TREATMENT OF REFRACTORY HYPERPARATHYROIDISM IN PATIENTS ON HEMODIALYSIS BY INTERMITTENT ORAL-ADMINISTRATION OF 1,25(OH)2 VITAMIN-D3

Intermittent oral administration of high dose 1,25(OH)2vitamin D3 was conducted in 7 patients associated with treatment-resistant secondary hyperparathyroidism (2nd HPT) on hemodialysis (HD) therapy. Each patient had a long history of HD therapy (range: 101-181 months, 145 +/- 29 months). Although serum calcium levels were maintained under the upper limit of the normal range with the appropriate dose of 1 alpha(OH)vitamin D3 every day before the present therapy, 2nd HPT could not have been controlled. The dose of 2-3-mu-g of 1,25(OH)2vitamin D3 3 times a week could successfully suppress serum levels of parathyroid hormone (iPTH) in all 7 patients after 20-32 weeks. The vitamin was given in the evening before each HD session and the dose and frequency of administration were dependent of the serum calcium level in each patient. After 20 weeks the iPTH-C and iPTH-intact levels decreased significantly from 35.0 +/- 15.8 to 18.6 +/- 11.7 ng/ml and from 533.2 +/- 200.0 to 249.5 +/- 136.2 pg/ml, respectively. The frequency of harmful elevations of serum calcium levels was not significantly increased in comparison with that in the previous period of the study, because serum calcium levels were strictly monitored with frequent checks. In conclusion, we could safely obtain an effect similar to the intravenous administration of the vitamin through the intermittent administration of a high oral dose 1,25(OH)2vitamin D3 in the treatment of refractory 2nd HPT in patients on HD therapy.