Supplementary Material for: Association between Serum Trace Elements and Telogen Effluvium: A Systematic Review and Meta-Analysis

Background: Telogen effluvium (TE) affects the scalp and is marked by widespread, non-scarring hair loss systematic review and meta-analysis aim to evaluate the association between these micronutrients and TE across different age groups. Eligible studies included RCTs, clinical trials, cohort, case-control, and cross-sectional studies that reported serum levels of zinc, copper, or vitamin D in TE patients versus healthy controls. Meta-analyses were conducted using RevMan 5.3 with a random-effects model; heterogeneity was assessed via I² and Chi² statistics. Summary: Out of 372 papers, 29 articles were considered suitable for the systematic review extracted through the database search. Diagnostic methods included trichoscopy and standardized assays (e.g., AAS, ICP-MS). This review analyzed TE patients as predominantly female. Meta-analyses revealed significantly lower serum ferritin (SMD = -0.57, 95% CI: -1.01 to -0.12, p = 0.01) and vitamin D (SMD = -0.87, 95% CI: -1.49 to -0.25, p = 0.006) levels in TE cases versus controls. Key Message: TE is strongly associated with deficiencies in ferritin and vitamin D. Despite high heterogeneity, findings underscore the role of trace element imbalances in hair loss. Personalized nutritional interventions and standardized diagnostic protocols are recommended to address variability and improve clinical outcomes.