Oral administration of 24,25(OH)₂D₃ suppresses the serum parathyroid hormone levels of dialysis patients

We measured the serum parathyroid hormone (PTH) levels in 20 patients treated with continuous ambulatory peritoneal dialysis before and after oral treatment with 24,25-dihydroxyvitamin D₃- 24,25(OH)₂D₃. This metabolite was given in addition to existing treatment with 1α-OH-D₃ and calcium carbonate. Administration of 24,25(OH)₂D₃ led to a significant decrease in PTH levels (intact molecule) from 382 ± (SE) 65 to 245 ± 54 pg/ml in 9 patients whose initial levels were extremely high (p = 0.01). No side effects were observed. On the average, calcium values were unchanged and within the normal range throughout the study period; however, a few episodes of mild asymptomatic hypercalcemia occurred which responded quickly to reduction of the calcium carbonate dosage. The present study suggests that oral administration of 24,25(OH)₂D₃ combined with Iα-OH-D₃ is safe and capable of suppressing the raised serum PTH levels of end-stage renal disease patients without the danger of significant hypercalcemia.