A decrease in intact parathyroid hormone (iPTH) levels is associated with higher mortality in prevalent hemodialysis patients

Abstract

Background The mortality of dialysis patients is 10- to 100-fold higher than in the general population. Baseline serum PTH levels, and more recently, changes in serum PTH levels (delta;PTH) over time, have been associated to mortality in dialysis patients. Methods We explored the relationship between delta;PTH over 1 year with mortality over the next year in a prospective cohort of 115 prevalent hemodialysis patients from a single center that had median baseline iPTH levels within guideline recommendations. Results Median baseline iPTH levels were 205 (116.5, 400) pg/ml. delta;iPTH between baseline and 1 year was 85.2 ± 57.1 pg/ml. During the second year of follow-up, 27 patients died. delta;iPTH was significantly higher in patients who survived (+157.30 ± 25.82 pg/ml) than in those who died (+39.03 ± 60.95 pg/ml), while baseline iPTH values were not significantly different. The highest mortality (48%) was observed in patients with a decrease in ÄiPTH (ÄiPTH quartile 1, negative delta;iPTH) and the lowest (12%) mortality in quartile 3 delta;iPTH (delta;iPTH increase 101-300 pg/ml). In a logistic regression model, delta;iPTH was associated with mortality with an odds ratio (OR) of 0.998 (95% CI 0.996-0999, p = 0.038). In multivariable analysis, mortality risk was 73% and 88% lower for patients with delta;iPTH 0-100 pg/ml and 101-300 pg/ml, respectively, than for those with a decrease in delta;iPTH. In patients with a decrease in delta;iPTH, the OR for death was 4.131 (1.515-11.27)(p = 0.006). Conclusions In prevalent hemodialysis patients with median baseline iPTH values within the guideline recommended range, a decrease in ÄiPTH was associated with higher mortality. Further studies are required to understand the mechanisms and therapeutic implications of this observation that challenges current clinical practice.