Comparing Calcitriol Doses in Pediatric Patients with X-Linked Hypophosphatemia

Citing that dosage recommendations have varied in previous studies, researchers evaluated the efficacy and safety of different doses of calcitriol in a prospective cohort of Chinese pediatric patients with X-linked hypophosphatemia (XLH). In the article, published in Osteoporosis International, the study’s lead author, C. Jin, suggested that “a dose of 40 ng/kg/day calcitriol, compared with 20 ng/kg/day, was more effective in relieving the rickets, with similar safety outcomes.”

The study included 68 children with XLH who received either 40 or 20 ng/kg of calcitriol daily. The primary endpoints of interest were total Thacher ricket severity score (RSS) change from baseline to 12 and 24 months, difference in serum total alkaline phosphate (TALP) level, fasting serum phosphate level, body height Z-score, and frequency of dental abscesses. Safety endpoints including renal ultrasound nephrocalcinosis grades, fasting serum and 24-hour urine calcium levels, and incidence of hyperparathyroidism.

According to the investigators, “the decrease in the total RSS from baseline was more significant in the high-dose group at 12 (difference: 0.87; p = 0.049) and 24 month (difference: 1.23; p = 0.011).” Additionally, the serum TALP level was significantly lower in the high-dose group at six months. Pi level, height Z-score change, frequency of dental abscess and ratio of de novo nephrocalcinosis were comparable. Finally, a lower incidence of secondary hyperparathyroidism was observed in the high-dose patients (p <0.0001).

For the first time, according to Jin and colleagues, 40 ng/kg/day calcitriol was shown to be more effective than 20 ng/kg/day in children with XLH, without increasing adverse events. In closing, the authors added that “further investigations were expected to set more dose groups.”