Autoimmune Thyroid Disease in Psoriasis Patients: A Case-Control Study

Introduction: Psoriasis is a common immunologically mediated inflammatory disease characterized by skin inflammation, epidermal hyperplasia, an increased risk of painful and destructive arthritis, cardiovascular morbidity, and psychosocial challenges. Some autoimmune diseases are mediated by stimulating or blocking auto-antibodies. Auto-antibodies may act as antagonists and bind to hormone receptors, blocking receptor function. It may result in impaired secretion of mediators and gradual dysfunction of the affected organ, e.g., Graves disease and myasthenia gravis.Objective: This study was planned to evaluate the association between anti-thyroid peroxidase antibody (anti-TPO Ab) and anti-thyroglobulin antibody (anti-TG Ab) as biochemical markers in 30 clinically diagnosed psoriasis patients.Materials and methods: This hospital-based, epidemiological case-control study was conducted in the Department of Biochemistry in collaboration with the Department of Dermatology, Venereology, and Leprology at Bhagat Phool Singh Government Medical College for Women, Khanpur Kalan, Sonepat, Haryana, India. Thirty subjects diagnosed clinically with psoriasis and an equal number of age-matched controls with no known autoimmune disease from the outpatient department were also enrolled. The following hormonal tests, i.e., thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), and antibodies, anti-TPO Ab and anti-TG Ab, were performed. The study period was one year. The data thus obtained was analyzed using SPSS Statistics version 26.0 (IBM Corp. Released 2019. IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp). The significance level (p-value) was taken as <0.05.Results: The mean age of psoriasis subjects was 37.83 +/- 12.89 years compared to 36.91 +/- 12.32 years in the control group and was found to be non-significant (p=0.432), reflecting a similar age distribution. A male preponderance was observed in the present study, where the psoriasis group consisted of 80% males and 20% females, while the control group had 60% males and 40% females. All six psoriasis patients diagnosed with autoimmune thyroid disease (AITD) were euthyroid at the time of enrollment, compared to only one control subject in a subclinical hypothyroid state. The mean values of anti-TPO Ab were 30.93 +/- 41.26 IU/mL in psoriasis patients and 11.39 +/- 28.42 IU/mL in the control group (p=0.001), while the mean values of anti TG Ab were 11.21 +/- 27.69 IU/mL in psoriatic subjects and 2.49 +/- 9.05 IU/mL in the control group (p=0.004). No significant correlation between AITD and psoriasis was found when both parameters were analyzed statistically for correlation; even when one marker was considered, no significant correlation was found. The odds ratio was calculated to find an association between the disease and thyroid autoimmunity. The odds ratio was estimated to be 2.25 for psoriasis and the control group, with a confidence interval of 95% (0.77-6.59) and a p-value of 0.139, which was not statistically significant.Conclusion: Psoriasis, a dermatological disorder, has been seen as related to AITD. The role of early detection of anti-thyroid antibodies, i.e., anti-TPO Ab and anti-TG Ab, can be of prognostic value in AITD and psoriasis.