Biochemical Correlation of Thyroid Dysfunction Among Patients Presenting With Polymorphic Light Eruption.

Objective The pathophysiology of polymorphic light eruption (PMLE) is uncertain; however, it is considered to commonly involve an autoimmunological mechanism. It is a common condition, usually affecting subjects staying at temperate latitudes, and presents with eruptions post-exposure to sunlight and artificial UVR (ultraviolet radiation), lasting from hours to, in rare cases, days of exposure. This present study aims to compare biochemical thyroid function tests in cases of PMLE.  Methodology The present case-control study was conducted with a total of 120 participants. Patients with polymorphic light eruption aged 18 years or above of either sex attending the dermatology outpatient department were included in the study. TSH (thyroid-stimulating hormone), T3 (triiodothyronine), and T4 (thyroxine) were analyzed among the participants. The data was recorded on a Microsoft Excel spreadsheet and analyzed using SPSS Statistics v. 21 (IBM Corp., Armonk, NY). The qualitative data was assessed in the form of numbers and percentages and the quantitative data was assessed using measures of central tendency such as mean and standard deviation. A chi-square test was applied to find out the association and their strength between the variables to validate the findings of the study. A p-value <0.05 was considered to be statistically significant. Results The TSH was elevated in 56 (93.3%) cases and two (3.3%) among the controls; T3 and T4 were low in 24 (40%) cases, and in seven (11.7%) among the controls. Conclusion PMLE usually has an autoimmune basis for its occurrence; similarly, thyroid disorders being themselves autoimmune in origin might lead to hypersensitivity reactions and generation of autoantibodies. We suggest that screening for thyroid should be conducted for all PMLE patients as they are at higher risk of developing thyroid disorders. The relationship between the two should be studied with a much larger cohort of participants to evaluate whether this is autoimmune-related or accidentally related.