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.