Frequency of Serum Calcium Imbalance in Chronic Kidney Disease Patients

Abstract

Chronic kidney disease (CKD) is frequently accompanied by disturbances in mineral metabolism, particularly abnormalities in serum calcium homeostasis. Calcium imbalance, including hypocalcemia and hypercalcemia, contributes to chronic kidney disease-mineral and bone disorder and may worsen skeletal and cardiovascular outcomes. Local evidence regarding the burden of serum calcium imbalance in Pakistani CKD patients remains limited. Objective: To determine the frequency of serum calcium imbalance in patients with chronic kidney disease and to evaluate its association with CKD stage and selected biochemical and clinical variables. Methods: This cross-sectional study was conducted in the Department of Chemical Pathology in collaboration with the Kidney Center, Quaid-e-Azam Medical College/B.V. Hospital, Bahawalpur, Pakistan, over six months from 19 February 2025 to 19 August 2025. A total of 97 patients aged 18–60 years with CKD stages I–IV were enrolled through non-probability consecutive sampling. Patients with CKD stage V, dialysis-dependent disease, acute kidney injury, or conditions and medications affecting calcium metabolism were excluded. Demographic and clinical data were recorded, and laboratory investigations included serum calcium, phosphate, albumin, renal function tests, and estimated glomerular filtration rate (eGFR). Corrected calcium was calculated in patients with hypoalbuminemia. Data were analyzed using SPSS version 26. Associations were assessed using the chi-square test, with p<0.05 considered statistically significant. Results: The mean age of participants was 44.18 ± 10.27 years, and 55.7% were male. Overall, 52 of 97 patients (53.6%) had serum calcium imbalance. Hypocalcemia was observed in 41 patients (42.3%), whereas hypercalcemia was found in 11 patients (11.3%). The frequency of calcium imbalance increased progressively with worsening CKD stage, from 22.2% in stage I to 66.7% in stage IV. Serum calcium imbalance was significantly associated with elevated serum phosphate levels (p=0.003) and advanced CKD stage (p=0.009). Patients with calcium imbalance also had lower mean eGFR and serum albumin levels than those of normocalcemic patients. Conclusion: Serum calcium imbalance was highly prevalent in non-dialysis CKD patients, with hypocalcemia as the predominant abnormality. Advanced CKD stage and hyperphosphatemia were significant correlates, supporting the need for routine surveillance of mineral metabolism in CKD patients to enable earlier intervention and reduce CKD-related complications.