Abstract
From the demonstration by DELUCA et al. that 25-HCC is the active form of D3, it was postulated that some forms of VDRR may result from a decreased ability to convert D3 to 25-HCC and should respond to it. Following oral administration of tritiated D3, 4 patients with VDRR failed to develop significant plasma concentations of labeled 25-HCC compared to controls (< 1% vs. > 4% at 24 h and <3% vs. > 10% at 48 h). Five patients 3 with VDRR and 2 with osteomalacia) from two pedigrees with hypo9phosphatemic VDRR have been treated for periods of 2 to 8 months with increasing oral doses of 25-HCC in oil. All have responded symptomatically, chemically and radiographically (X-ray unchanged in 1 patient adequately treated less than 1 mo.). 4,800 U/day appears to be a minimal effective ‘healing’ dose. Maintenance does has not been established. No toxicity has been observed. Observations during unplanned transient periods off treatment indicate that the duration of action of 25-HCC in man is short compared to D2 or D3. These findings indicate that 25-HCC will prove to be an effective, safe form of therapy for VDRR.
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Seely, J., Coussons, H., Smith, J. et al. Effective Treatment of Hypophosphatemic Vitamin D Resistant Rickets (VDRR) with 25-Hydroxychole-calciferol (25-HCC). Pediatr Res 4, 451 (1970). https://doi.org/10.1203/00006450-197009000-00069
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DOI: https://doi.org/10.1203/00006450-197009000-00069