Active
vitamin D3 is used commonly in
hemodialysis patients with severe
secondary hyperparathyroidism. Intermittent pulse
therapy with active
vitamin D3, either orally or intravenously, has been proven to be effective with less hypercalcemic complication than daily oral
vitamin D3. We therefore designed a three-phase crossover study to compare the effect of oral and intravenous
calcitriol given by intermittent pulse
therapy. Thirteen regular
hemodialysis patients were enrolled. In phase 1, 1 microgram
calcitriol was given orally at bedtime twice a week for 4 months, and then was stopped for 1 month to washout. In phase 2, 1 microgram
calcitriol was given intravenously immediately after
hemodialysis twice a week for 2 months, and then was stopped for 1 month to washout. Phase 3 repeated phase 1 but lasted for only 2 months.
Calcium carbonate was given as the sole
phosphate-binding agent if there was no severe
hypercalcemia or
hyperphosphatemia. Serum
parathyroid hormone (PTH) levels decreased dramatically in all three phase
therapies. As a result, mid-molecule PTH decreased from 5.71 +/- 2.65 to 3.97 +/- 2.92 ng/ml in phase 1 (p = 0.010), from 4.34 +/- 3.39 to 1.98 +/- 1.76 ng/ml in phase 2 (p = 0.007), and from 2.72 +/- 0.97 to 1.67 +/- 0.71 ng/ml in phase 3 (p = < 0.001). However, there was no difference in the calculation of the PTH declination among the three phases (32, 50 and 42%, respectively). The incidence of
hypercalcemia was higher in using
calcitriol than without it (23 vs. 6%, p < 0.05), but there was no difference between intravenous and oral
calcitriol (35 vs. 19%). The above results suggested that both oral and intravenous
calcitriol, with lower doses and intermittent pulse
therapy, were equally effective in controlling
secondary hyperparathyroidism. The incidences of
hypercalcemia were similar in both oral and intravenous
calcitriol using 3.5 mEq/1
dialysate calcium concentration and
calcium carbonate as the chief
phosphate binder.