The Relationship Between Lichen Planus and Thyroid Disorders in an Iranian Population: A Case-Control Study.

BACKGROUND AND AIMS: Previous research investigated the connection between lichen planus (LP) and thyroid disorders due to their autoimmune characteristics; however, the correlation remains unclear. This study investigates the relationship between thyroid disorders and specific subtypes of LP, particularly cutaneous lichen planus (CLP) and lichen planopilaris (LPP), to determine the need for thyroid screening in LP patients. METHODS: This case-control study at Razi Hospital's skin clinic (2023-2024) involved 70 LP patients and 70 controls. A dermatologist confirmed the diagnosis via clinical evaluation and biopsy. Medical histories, medication, and BMI were collected. Serological tests for thyroid disorders were conducted, and patients were categorized accordingly. Data analysis was performed using SPSS version 22. RESULTS: The study shows a significant link between LP and thyroid disorders (p = 0.007), consistent across LP subtypes (CLP and LPP). LP patients had higher TSH (p = 0.008) and anti-TPO antibody levels (p < 0.001), while free T4 levels were lower but not statistically significant (p = 0.38). Anti-TPO antibody levels were significantly elevated in both LP subtypes (p = 0.01 in CLP and p = 0.002 in LPP) compared to controls. Age, gender, BMI, and T3 levels did not significantly correlate with LP. Longer LP duration was associated with higher TSH levels (p = 0.05). CONCLUSION: There is a significant relationship between LP and thyroid disorders, particularly hypothyroidism. These findings advocate for regular thyroid function monitoring in LP patients to facilitate early detection and management of thyroid issues.