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.

Hypophosphatemic rickets (HR) is a rare hereditary disease in which dental problems in terms of spontaneous periapical infections are frequently reported. Most previous reports have been based on a small number of HR patients and have been published before the disease could be confirmed genetically. The aim of the present study was to describe the periapical and endodontic status of permanent teeth in patients with genetically and/or biochemically confirmed HR. The patients were recruited from a medical study on HR patients. The patients underwent a dental examination including a digital panoramic radiograph, which was scored for endodontically affected teeth (i.e. teeth with periapical radiolucencies and/or endodontically treated teeth). A total of 52 patients (age range: 5·7-74·5 years; 17 males and 35 females) were included. HR patients were characterised by a high number of endodontically affected teeth (mean: 4·2; s.d.: 5·0). The number of affected teeth rose significantly with age (P < 0·01), and no statistically significant gender difference was found. The relative distribution of endodontically affected teeth in the three tooth groups (incisors and canines, premolars, and molars) varied according to age. In the youngest age group, only incisors and canines were affected, while the relative proportion of affected premolars and molars increased with age. Endodontically affected teeth are common in HR patients, and the number of affected teeth increased significantly with age. Hence, the need for endodontic treatment among HR patients is comprehensive.