Short- and Long-Term Outcome of Patients with Pseudo-Vitamin D Deficiency Rickets Treated with Calcitriol

Background: Pseudo-vitamin D deficiency rickets (PDDR; OMIM 264700) is a rare autosomal recessive disorder caused by mutations in the CYP27B1 gene, leading to an inability to synthesize 1 alpha,25-dihydroxyvitamin D-3 (calcitriol). The long-term (>1 yr) effects of calcitriol replacement treatment have not been reported. Materials and Methods: Thirty-nine patients (20 females) with PDDR received calcitriol for periods of 2.0-26 yr. In 21 patients, data were available at diagnosis and during the first 2 yr of treatment with calcitriol. Twenty-five patients had reached their final height at the time of this analysis. Results: The most common presenting features were active rickets, neurological signs, and short stature. Treatment with calcitriol resulted in the normalization of biochemical parameters and mean lumbar spine areal bone mineral density z-scores within 3 months, whereas height z-scores increased more gradually. As to long-term effects, adult patients who had received calcitriol before the pubertal growth spurt (n = 11) had normal height, whereas patients who were treated with calcitriol only after puberty (n = 14) on average were short (height z-score -2.2). Lumbar spine areal bone mineral density z-scores were normal in all patients who had achieved final height. Nine women had 19 pregnancies, which all were without complications. All newborns were eucalcemic at birth. Conclusion: Treatment with calcitriol started in infancy results in short- and long-term correction of all clinical, biochemical, and radiological abnormalities related to PDDR. (J Clin Endocrinol Metab 96: 82-89, 2011)