Clinical and metabolic features in childhood hypophosphatemic rickets

Abstract

Background: Hypophosphatemic rickets is a rare disease, related to renal phosphate waste, which cause bone deformities, and lead to walking abnormalities and to the reduction in the quality of life. Clinical recommendations in different countries vary in medications, recommended doses and surgery approach. The main aim was to analyze phosphate metabolism in children with hypophosphatemic rickets and to evaluate results of conservative and surgical therapy. Methods: We analyzed medical histories of 15 children with hypophosphatemic rickets and investigated phosphate metabolism, including the measurement of serum intact fibroblast growth factor 23 and X-ray bone densitometry. Routine biochemical tests were assessed with our laboratory reference data, the level of iFGF-23 in hypophosphatemic children was compared with the same values in 18 healthy children. Results: We investigated 15 girls with hypophosphatemic rickets, aged of from 3 years 9 months to 18 years 7 months. All children were treated with alphacalcidol and inorganic phosphate (in dose from 16.21 to 103.3 mg/kg, during from 1 to 114 months). Eleven (73%) children had surgical correction of bone deformations, starting at the age of from 3 to 12 years. Ten (91%) of them had the relapse of bone deformations. Two of four children undergone to the correction of bone abnormalities on alphacalcidol and phosphate therapy without surgery. The level of iFGF-23 in children with hypophosphatemic rickets was 73.11 pg/ml, and exceed iFGF-23 in control group (22.92 pg/ml), p =0,009. Conclusion: Early surgical treatment of bone deformations is not indicated in hypophosphatemic rickets because of risk of recurrence, observed in 91% of our patients. There could be spontaneous correction of bone deformation during conservative therapy, when it is started early.