Impact of elevated intact parathyroid hormone on mortality and renal disease progression in patients with chronic kidney disease stages 3 and 4.

Objective: To estimate the impact of elevated intact parathyroid hormone levels on time to death and renal replacement therapy in patients with chronic kidney disease stages 3 and 4.

Methods: A retrospective cohort analysis from 01/1996 to 09/2007 was conducted in 11,092 patients with chronic kidney disease stages 3 and 4 patients using Cockroft-Gault and Modification of Diet in Renal Disease equations to estimate their glomerular filtration rates. Patients' highest parathyroid hormone levels were used to define the index date and cohort (followed for 1 year). Mortality and renal replacement therapy events were evaluated among cohorts at pre-defined parathyroid hormone levels.

Results: As the intact parathyroid hormone levels increased, the mean age, number of females and estimated glomerular filtration rates decreased. Patients with an intact parathyroid hormone level<50 pg/mL were defined as the reference group. Similar results were found using the Modification of Diet in Renal Disease equation for calculating estimated glomerular filtration rate, which was possible in 48% of the patients where race could be identified. Combined mortality and renal replacement therapy adjusted hazard ratio using Cox regression for intact parathyroid hormone level 51-110 pg/mL was 1.12 (0.82-1.54), intact parathyroid hormone level 111-199 pg/mL was 2.42 (1.78-3.29), intact parathyroid hormone level 200-299 pg/mL was 3.01 (2.14-4.27), intact parathyroid hormone level 300-399 pg/mL was 3.12 (2.09-4.60), intact parathyroid hormone level 400-499 pg/mL was 3.91 (2.61-5.85) and intact parathyroid hormone level>500 pg/mL was 2.67 (1.84-3.84).

Conclusion: Intact parathyroid hormone levels>50 pg/mL in patients with chronic kidney disease stages 3 and 4 are associated with an escalating combined risk of death or RRT.