29) patients were receiving anti-TNF α, while 64 (F/M 12/52) were receiving other drugs [(sulfasalazine, anti-inflammatory drug (NSAIDs)]. Among those not receiving anti-TNF α therapy, TPO level was high in 23 patients (mean TPO value 86.69 ± 65.28 U/ml), while it was high only in nine receiving anti-TNF α (mean TPO 36.61 ± 14.02 U/ml) (p < 0.05). Investigating the data regarding gender in both populations, autoimmune thyroid disease frequency was found to be lower in the patient group receiving anti-TNF α treatment. Subclinical hyperthyroidism was discovered in three patients (one female two male), and subclinical hypothyroidism in two (two male). Thyroid nodule was detected in 29 patients. It was concluded that the frequency of thyroid autoimmune disease was higher in our study than that reported in the literature, and the frequency of thyroid disorder in patients with AS was lower in those receiving anti-TNF α compared to those not. This may arise from the role of TNF α on pathogenesis of thyroid disorders.