Proportions of hyperphosphatemia in different stages of chronic kidney disease

Introduction: In chronic kidney disease (CKD) patients, calcium and phosphate homeostasis disorders occur. Decreased kidney function will result in decreased phosphate excretion. In stage 3b CKD, the kidneys are no longer able to compensate for the phosphate load sufficiently and hyperphosphatemia is resulted. Objectives: This research aimed to figure out the proportions of hyperphosphatemic patients at different levels of glomerular filtration rate in CKD. Patients and Methods: An observational study with a cross-sectional approach involving 80 CKD subjects, distributed into stage 3 (n = 20), stage 4 (n = 20), stage 5 non-dialysis (n = 20) and stage 5 dialysis CKD subjects(n = 20), at Wahidin Sudirohusodo hospital and Unhas hospital, Makassar, from April through August 2021. Phosphate concentrations were measured using ELISA (enzyme-linked immunosorbent assay) kit (Immutopics). A result of the statistical test would be significant if P < 0.05. Results: The average phosphate concentrations at stage 3, stage 4, stage 5 non-dialysis and stage 5 dialysis were 4.14 ± 1.85 mg/dL, 4.17 ± 1.12 mg/dL, 6.43 ± 3.09 md/dL and 5.42 ± 3.09 mg/dL, respectively. Based on the avergae phosphate concentration by CKD stage, stage 3 was not significantly different from stage 4 (P = 0.969), however there was a significant difference between stage 3 and stage 5 non-dialysis (P = 0.004) and also between stage 4 and stage 5 non-dialysis (P = 0.005). The proportions of hyperphosphatemic patients (serum phosphate >4.5 mg/dL) with stage 3, stage 4, stage 5 non-dialysis and stage 5 dialysis CKD were 15% (n = 3), 20% (n = 4), 75% (n = 15) and 43.3% (n = 9), respectively. Conclusion: The porportion of hyperphosphatemic subjects increased with the decline in the kidney function. Dialysis process reduces phosphate levels and the proportion of patients with hyperphosphatemia.