Serum zinc, copper, and copper–zinc ratio in psoriasis: association with disease severity

Abstract

Background: Psoriasis is a chronic immune-mediated inflammatory skin disorder in which oxidative stress and immune dysregulation play key pathogenic roles. Trace elements such as zinc and copper are essential for antioxidant defense and immune function, and their imbalance—often expressed as the copper–zinc (Cu/Zn) ratio—has been implicated in various inflammatory conditions. However, evidence regarding their association with psoriasis severity remains inconclusive.

Aim: To evaluate serum zinc, copper, and Cu/Zn ratio in patients with psoriasis and to assess their association with disease severity as measured by the Psoriasis Area and Severity Index (PASI).

Materials and Methods: This hospital-based cross-sectional observational study included 50 adult patients with clinically diagnosed psoriasis attending a tertiary care teaching hospital in South Gujarat, India. Disease severity was assessed using PASI scoring. Fasting serum zinc and copper levels were measured using atomic absorption spectrophotometry, and the Cu/Zn ratio was calculated. Data normality was assessed using the Shapiro–Wilk test, and non-parametric statistical methods were applied. Associations between PASI score and biochemical parameters were analyzed using Spearman’s rank correlation coefficient.

Results: The mean PASI score was 8.38 ± 6.63, indicating predominantly mild to moderate disease severity. Serum zinc, copper, and Cu/Zn ratio showed considerable inter-individual variability. Serum copper levels differed significantly across PASI-defined severity groups (p = 0.030), whereas serum zinc levels and Cu/Zn ratio did not show significant variation. Correlation analysis demonstrated no association between PASI score and serum zinc (rₛ = +0.03), while weak negative correlations were observed between PASI score and serum copper (rₛ = −0.31) and Cu/Zn ratio (rₛ = −0.21).

Conclusion: The study highlights altered trace-element homeostasis in psoriasis, with serum copper levels showing significant variation across disease severity categories. However, serum zinc levels and Cu/Zn ratio did not demonstrate a significant correlation with PASI score, suggesting limited utility as markers of disease severity. Further large-scale longitudinal studies incorporating dietary assessment and inflammatory biomarkers are needed to better elucidate the role of trace elements in psoriasis.