Paricalcitol therapy for secondary hyperparathyroidism in patients on maintenance hemodialysis previously treated with calcitriol: A single-center crossover study

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease. The medical management of SHPT in hemodialysis (HD) patients commonly utilizes intravenously administered vitamin D, either calcitriol or newer analogs (paricalcitol or doxercalciferol). Recent published reports have suggested that the use of paricalcitol in HD patients offers a morbidity or mortality advantage in comparison to treatment with calcitriol. The objective of this study was to compare the biochemical markers of SHPT during serial treatment with calcitriol and paricalcitol. We converted all HD patients in our large urban dialysis center from calcitriol to paricalcitol using a 1:3 conversion ratio, based on published data. Demographic, clinical, and laboratory data were collected, and comparisons of individual patient mean values were made after adjusting for equivalent doses. In addition, we recorded the number of missed doses during 6 months of therapy with calcitriol and with paricalcitol. Seventy-three patients were treated with calcitriol for at least 6 months before conversion to paricalcitol, and then completed 6 months of treatment with paricalcitol. Converting from calcitriol to paricalcitol resulted in lower serum calcium (P=0.048), lower calcium-phosphorus product (P=0.014), reduced biointact parathyroid hormone (P=0.029), and reduced serum alkaline phosphatase (P=0.0002). Most dramatically, there was a highly significant difference in the number of missed doses (P<0.0001). This study, the first comparing long-term calcitriol to paricalcitol treatment in the same HD patients, offers several important clues that may explain outcome differences reported in large pooled reports.