Hereditary hypophosphataemic rickets: experience from a paediatric nephrology unit

introduction. rickets is a paediatric disease which should be suspected in children presenting with failure to thrive, motor developmental delay and orthopaedic abnormalities. although rare, hereditary hypophosphataemic rickets is the most common form of heritable rickets. patients and methods. retrospective observational study of all children with hypophosphataemic rickets observed at a paediatric nephrology unit of a tertiary paediatric hospital from 1982 to 2012, identified from the unit’s database. data collected included demographics, risk factors, pre-existing medical conditions, clinical, radiographic and laboratory findings, treatment and morbidity. results. eleven children with hypophosphataemic rickets were studied, with a median age at admission of 4.25 years (0.66-10.92). family history of rickets or orthopaedic abnormalities was found in five children. the first clinical manifestations were delayed/abnormal gait (7/11) and short stature (4/11). skeletal deformities were present in all children: genus valgum or varum (11/11), thickening of the wrists (7/11), rachitic rosary (4/11), frontal skull bossing (2/11), harrison’s groove (1/11). dental abscess was reported in one child and joint pain in six. laboratory findings included increased alkaline phosphatase (11/11), low serum phosphorus (11/11), normal serum calcium (10/11) and parathyroid hormone values (6/11) and low renal phosphorus reabsorption rate (9/10). none of the children had hypercalciuria. all children were treated with oral phosphorus and calcitriol (8/11 with lack of compliance). seven children were discharged with a median age of 16.5 years; all had bone deformities, 5/7 had short stature and 1/7 had nephrocalcinosis. discussion. hypophosphataemic rickets is a rare disease with significant long-term morbidity. it should be suspected in children presenting with short stature, developmental delay and orthopaedic abnormalities. increased alkaline phosphatase, low serum phosphorus with normal