Effects of Serum Calcium and Phosphorus on Anemia Development in Patients with Stage 3b and 4 Chronic Kidney Disease.

Objective: The relationship between anemia and bone disease markers was examined to a great extent in patients undergoing renal replacement therapy. The aim of this study was to investigate the relationship between bone disease markers and anemia in a cohort of adult patients without renal replacement therapy. Materials and Methods: A total of 1279 patients with stage 3b and 4 kidney disease who were admitted to the Nephrology outpatient clinic of the Kayseri Research and Training Hospital between January 1, 2014, and December 31, 2017, formed the study cohort. Logistic and linear regression models were developed to explore the adjusted effects of calcium, phosphorus, parathyroid hormone (PTH), and 25-hydroxyvitamin D concentrations on anemia. Other confounding variables were included in regression equations. Results: In the adjusted logistic regression model, it was found that the prevalence of anemia was significantly associated with calcium, phosphorus, and PTH levels. An increase of 1 mmol L^-1 in serum calcium and phosphorus concentrations was associated with a 32% reduction (OR: 0.68; 95% CI: 0.51-0.91; p=0.011) and a 2.4-fold increase (OR: 2.40; 95% CI: 1.40, 4.13; p=0.002) in the prevalence of anemia, respectively. In a receiver operating characteristic analysis for identifying anemia, discriminating power of phosphorus was superior to the other bone disease markers [best cut-off value >1.23 mmol L^-1, AUC 0.65 (0.624-0.677)] Conclusion: Serum calcium and phosphorus levels may contribute to the development of anemia in patients with stage 3b and 4 chronic kidney disease who are not receiving renal replacement therapy. [ABSTRACT FROM AUTHOR]