Thyroid function tests in cases of polymorphic light eruption: A case-control study

Background: Polymorphic light eruption (PLE) has been found to be associated with thyroid function abnormalities. Aim: To study clinicoepidemiological features of PLE and to study and compare thyroid function tests (TFTs) in cases of PLE. Materials and Methods: The study included 100 cases of PLE and age- and sex-matched controls attending a skin outpatient department. The clinical and epidemiological features were recorded. Both cases and controls were tested for thyroid-stimulating hormone (TSH). In case of abnormality in TSH, triiodothyronine (T3) and tetraiodothyronine (T4) levels were estimated. Results: TFT was abnormal in 25 cases and 7 controls. TSH was elevated in 24 cases and 6 controls and decreased in 1 case and 1 control. T3 and T4 were decreased in 18 cases and 6 controls and elevated in 1 each in case and control. Hypothyroidism was significantly high among cases than controls. Discussion: TFT abnormality was significantly higher among cases than controls. Hypothyroidism has a significant association with PLE. Genetic basis or immune dysfunction may be the cause of both the diseases. PLE may be considered as a clinical presentation of thyroid function disorder and vice versa. Conclusion: Cases of PLE should be examined clinically for thyroid disorder and also tested for TSH or TFT to find any association and prevent serious consequences.