Evaluation of leptin, neuregulin 4, FGF21, and vitamin D levels in patients with lichen planus

Objectives: Lichen planus (LP) is a chronic inflammatory skin disease associated with metabolic disorders. This study aimed to investigate the relationship between LP and metabolic diseases through the evaluation of insulin resistance, adipocytokines, and vitamin D levels in addition to routine biochemical tests. Methods: The study included 37 LP patients and 41 healthy controls. Serum fibroblast growth factor-21 (FGF-21), leptin, and neuregulin-4 (Ng-4) were measured using Enzyme-Linked Immuno Sorbent Assay (ELISA) methods. Levels of 25-hydroxyvitamin D (25-OH vitamin D) and were determined by chemiluminescence method on a Beckman Coulter DXI 800 (USA), while the glucose and lipid parameters were analyzed using photometric methods on a Beckman Coulter AU5800 Series (Japan). Results: Significant differences were observed between patients and controls in body mass index (BMI), triglycerides, high-density lipoprotein cholesterol (HDL-C), glucose, insulin, HOMA-IR, and Ng-4 (p<0.05). LP patients had higher BMI, triglycerides, glucose, insulin, and HOMA-IR, but lower HDL-C and Ng-4. In cases with both mucosal and cutaneous involvement, glucose and FGF-21 were significantly lower (p<0.05). ROC analysis for Ng-4 showed modest diagnostic value (AUC=0.624), with a cut-off of 7.127ng/mL (sensitivity 51.2%, specificity 73.7%). Conclusions: LP patients displayed impaired carbohydrate and lipid metabolism, characterized by increased glucose, insulin, triglycerides, HOMA-IR, and BMI, along with reduced HDL-C and Ng-4. Although FGF-21 and leptin did not differ significantly, subgroup analyses suggested potential roles in disease heterogeneity. Ng-4 alone showed limited diagnostic utility but may gain importance within a biomarker panel for LP-related metabolic disturbances.