Long-term effect of intravenous calcitriol on the treatment of severe hyperparathyroidism, parathyroid gland mass and bone mineral density in haemodialysis patients.

ABSTRACT

We conducted this study on 15 chronic haemodialysis patients to evaluate the efficacy of i.v. calcitriol over a 1-year period in the treatment of severe secondary hyperparathyroidism (HPT), in particular its effect on bone mineral density (BMD) and parathyroid gland mass. Mean age was 39 +/- 11.9 (20-65) years and dialysis duration was 58 +/- 3 (19-130) months. i.v. calcitriol was given at a dose of 1 microg post-dialysis 3 times/week for 3 weeks; the dose was then adjusted to maintain the total serum calcium at less than 2.88 mmol/l. The maximum dose was 3 microg 3 times/week. Serum calcium (Ca) and phosphorus (P) were determined prior to treatment, then weekly for 6 weeks and every 2 weeks thereafter. Skeletal survey, dual photon densitometry and parathyroid ultrasound (US) were done prior to treatment and after 1 year. Bone biopsy was done in 10 patients at the beginning of treatment. There was a significant reduction (p < 0.01) in pre-treatment mid-region serum parathyroid hormone (PTH) from 1,476 +/- 895 to 489 +/- 485 P mol/l, as well as alkaline phosphatase (p < 0.04) from 236.5 +/- 221 to 116.3 +/- 49 U/l. This was without a significant increase in serum Ca (2.15 +/- 0.25 to 2.44 +/- 0.26 mmol/l, p = 0.08). Three patients had recurrent hypercalcaemia which responded to reduction of Ca in dialysate. There was a significant increase in BMD over the spine from 1.071 +/- 0.25 to 1.159 +/- 0.22 g/cm2 (p < 0.003) with a percent increase of 9.3 +/- 8.9% as well as over the femoral neck from 0.834 +/- 0.002 to 0.89 +/- 0.09 g/cm2 (p < 0.001) with a percent increase of 7.45 +/- 6.81%. Five patients had enlarged parathyroid glands by US and in 3 of these, there was a significant reduction to normal with treatment. Bone biopsy was done in 10 patients. Six patients had predominant hyperparathyroid bone disease and 4 had mixed uraemic osteodystrophy. In conclusion, long-term i.v. treatment with calcitriol is effective in the treatment of severe secondary HPT. PTH decreased without a significant increase in serum Ca. BMD also increases during this therapy.