Randomised controlled trials that compared oral with intravenous administration of intermittent calcitriol in patients with secondary hyperparathyroidism (according to established diagnostic criteria), were eligible for inclusion. Secondary hyperparathyroidism diagnosis was defined as patients in which baseline parathyroid hormone was at least three times above the normal range. Eligible trials also had to report data on parathyroid hormone before and after the intervention. Trials in which patients were receiving peritoneal dialysis were excluded, as were those in which patients received other vitamin D drugs or medications which may interfere with vitamin D and/or bone homeostasis.
Outcomes of interest were intact parathyroid hormone, serum alkaline phosphatase, serum total calcium, serum phosphorus, incidence of hypercalcaemia, incidence of hyperphosphatemia, calcitriol-related death, and other adverse events.
In included trials, the mean age of participants ranged from 40 to 58 years and their baseline parathyroid hormone values ranged from 310 to 1979pg/mL. Calcitriol dose ranged from 2.0 to 6.1μg/week; doses were similar for intravenous and oral modes of administration. Trial duration ranged from 10 to 24 weeks.
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.