Prevalence and risk factors for hypercalcemia among non-dialysis patients with chronic kidney disease-mineral and bone disorder

Purpose To examine the prevalence and risk factors for hypercalcemia among non-dialysis chronic kidney disease (CKD) patients with mineral and bone disorder (MBD). Methods A retrospective cohort study was conducted in Singapore General Hospital, involving all CKD stage 4 and 5 pre-dialysis patients who were on treatment for MBD in June 2016. Each patient was followed up for 1 year and screened for hypercalcemia episodes.Mild, moderate and severe hypercalcemia were defined as corrected calcium of 2.47-3.00, 3.01-3.50 and 3.51mmol/l respectively. Patients who were on dialysis, post-renal transplant, post-parathyroidectomy or had no calcium levels taken during the study period were excluded. Details related to patients' clinical information and hypercalcemia episodes were collected. Multivariate logistic regression analysis was performed to evaluate risk factors for hypercalcemia. Results Of 557 patients, 75 (13.4%) patients developed hypercalcemia. There were 120 (97.6%) mild and 3 (2.4%) moderate hypercalcemia episodes. The daily elemental calcium intake from phosphate binders and usage of vitamin D analogues did not differ between patients with and without hypercalcemia (p>0.05). After adjusting for covariates, lower baseline iPTH level [odds ratio (OR) 0.96, 95% CI 0.93-0.99], history of hypercalcemia in past 1year (OR 11.11, 95% CI 3.36-36.75) and immobility (OR 3.34, 95% CI 1.34-8.40) were associated with increased hypercalcemia risk. Conclusion Hypercalcemia affects a significant proportion of pre-dialysis patients with MBD. More studies should be undertaken to evaluate other risk factors associated with hypercalcemia.