Essential Trace Element Status in Systemic Lupus Erythematosus: a Meta-analysis Based on Case-Control Studies.

The homeostasis of trace elements is essential to regulate different aspects of the immune system and might play important roles in systemic lupus erythematosus (SLE). However, epidemiological evidences that compared the level of essential trace elements in SLE patients and healthy controls (HCs) did not reach a consensus. This was the first meta-analysis to comprehensively assess the level of zinc (Zn), copper (Cu), iron (Fe), and selenium (Se) in SLE and HCs. PubMed, Embase, and Web of Science were systematically searched until April 2022 to find relevant literatures. The PRISMA statement 2020 was followed to make sure the quality of reporting a meta-analysis. The outcomes were assessed by pooled standardized mean difference (SMD) and 95% confidence intervals (CIs). Finally, eleven articles with 1262 subjects were included in the meta-analysis. Significantly lower levels of Zn (SMD = -0.709; 95% CI: -1.173, -0.245; P = 0.003) and Fe (SMD = -1.783; 95% CI: -2.756, -0.809; P = 0.000) were found in SLE compared with HCs. Higher levels of Cu (SMD = 0.808; 95% CI: 0.234, 1.382; P = 0.006) were found in SLE patients. In addition, compared with HCs, Fe and Zn were lower in SLE patients in Asia and Cu was higher in SLE patients in Europe. However, no significant difference was observed in the level of Se (SMD = -0.251; 95% CI: -1.087, 0.586; P = 0.557). Above all, SLE patients exhibited lower Zn and Fe and increased Cu concentrations compared with HCs. Further studies are warranted to investigate the mechanism of Zn, Cu, and Fe in SLE patients.