LAUSR

Active vitamin D analogues are used routinely for the treatment of secondary hyperparathyroidism in children with end-stage renal disease (ESRD) on peritoneal dialysis (PD). Calcitriol is preferred active form of vitamin D, while data on efficacy of alfacalcidol in children on PD are limited. The aim of this study was to compare the efficacy of these two active vitamin D analogues for the treatment of secondary hyperparathyroidism in children on PD. This retrospective cohort study included data from 26 pediatric patients under 18 years of age with ESRD on PD who were treated at the National Research Center for Maternal and Child Health, Astana, Kazakhstan. Patients were allocated by initial treatment into two groups: oral alfacalcidol (n=21) and oral calcitriol (n=5). The first step of the study was to compare the efficacy of treatment between this two groups 3 and 6 months after. The second step was to compare the efficacy of calcitriol in subgroup of patients from alfacalcidol group who were switched to calcitriol later (n=12). The following characteristics were analyzed: parathyroid hormone (PTH), total plasma calcium, ionized plasma calcium, plasma phosphorus, initial dose of active vitamin D and corrected dose of vitamin D after 3 months. Independent t-test and repeated measures Anova were used for comparison between alfacalcidol and calcitriol groups. To compare data in subgroup between baseline and 3 months after conversion from alfacalcidol to calcitriol we used paired Student t-test. The mean age and baseline characteristics were no different between alfacalcidol and calcitriol groups (Table 1). The initial dose of alfacalcidol was 2.42±1.03 µg/week (0.157±0.097 µg/kg/week) and 2.09±0.74 µg/week (0.105±0.039 µg/kg/week) for calcitriol were not significantly different (P=0.5 and P=0.25 respectively). After 3 months of treatment there was statistically significant decrease of PTH level in calcitriol group 180±168 pmol/L comparing to alfacalcidol group 869±670 pmol/L (P=0.006). After 6 months, there was statistically significant decrease of PTH level in calcitriol group 261±259 pmol/L in contrast with alfacalcidol group 1080±716 pmol/L (P=0.047) and rise in total calcium in calcitriol group 2.46±0.17 mmol/L compared with alfacalcidol group 2.09±0.25mmol/L (P=0.035). The mean dose of calcitriol was also significantly lower as opposed to alfacalcidol dose: 0.04±0.039 µg/kg/week and 0.17±0.076 µg/kg/week respectively (P=0.002). The median age of children who were switched from alfacalcidol to calcitriol were significantly younger comparing with those who continued alfacalcidol (5±4.6 and 10±4.3 years of age respectively (P=0.022)). 3 months after conversion there was significant increase in ionized calcium level and decrease in PTH level comparing with baseline (Table 2). The dose of alfacalcidol before and dose of calcitriol after switch were differed (0.18±0.1 µg/kg/week and 0.13±0.05 µg/kg/week respectively, P=0.025) Calcitriol showed superior efficacy for the treatment of secondary hyperparathyroidism in children on PD with the dose 4.25 times lower that of alfacalcidol. Alfacalcidol had limited efficacy for the treatment of secondary hyperparathyroidism in younger children when prescribed in recommended doses.