Correlation between anemia and phosphorus metabolism in patients with nondialysis chronic kidney disease

This study investigated the correlation between anemia and phosphorus metabolism in patients with nondialysis chronic kidney disease (CKD). A total of 196 patients with nondialysis CKD with complete clinical information who were hospitalized in the Department of Nephrology at the Sixth Affiliated Hospital of Kunming Medical University from November 2021 to June 2022 were enrolled. Among these patients, 119 had anemia (anemia group), and 77 did not have anemia (nonanemia group). Univariate logistic regression analysis was performed to analyze the effects of diabetes mellitus (DM), hypertension, and the levels of serum phosphorus, blood calcium, high-sensitivity C-reactive protein (Hs-CRP), and 24-h urinary electrolytes on anemia. Multivariate logistic regression analysis using backward stepwise selection was then performed to further analyze the effect of each factor on anemia. DM, hypertension, the levels of corrected calcium, serum phosphorus, intact parathyroid hormone (iPTH), Hs-CRP, and 24-h urinary phosphorus, and the fractional excretion of phosphorus (FePi) (all P < 0.05) were correlated with the incidence of anemia in patients with CKD. Furthermore, there was a 5.82-fold increase, 0.12-fold decrease, and 0.04-fold increase in the risk of anemia for every 1-mmol/L increase in serum phosphorus (OR = 6.82, 95% CI: 1.32–35.11), 1-mmol/L increase in 24-h urinary phosphorus (OR = 0.88, 95% CI: 0.81–0.91), and 1-mg/dL increase in Hs-CRP (OR = 1.04, 95% CI: 1.01–1.07), respectively. The FePi and serum phosphorus and Hs-CRP levels were independent risk factors, and the 24-h urinary phosphorus level was an independent protective factor for anemia in patients with nondialysis CKD.