Serum Phosphate as an Additional Marker for Initiating Hemodialysis in Patients with Advanced Chronic Kidney Disease

Abstract

 Chronic kidney disease (CKD) is characterized by a gradual and irreversible decline in the kidney function. When an adult's glomerular filtration rate (GFR) falls to 60 ml/min/1.73 m² or below, it indicates a loss of at least half of the normal kidney function. Phosphorus, an essential intracellular anion, is the predominantly stored in bones and soft tissues, with serum phosphorus representing less than 1% of the total body phosphorus content. However, serum phosphorus serves as an indicator of the total body phosphate levels. A significant decline in GFR hampers renal phosphate excretion and disrupts hormonal regulation, often the resulting in phosphate retention and hyperphosphatemia in advanced CKD patients. Prior studies have shown that the CKD patients with severe hyperphosphatemia, especially those delaying renal replacement therapy (RRT), experienced higher phosphate retention. This study aimed to assess the role of serum phosphate in advanced CKD and explore hyperphosphatemia's potential as a marker for guiding the initiation of RRT. Conducted over 18 months on 60 advanced CKD patients at Kempegowda Institute of Medical Sciences, serum phosphate levels were measured, and patients were monitored for dialysis needs over six months. Data analysis was performed using SPSS (Version 26.0) with a significance level of 5% (α = 0.05). Among the patients (mean age: 58.4), 66.7% were male, and 81.7% required hemodialysis. The mean serum phosphate level was higher in patients needing dialysis (7.64 vs. 5.05, P < 0.001), with a serum phosphate threshold of 6.10 predictive of dialysis (sensitivity: 98%). These findings suggest hyperphosphatemia may help determine the timing of dialysis initiation in advanced CKD patients.