Abstract
Background/Objectives: Phosphate level is a critical factor in the health of dialysis patients, as it is linked to cardiovascular risk. In peritoneal dialysis (PD), phosphate removal is related to residual kidney function, dietary intervention, and the ability of the visceral peritoneum to transport phosphate. The role of dialysis prescriptions in phosphate management is not sufficiently enhanced. Standardizing a phosphate removal propensity marker could optimize the peritoneal dialytic program. Our preliminary report aims to evaluate a simple model of phosphate handling and to assess which marker during the peritoneal equilibration test (PET) could better describe the propensity of phosphate removal through the peritoneal membrane. Methods: We hypothesized a simple two-compartment model to describe phosphate removal driven by diffusion. We performed an explorer study on 10 PD patients to assess the reliability of the two-compartment model. In each patient, we evaluated the basal condition and performed a PET with 2 L of 3.86% glucose exchange to assess phosphate handling. We collected blood and peritoneal effluent samples at the beginning of the test (t0), after 1 h (t1), and after 4 h (t4). We proposed and examined the following biomarkers: the ratio between dialysis effluent phosphate and plasma at t4 (PHO-D/P4); the difference between dialysis effluent phosphate at t0 and t4 (PHOΔd0-d4); and phosphate permeability–area product at t4 (PHO-PxA4). Results: 9 men and one woman with a mean age of 58.7 ± 16.7 years and a mean dialysis vintage of 25 ± 18.3 months were enrolled. The PHO-D/P4 mean was 0.68 ± 0.18, the PHO-Δd0-d4 median was 0.89 mmol/L [0.7–1.19], and the PHO-PxA4 mean was 1.7 ± 0.85. PHO-D/P4was significantly related to creatinine D/P4 (beta 1.49, p < 0.001), PHO-Δd0-d4 was significantly influenced by plasma phosphate at t0 (beta 0.56, p < 0.001), and the PHO-PxA4 was significantly influenced by ultrafiltration (beta 0.003, p < 0.001). Conclusions: In our two-compartment model, we observed the independence of the PHO-D/P4marker, which could serve as a potential marker for standardizing phosphate handling. However, PHO-Δd0-d4 and PHO-PxA4 normalized by plasma phosphate at t0 and ultrafiltration rate were able to reserve a potential good performance as markers in phosphate handling standardization.