Intramuscular calcitriol for uraemic children with severe hyperparathyroidism and hypercalcaemia

The effect of intramuscular calcitriol was evaluated in five children (aged 1–16 years) with severe chronic renal failure and hyperparathyroidism [range of intact parathyroid hormone (PTH) 400–1,200 pg/ml]. All five children had been on oral calcitriol or 1α-hydroxyvitamin D3 treatment (5–20 ng/kg per day), but an adequate, efficacious dosage could not be achieved since any attempt of increasing the dosage resulted in severe hypercalcaemia (>2.9 mmol/l). Intramuscular calcitriol was given 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 patients, treatment resulted in an 86%–98% fall in serum PTH compared with baseline levels and serum calcium never exceeded 2.65 mmol/l, except for one episode of hypercalcaemia in one patient. In the last two patients, serum calcium rose above normal limits, thus calcitriol had to 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-dihydroxyvitamin D3 (5–15 pg/ml) which were normalized (35–56 pg/ml) by the intramuscular calcitrioltreatment. Serum phosphorus and magnesium did not vary in any of the five patients. No side effects were observed at the injection site. Intramuscular calcitriol seems a useful therapeutic option for patients with severe hyperparathyroidism associated with a high serum calcium level when treated with conventional oral calcitriol.