Serum Zinc Levels in Chronic Kidney Disease Patients, Hemodialysis Patients, and Healthy Controls: Systematic Review and Meta-Analysis

Objectives Patients with chronic kidney disease (CKD) are susceptible to changes in zinc homeostasis through anorexia and dietary restrictions, as well as hemodialysis (HD). Changes in zinc homeostasis might predispose CKD and HD patients to specific adverse effects, including erythropoietin-resistant anemia, oxidative stress, atherosclerosis, and cardiovascular disease. Because serum zinc levels are rarely measured in CKD and HD patients, zinc supplementations do not represent a routine therapy for CKD and dialysis patients. Therefore, in this meta-analysis, we aimed to assess serum zinc levels in CKD and HD patients compared with healthy controls (HC). In addition, we investigated whether HD affects serum zinc levels by comparing serum zinc levels in HD versus CKD patients and comparing serum zinc pre- versus post-HD. Design and Methods A comprehensive search of databases was conducted to identify either observational studies or randomized trials that assessed serum zinc levels in either CKD and/or HD patients in comparison to HC. We conducted a random-effects meta-analysis. Results Our meta-analysis included 42 studies with a total of 4,161 participants, of whom 460 were CKD patients, 2,047 were HD patients, and 1,654 were HCs. Both CKD and HD patients showed lower serum zinc levels compared with HC (mean difference = −22.86 μg/dL, 95% CI −33.25 to −12.46; mean difference = −13.64 μg/dL, 95% CI −21.47 to −53.80, respectively). CKD and HD patients showed no significant difference in serum zinc levels (mean difference = 15.39, 95% CI −8.91 to 39.68). Pre-HD serum zinc levels were significantly lower than those post-HD (mean difference = −7.51 μg/dL, 95% CI −14.24 to −0.78). Conclusion In the current study, the serum zinc levels were lower in CKD and HD patients compared to HCs and appears to be more common than reported in daily clinical practice. It may be beneficial to assess serum zinc levels in CKD and HD patients. More research on zinc in kidney disease is encouraged. Patients with chronic kidney disease (CKD) are susceptible to changes in zinc homeostasis through anorexia and dietary restrictions, as well as hemodialysis (HD). Changes in zinc homeostasis might predispose CKD and HD patients to specific adverse effects, including erythropoietin-resistant anemia, oxidative stress, atherosclerosis, and cardiovascular disease. Because serum zinc levels are rarely measured in CKD and HD patients, zinc supplementations do not represent a routine therapy for CKD and dialysis patients. Therefore, in this meta-analysis, we aimed to assess serum zinc levels in CKD and HD patients compared with healthy controls (HC). In addition, we investigated whether HD affects serum zinc levels by comparing serum zinc levels in HD versus CKD patients and comparing serum zinc pre- versus post-HD. A comprehensive search of databases was conducted to identify either observational studies or randomized trials that assessed serum zinc levels in either CKD and/or HD patients in comparison to HC. We conducted a random-effects meta-analysis. Our meta-analysis included 42 studies with a total of 4,161 participants, of whom 460 were CKD patients, 2,047 were HD patients, and 1,654 were HCs. Both CKD and HD patients showed lower serum zinc levels compared with HC (mean difference = −22.86 μg/dL, 95% CI −33.25 to −12.46; mean difference = −13.64 μg/dL, 95% CI −21.47 to −53.80, respectively). CKD and HD patients showed no significant difference in serum zinc levels (mean difference = 15.39, 95% CI −8.91 to 39.68). Pre-HD serum zinc levels were significantly lower than those post-HD (mean difference = −7.51 μg/dL, 95% CI −14.24 to −0.78). In the current study, the serum zinc levels were lower in CKD and HD patients compared to HCs and appears to be more common than reported in daily clinical practice. It may be beneficial to assess serum zinc levels in CKD and HD patients. More research on zinc in kidney disease is encouraged.