Efficacy of Zinc Acetate in the Treatment of Zinc Deficiency in Elderly Inpatients and Effect of Total Dose on Its Replacement Therapy.

We aimed to determine the efficacy of zinc acetate hydrate (ZAH) treatment for hypozincemia in elderly inpatients and to identify the factors affecting its therapeutic effect. We enrolled 79 patients with a mean age of 82 years. The mean serum zinc level before ZAH administration was 53.4 ± 11.5 µg/dL. More than half of the patients (67%) had zinc deficiency (<60 µg/dL), whereas 33% had subclinical zinc deficiency (60-80 µg/dL). The median increase in serum zinc level per ZAH tablet (25 mg) was 1.00 µg/dL. Based on the cutoff value, two groups were identified: slight increase (<1.00 µg/dL) and marked increase (≥1.00 µg/dL) groups; the difference between the two groups was significant (0.57 ± 0.22 µg/dL, n = 39 vs. 1.68 ± 0.70 µg /dL, n = 40; p < 0.0001, Wilcoxon rank sum test). Logistic regression analysis using total zinc dose, serum albumin level, impaired renal function, and diuretics as multivariate variables revealed a significant difference in total zinc dose (total number of tablets per 25 mg tablet: odds ratio 1.056, 95% confidence interval 1.019-1.095, p = 0.003). A significant increase in serum zinc levels was observed in the group with a total zinc dose of less than 1000 mg. The results suggest that an increasing trend in total zinc dose is associated with a low increase in serum zinc levels. Therefore, for the treatment of zinc deficiency in elderly inpatients, serum zinc levels need to be measured once, at a total dose of 1000 mg after initiation of ZAH.