A team led by Michel Vallée, MD, PhD, of Maisonneuve-Rosemont Hospital, University of Montreal, studied a retrospective cohort of 45 chronic HD patients with SHPT who were switched from oral alfacaclidol—which requires 25-hydoxylation in the liver to be effective—to oral calcitriol—the fully hydoxylated active form of vitamin D3.
Results showed that the mean dose of active vitamin D decreased from 3.50 mcg per week at baseline to 2.86 mcg after the switch, Dr Vallée and colleagues reported in a paper published online ahead of print in International Urology and Nephrology. The mean parathyroid hormone (PTH) level decreased significantly from 94.4 to 82.6 pmol/L and the mean corrected serum calcium increased from 2.17 to 2.25 mmol/L.
Bypassing hepatic 25-hydroxylation appears to be associated with greater efficacy of calcitriol at increasing serum calcium and inhibiting PTH secretion, the investigators concluded. “These observations must be taken into consideration before choosing a vitamin D3 or switching from one to another,” they wrote. “In light of these results, calcitriol may be the treatment of choice for SHPT in chronic hemodialysis patients, especially for those with resistant hyperparathyroidism, which does not respond adequately to alfacalcidol.”
Alfacalcidol remains a valid option for some pre-dialysis patients who have mild SHPT easily controlled with alfacalcidol, they added.
1. Rauscher S, Lafrance JP, Pichette V, et al. Conversion of oral alfacalcidol to oral calcitriol in the treatment of secondary hyperparathyroidism in chronic hemodialysis patients. Int Urol Nephrol 2016; published online ahead of print.