INTRAMUSCULAR CALCITRIOL FOR UREMIC CHILDREN WITH SEVERE HYPERPARATHYROIDISM AND HYPERCALCEMIA

The effect of intramuscular calcitriol was evaluated in five children (aged 1-16 years) with severe chronic renal failure and hyperparathyro idism [range of intact parathyroid hormone (PTH) 400-1,200 pg/ml]. All five children had been on oral calcitriol or la-hydroxyvitamin D-3 tr eatment (5-20 ng/kg per day), but an adequate, efficacious dosage coul d not be achieved since any attempt of increasing the dosage resulted in severe hypercalcaemia (>2.9 mmol/l). Intramuscular calcitriol was g iven three times weekly for 5 months at an initial dosage of 65-70 ng/ kg to all but one patient who received 100 ng/kg. In the first three p atients, treatment resulted in an 86%-98% fall in serum PTH compared w ith baseline levels and serum calcium never exceeded 2.65 mmol/l, exce pt for one episode of hypercalcaemia in one patient. In the last two p atients, serum calcium rose above normal limits, thus calcitriol had t o be discontinued several times and then restarted at a lower dosage ( 40 ng/kg); PTH fell by 61% and 73%, respectively, compared with basal values. All patients had very low pre-treatment levels of serum 1,25-d ihydroxyvitamin D-3 (5-15 pg/ml) which were normalized (35-56 pg/ml) b y the intramuscular calcitriol-treatment. Serum phosphorus and magnesi um did not vary in any of the five patients. No side effects were obse rved at the injection site. Intramuscular calcitriol seems a useful th erapeutic option for patients with severe hyperparathyroidism associat ed with a high serum calcium level when treated with conventional oral calcitriol.