Scalp Seborrheic Dermatitis Severity Is Associated with Lipid and Liver-Associated Biochemical Parameters

Introduction: Seborrheic dermatitis (SD) is a lipid-dependent inflammatory dermatosis in which sebaceous activity, Malassezia, barrier dysfunction and host inflammation interact. Whether scalp SD severity is associated with systemic lipid and liver-associated biochemical parameters remains unclear. Methods: In this exploratory cross-sectional observational study, we included 34 adults with clinically diagnosed scalp SD. Severity was assessed using a published 16-point scalp SD score and a study-specific 0-36 physician-assessed score. Fasting lipids, glucose, alanine aminotransferase (ALT), aspartate aminotransferase and gamma-glutamyl transferase (GGT) were recorded. The triglyceride/high-density lipoprotein cholesterol ratio and non-HDL cholesterol were calculated. Patients were stratified as having non-severe or severe disease according to the 16-point score. Results: Complete 16-point data were available in 33 patients: 15 with non-severe and 18 with severe scalp SD. Severe disease was associated with higher triglycerides (116.0 vs. 78.0 mg/dL; p = 0.004), triglyceride/high-density lipoprotein cholesterol ratio (2.57 vs. 1.23; p = 0.006), ALT (46.0 vs. 20.0 U/L; p = 0.028) and GGT (33.0 vs. 11.0 U/L; p = 0.003). The strongest correlations with the 16-point score were observed for GGT (rho = 0.745), triglycerides (rho = 0.634), ALT (rho = 0.572) and triglyceride/high-density lipoprotein cholesterol ratio (rho = 0.569; all p < 0.001). These prespecified associations remained significant after false-discovery-rate adjustment and after adjustment for age and BMI. The correlation pattern was strengthened using the 0-36 score and persisted after excluding one liver enzyme outlier. Conclusions: More severe scalp SD was associated with triglyceride-related lipid parameters and liver-associated enzymes, suggesting a broader lipid-liver metabolic phenotype. These findings require confirmation in larger controlled studies.