Efficacy of hyperphosphatemia control in the progression of chronic renal failure and the prevalence of cardiovascular calcification

Background and aims: Chronic kidney disease mineral- and bone disorder (CKD-MBD) has been studied more often in dialysis than in predialysis CKD patients. The association between efficacy of hyperphosphatemia control and chronic renal failure (CRF) progression, prevalence of bone disease and cardiovascular calcification was the objective of the present investigation. Material and methods: 42 patients with CKD in Stage 5, regularly monitored for 5 years, were divided into Group 1 of 20 patients with normal serum phosphate (sPO(4)) levels and Group 2 of 22 patients with hyperphosphatemia registered at the majority of checks. Serum urea, creatinine, calcium (sCa) and sPO(4) levels were regularly determined in the retrospective 5-year period. At the end of this period iPTH, bone alkaline phosphatase-BAP and inflammation markers (CRP, fetuin-A) were measured, valvular and arterial calcifications were detected by B mode echocardiogram and soft-tissue native radiograms of the pelvis and the wrist. Results: Progression of CRF (1/sCr over time) was faster in Group 2 than in Group 1 (b = -0.0577 vs. -0.0288, p = 0.003) during the study period. Average BAP and iPTH values were similar in both groups and 23/42 patients had PTH > 300 pg/ml. Arterial and valvular calcifications were found in 5/23 patients from Group 1 and 14/22 patients from Group 2 (p = 0.011). Linear regression analysis revealed sPO(4) as a predictor for total calcification number, inflammatory diseases as a predictor for valvular calcifications, while sPO(4) and iPTH were predictors for arterial calcifications. Conclusions: More than half the patients with Stage 5 CKD not yet on dialysis exhibited elevated PTH. Faster CRF progression and frequent arterial and valvular calcifications were seen in patients with poor phosphate control and sPO(4) was selected as an independent predictor of total calcification score.