COMPARISON OF INTERMITTENT AND CONTINUOUS ORAL-ADMINISTRATION OF CALCITRIOL IN DIALYSIS PATIENTS - A RANDOMIZED PROSPECTIVE TRIAL

Intermittent bolus administration of calcitriol - i.e., 1,25-dihydroxy cholecalciferol or 1,25-(OH)(2)D-3 - is highly efficacious in dialysis patients. In experimental studies, intermittent administration of cal citriol is superior to continuous administration in suppressing prepro parathyroid hormone (PTH) mRNA and circulating PTH concentrations. In a randomized, prospective, open multicenter trial 45 dialysis patients with elevated 1,84-iPTH (greater than or equal to 20 pmol/l, normal 1 -6 pmol/l) levels were randomly allocated to daily administration of 0 .75 mu g calcitriol (continuous) or twice weekly administration (inter mittent); the two protocols provided an identical total weekly doses o f 5.25 mu g calcitriol. Patients were dialyzed with a dialysate Ca con centration of 1.75 mmol/l and had oral CaCO3 or Ca acetate. 1,84-iPTH (immunoradiometric assay) and serum Ca and Pi levels were measured wee kly. At the beginning of the study, the median 1,84-iPTH value was 37 pmol/l (range 20-115) in the intermittent versus 36 pmol/l (range 21-7 2) in the continuous calcitriol group. After 2 weeks, the median 1,84- iPTH level was 18.5 pmol/l (range 1.4-106) versus 18 pmol/l (range 1.2 -48). After 12 weeks, 11 of 21 of the patients in the intermittent and 18 of 24 patients in the continuous group had reached the treatment g oal, i.e., 1,84-iPTH less than or equal to 10 pmol/l without hypercalc emia or hyperphosphatemia. There were seven episodes of hypercalcemia (> 2.7 mmol/l) in the intermittent versus two in the continuous group; the mean peak Ca level was 2.8 mmol/l (range 2.76-3.0) versus 2.9 mmo l/l (range 2.74-3.06). There were 21 versus 17 episodes, respectively, of hyperphosphatemia (> 2.2 mmol/l).