Abstract
2 patients with familial hypophosphatemic rickets (FHR) and 1 patient with idiopathic Fanconi syndrome under oral phosphate treatment were given 1,25(OH)2CC (0,75-1,5 μg/day) and the effects on the intestinal absorption and renal tubular handling of Pi were studied. Intestinal absorption of Pi: During a 3-hour oral loading test (300 mg Pi) the serum Pi levels were significantly higher after 1,25(OH)2CC treatment, and ionized serum calcium levels did not change. Thus, in the 3 patients Pi intestinal absorption was increased by 1,25 (OH)2CC.
Renal handling of Pi: In the 2 patients with FHR, 1,25 (OH)2CC increased Pi filtered load and absolute tubular reabsorption and decreased fractional clearance (before treatment: 34 and 39%, after treatment: 8 and 12% respectively). In the patient with idiopathic Fanconi syndrome, 1,25(OH)2CC increased Pi filtered load and absolute tubular reabsorption but the fractional clearance did not change. This strongly suggests 2 different pathophysiological mechanisms responsible for the renal tubular loss of Pi. In the 3 patients, 1,25(OH)2CC markedly improved the bone lesions.
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Laufer, D., Sizonenko, P. & Paunier, L. Familial hypophosphatemic rickets and idiopathic Fanconi syndrome. Effect of 1,25 (OH)2 cholecalciferol (Rocaltrol R) (1,25 (OH)2CC) on metabolism of inorganic phosphate (Pi). Pediatr Res 14, 1418 (1980). https://doi.org/10.1203/00006450-198012000-00058
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DOI: https://doi.org/10.1203/00006450-198012000-00058