Reference Range of Serum Zinc Concentration in Patients with Heart Failure: A Systematic Review and Meta-analysis of Cross-Sectional Studies in the 21st Century

Background: Heart failure (HF) is a clinical disorder and Zinc is an important cofactor in regulating oxidative status. The present study aimed to determine the mean concentration of serum zinc in patients with HF. Methods: PubMed, Embase, Scopus, and Web of Science were used in the present systematic review and meta-analysis to find relevant cross-sectional studies up to 1st January 2020. A randomeffects model was used to pool the effect size (ES) and 95% confidence intervals (CI). In addition, meta-regression analysis was performed to find the sources of statistical heterogeneity among the studies. Results: Our meta-analysis of 1358 HF patients indicated that their mean serum zinc concentration was 66.24 μg/dl (95% CI: 59.16, 73.33). In sub-analysis, the mean concentration was 75.04 μg/dl and 52.90 μg/dl in patients 65 years and 65 years old, respectively. Subgroup analysis by geographical region showed that mean serum zinc was 70.70 μg/dl, 69.08 μg/dl and 60.91 μg/ dl in HF patients from Europe, America, and Asia, respectively. Meta-regression analysis indicated a reduction of 1.42 μg/dl in serum zinc per each year of aging. Conclusion: In summary, our meta-analysis indicates that serum zinc concentrations have a narrow range in HF patients worldwide that declines with age and varies with geographical region. Additionally, serum zinc concentrations are lower in HF patients, specifically in the elderly.