The efficacy and safety of zinc gluconate supplementation on quality of life, sleep quality, and serum albumin in hemodialysis patients: A randomized clinical trial
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Chronic kidney disease (CKD) is a condition where the removal of waste products, hemostasis of electrolytes, activation of vitamin D, and regulation of blood pressure are impaired. To compensate impaired renal function, waste products and excess water are removed from the blood through dialysis, including hemodialysis and peritoneal dialysis. Although hemodialysis mimics some functions of the kidney, it is not as effective as normal kidney. Indeed, patients on hemodialysis suffer from several problems, including decreased level of albumin, poor sleep quality, and low quality of life. Hemodialysis patients usually have less albumin than healthy individuals due to increased albumin excretion during hemodialysis. Also, synthesis of albumin is decreased in response to high inflammation and malnutrition among hemodialysis patients. Moreover, malnutrition is a cause of albumin synthesis reduction. Studies showed that some nutrients, such as zinc, may have favorable effect on albumin level, for instance, zinc supplementation resulted in increment of albumin in sever zinc deficient subjects. Poor sleep quality is another problem among hemodialysis patients. Another common problem in hemodialysis patients is low quality of life, which tends to be lower than healthy counterparts. Evidence confirm that zinc deficiency is prevalent among hemodialysis patients. Although zinc supplementation could putatively improve albumin level, sleep quality, and quality of life in previous studies, there is limited evidence regarding hemodialysis patients. Additionally, most previous studies used zinc supplement in the form of zinc sulfate, whilst the effect of zinc gluconate, a more digestible with less side effects form of zinc supplement, has not been examined.
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In this parallel randomized clinical trial, 87 hemodialysis patients were randomly assigned in the zinc (n=44) or placebo group (n=43) for 12 weeks. Patients in the zinc group received one 30 mg zinc gluconate tablet per day. Quality of life was assessed The Kidney Disease Quality of Life (KDQOL) instrument, and sleep quality was evaluated by The Pittsburgh Sleep Questionnaire. Also, serum concentrations of albumin and high sensitivity C-reactive protein (hs-CRP) were measured at baseline and end of the study. This study was a parallel double-blind randomized clinical trial that lasted 12 weeks. The intervention was conducted in Isfahan, Iran from October 2020 to October 2021. We used following equation to estimate required sample size: n = 2 [(Z1-α / 2 + Z1-β) 2 × S2] / Δ2. In this equation, α=0.05, and β=0.20 (the power of the study was 80%). The required sample size was 36 subjects in each group. To overcome the possibility of subject withdrawal, we enrolled 80 subjects (n=40 in each group). Subjects in the intervention group were prescribed one 30 mg zinc gluconate tablet per day, produced by Dineh Company, Tehran, Iran, for 12 weeks. In the placebo group, tablets contained 30 mg starch, where its color, appearance, smell, and taste were similar to the zinc gluconate, and were administered to the patients.A questionnaire including demographic information, medical history, and medications was completed for each subjects.The Pittsburgh Sleep Questionnaire was used to assess sleep quality. Albumin was measured by bromocresol green method, in which serum albumin formed as a green-blue color complex. The amount of colored products was an indicator of albumin level. Imuno turbid method (Audit kit, Delta treatment, Ireland-Iran) was applied to measure high sensitivity C-reactive protein (hs-CRP).The Kidney Disease Quality of Life Instrument (KDQOL) was used to measure the health-related quality of life. During the intervention, hemodialysis patients were asked to complete two 3-day food records (two non-dialysis days and one dialysis day). Q-Q diagrams and the Kolmogrov-Smirnov test were used to check the normality of quantitative variables. A chi-square test was used to compare the distribution of qualitative variables between the two groups.In conclusion, zinc supplementation elicited improvements in sleep quality and ameliorated albumin reduction in hemodialysis patients. We observed no adverse effect from zinc supplementation in these patients Accordingly, it appears that malnutrition and poor sleep quality may be improved by zinc supplementation.