Mortality of combined serum phosphorus and parathyroid hormone concentrations and their changes over time in hemodialysis patients

Background: Mineral and bone disorder (MBD) is common and associated with mortality in patients with chronic kidney disease (CKD) Given that disarrays in serum phosphorus (P) and parathyroid hormone (PTH) levels and their changes over time are closely interrelated, modeling mortality-predictability of their combinations may help improve CKD patient management.

Methods: A historical cohort study was undertaken to evaluate the joint effect of serum P and PTH levels on mortality in 107,299 chronic hemodialysis (HD) patients. Changes in serum P and PTH levels over 6months, in particular discordant changes, were also modeled with mortality.

Results: HD patients were 64±15 (mean±SD)years old and included 45% women, 33% African-American, and 59% diabetic. Compared with serum P level ≥7.0mg/dL and PTH level ≥600pg/mL, adjusted hazard ratio (HR) tended to be lowest in patients with serum P level of 3.5-<5.5mg/dL combined with PTH level of 150-<300pg/mL (HR 0.64, 95% confidence interval 0.61-0.67). A change over time in serum P level towards the 3.5-<5.5mg/dL range from higher or lower ranges was associated with a decreased mortality, whereas only change in PTH level from <150pg/mL to 150-<300pg/mL range was associated with a lower risk of mortality. Upon discordant changes of PTH and P, i.e., decrease in one of the two measures while the other increased, no change in mortality risk was observed.

Conclusion: In CKD-MBD management, patent survival is the greatest with controlling both serum P and PTH levels in balance. Tailoring an individualized treatment strategy in CKD-MBD may benefit patients. Further studies are needed.