Altered Metabolism of Blood Manganese Is Associated with Low Levels of Hemoglobin in Patients with Chronic Kidney Disease

Blood manganese (Mn) level has been reported to be higher in patients with anemia or iron deficiency. The purpose of this study was to analyze the relationship between blood Mn level and anemia in patients with chronic kidney disease (CKD). A total of 334 patients with CKD who were not treated with dialysis were included in this study. Blood Mn level and serum markers regarding anemia, renal function, and nutrition were measured and analyzed. Median blood Mn level was 8.30 (interquartile range(IQR): 5.27–11.63) µg/L. Univariate linear regression showed that blood Mn level was correlated with age (β = −0.049, p < 0.001), smoking (β = −1.588, p = 0.009), hypertension (β = −1.470, p = 0.006), serum total iron-binding capacity (TIBC) (β = 0.025, p < 0.001), serum transferrin (β = 0.029, p < 0.001), and estimated glomerular filtration rate (eGFR; β = 0.036, p < 0.001). Results of multiple linear regression analysis showed that beta coefficient of hemoglobin was 0.847 (p < 0.001) for blood Mn level in all participants after controlling for covariates, including gender, age, body mass index, smoking, diabetes, hypertension, and eGFR. Multivariate Poisson regression analysis with robust variance after adjusting for gender, age, smoking, hypertension, diabetes, eGFR, and nutritional markers showed that higher blood Mn level (per 1 µg/L increase) was associated with decreased prevalence of anemia (PR 0.974, 95% CI: 0.957 to 0.992, p = 0.005). Taken together, our results demonstrate that blood Mn level is positively associated with hemoglobin level in CKD patients. This might provide important information in the understanding of the pathogenesis of CKD-related anemia.