Calcium and phosphorus imbalances as biochemical markers in chronic kidney disease: a case-control study

Background. Chronic kidney disease (CKD) is characterized by progressive deterioration of renal function and is commonly associated with biochemical abnormalities, particularly in calcium and phosphate metabolism. These disturbances play a key role in the pathophysiology of secondary hyperparathyroidism, vascular calcification, and bone mineral disorders. This study purposed to investigate serum calcium and phosphorus profiles in patients with CKD undergoing hemodialysis, evaluate their correlation with renal function indicators, and compare the findings with those of healthy individuals to assess their diagnostic and prognostic relevance. Materials and methods. A comparative cross-sectional study was conducted involving 60 patients with end-stage renal disease (aged 25–72 years; 66.7 % male) undergoing long-term hemodialysis at Al-Hussain Hospital between December 2024 and June 2025, and 30 age- and sex-matched healthy controls. Serum levels of urea, creatinine, calcium, and phosphorus were analyzed using standard biochemical methods. Statistical analysis was performed using SPSS v26, with significance set at p < 0.05. Pearson’s correlation was used to assess relationships between parameters. Results. CKD patients exhibited significantly elevated levels of serum phosphorus (5.37 ± 0.47 mg/dL) and creatinine (7.46 ± 1.15 mg/dL), along with reduced calcium (5.54 ± 0.41 mg/dL) compared to healthy controls (phosphorus: 3.34 ± 0.14 mg/dL, calcium: 9.34 ± 0.14 mg/dL, p < 0.0001 for all). A moderate positive correlation was observed between creatinine and phosphorus (r = 0.54), while calcium levels negatively correlated with phosphorus (r = –0.30). Conclusions. Hyperphosphatemia and hypocalcemia are highly prevalent in patients with advanced CKD and are strongly associated with impaired renal function. The moderate correlation between phosphorus and creatinine suggests that phosphorus levels may serve as a surrogate marker for renal deterioration. Routine monitoring of calcium and phosphorus, alongside conventional markers, is vital for early detection of mineral metabolism disturbances and timely management of CKD-related complications.