Objectives

Chronic kidney disease (CKD) patients are liable 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. Since 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.

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 4161 participants, of whom 460 represented CKD patients, whereas 2047 patients represented HD patients. 1654 participants were healthy controls. Both CKD and HD patients showed lower serum zinc levels compared with HC (mean difference = -22.86 μg/dl, 95% CI [-33.25, -12.46]; mean difference = -13.64 μg/dl, 95% CI [-21.47, -53.80], respectively). CKD and HD patients showed no significant difference in serum zinc levels (mean difference = 15.39, 95% CI [-8.91, 39.68]). Pre-HD serum zinc levels were significantly lower than those post-HD (mean difference = -7.51 μg/dl, 95% CI [-14.24, -0.78]).

Conclusion

Occurrence of Lower serum zinc levels in CKD and HD patients than in HC appears to be more frequent than reported in daily clinical practice. An increase in the frequency of zinc measurement might be beneficial.