Phenotype Presentation of Hypophosphatemic Rickets in Adults

• DOI: 10.1007/s00223-010-9373-0
• Publication Date: 2010-06-03T10:38:19Z
• Authors: Signe S. Beck-Nie...; Klaus Brusgaard; Lars M. Rasmussen; Kim Brixen; Bendt Brock-Jacobsen; Mette R. Poulsen; Peter Vestergaard; Stuart H. Ralston; Omar M. E. Albagha; Sven Poulsen; Dorte Haubek; Hans Gjørup; Hanne Hintze; Mette G. Andersen; Lene Heickendorff; Jacob Hjelmborg; Jeppe Gram
• Keywords: Adult; Male; 0301 basic medicine; Lumbar Vertebrae; Genetic Diseases, X-Linked; PHEX Phosphate Regulating Neutral Endopeptidase; Body Height; Fibroblast Growth Factors; Radiography; Fibroblast Growth Factor-23; Fractures, Bone; 03 medical and health sciences; Cross-Sectional Studies; Phenotype; Bone Density; Reference Values; Risk Factors; Osteomalacia; Humans; Female; Familial Hypophosphatemic Rickets; 10. No inequality; Periodontal Diseases

Hypophosphatemic rickets (HR) is a group of rare disorders caused by excessive renal phosphate wasting. The purpose of this cross-sectional study of 38 HR patients was to characterize the phenotype of adult HR patients. Moreover, skeletal and endodontic severity scores were defined to assess possible gender differences in disease severity in patients with genetically verified X-linked HR. Compared to normal reference data, i.e., z = 0, HR patients had significantly lower final height, with a mean difference in z-score of -1.9 (95% CI -2.4 to -1.4, P < 0.001). Compared to paired z-scores of final height, z-scores of leg length were significantly lower and those of sitting height were significantly higher (P < 0.001), resulting in disproportion as indicated by the significantly elevated sitting height ratio, mean difference in z-score of 2.6 (95% CI 2.1-3.1, P < 0.001). Z-scores of head circumference (median 1.4, range -0.4 to 5.5, P < 0.001) and z-scores of bone mineral density (BMD) of the lumbar spine (median 1.9, range -1.5 to 8.6, P < 0.001) were significantly elevated compared to normal reference data. The relative risk (RR) of fracture was reduced (RR = 0.34, 95% CI 0.20-0.57, P < 0.001). The skeletal severity score tended to be higher in males compared to females (P = 0.07), and no gender difference in endodontic severity was found. In conclusion, adult HR patients were characterized by short stature and were disproportioned. They had elevated BMD of the lumbar spine and a reduced risk of fractures. We found a tendency for males to be more severely affected than females.