[Calcitriol dose optimization in the treatment of secondary hyperparathyroidism during dialysis. Results at 6 months]. / Optimización de la dosis de calcitriol en el tratamiento del hiperparatiroidismo secundario en diálisis. Resultados a seis meses.

One recent report have recommended to start calcitriol therapy with a dose according to PTH levels, rather than starting with a fixed dose increasing it according to PTH response. As there are no clinical studies supporting this strategy we tested his hypothesis. Haemodialysis patients from 28 centres (N = 141) were included, the aim was to achieve a PTH between 100 and 285 pg/mL (goal) in 6 months. The main inclusion criteria were: serum PTH > 250 pg/mL, Ca < 10.5 mg/dL, P < 6.5 mg/dL and Ca x P < 60. Patients were divided according PTH into 4 groups and calcitriol was dosed accordingly. A (PTH 250-350; 0.5 microgram), B (PTH 351-550; 1-1.5 micrograms), C (PTH 551-750; 1.5-2 micrograms) and D (PTH < 750 pg/mL; 2-3 micrograms). PTH was measured monthly in groups A, B, C and fortnightly in D. Ca, P and Ca x P were measured fortnightly (groups A, B, C) and weekly in D. According to PTH results calcitriol was modified, reducing 50% if PTH was suppressed > 60%, and increasing 50% if PTH suppression was < 15% (fig. 1). Patients were stopped treatment and excluded from study when Ca, P and Ca x P product trespass the established inclusion criteria. The study was completed by 100 patients, 34 with strict compliance of the protocol (compliant), and 66 with one o more protocol violations, the most frequent was lack of strict adherence to the dosing regime (non compliant). Among the compliant, 82.4% reached the goal in contrast with 13.8% of the non compliant (p < 0.001) (table II). In addition, the compliant showed (all patients in all groups) a greater and significant decrease in PTH (from 616 +/- 288 to 202 +/- 82), by contrast, 21.5% of the non-compliant did not decrease--but increased--their PTH levels. The compliant showed also fewer side effects than the non-compliant (25% vs 55.6%, p < 0.006). These results demonstrate several advantages when starting calcitriol therapy with a dose proportional to the severity of HPTH.