[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"health-study-detail:100607055":3},{"organization":4,"armGroups":7,"interventions":10,"overallOfficials":12,"centralContacts":16,"locations":23,"responsibleParty":41,"collaborators":43,"id":60,"slug":61,"hasResults":62,"nctId":63,"briefTitle":64,"officialTitle":65,"acronym":10,"eligibilityCriteria":66,"healthyVolunteers":62,"sex":67,"minAge":68,"maxAge":69,"enrollmentInfo":70,"targetDuration":10,"studyType":73,"phases":10,"briefSummary":74,"conditions":75,"keywords":77,"overallStatus":26,"whyStopped":10,"lastUpdateSubmitDate":103,"lastUpdatePostDateStruct":104,"startDateStruct":107,"completionDateStruct":109,"leadSponsor":111,"locationsCount":112},{"fullName":5,"class":6},"University of Nottingham","OTHER",[8],{"label":9,"type":10,"description":11,"interventionNames":10},"XLH",null,"Children and young people with XLH treated with Burosumab",[13],{"name":14,"affiliation":5,"role":15},"James Law, BMBS, PhD, MRCPCH","PRINCIPAL_INVESTIGATOR",[17],{"name":18,"role":19,"phone":20,"phoneExt":21,"email":22},"James M Law, BMBS, PhD, MRCPCH","CONTACT","01159249924","82336","james.law@nottingham.ac.uk",[24],{"facility":25,"status":26,"city":27,"state":10,"zip":28,"country":29,"countryCode":30,"cosmosGeoPoint":31,"geoPoint":36,"contacts":37},"Nottingham University Hospitals NHS Trust","RECRUITING","Nottingham","NG7 2UH","United Kingdom","UK",{"type":32,"coordinates":33},"Point",[34,35],-1.15047,52.9536,{"lat":35,"lon":34},[38],{"name":39,"role":19,"phone":10,"phoneExt":10,"email":40},"Pooja Sachdev","pooja.sachdev@nhs.net",{"type":42,"investigatorFullName":10,"investigatorTitle":10,"investigatorAffiliation":10,"oldNameTitle":10,"oldOrganization":10},"SPONSOR",[44,45,47,49,51,53,56,58],{"name":25,"class":6},{"name":46,"class":6},"Birmingham Women's and Children's NHS Foundation Trust",{"name":48,"class":6},"University Hospitals Bristol and Weston NHS Foundation Trust",{"name":50,"class":6},"University Hospital Southampton NHS Foundation Trust",{"name":52,"class":6},"Sheffield Children's NHS Foundation Trust",{"name":54,"class":55},"Manchester University NHS Foundation Trust","OTHER_GOV",{"name":57,"class":6},"Newcastle-upon-Tyne Hospitals NHS Trust",{"name":59,"class":6},"Alder Hey Children's NHS Foundation Trust","100607055","effective-dosing-of-burosumab-in-xlh-100607055",false,"NCT07183579","Effective Dosing of Burosumab in XLH","A Retrospective Observational Study of the Effect of Dosing Regimen of Burosumab on Biochemical Control of Serum Phosphate Levels in Patients With X-linked Hypophosphataemia (XLH)","Inclusion Criteria:\n\n* A diagnosis of x-linked hypophosphataemia (XLH) including genetic confirmation of a PHEX mutation.\n* Has received at least 12 months of continuous Burosumab treatment under paediatric criteria (given Burosumab is not started till a child is 12 months old in England, the minimum age will, therefore, be 2 years old) prior to their 18th birthday.\n\nExclusion Criteria:\n\n* Burosumab received under adult criteria (patients who have received both Burosumab under paediatric arrangements and, subsequently, adult arrangements, can have data obtained during paediatric dosing included).","ALL","2 Years","18 Years",{"count":71,"type":72},120,"ESTIMATED","OBSERVATIONAL","X-linked hypophosphataemia (XLH) is a rare, hereditary condition. The genetic defect leads to low blood phosphate levels and vitamin D suppression. Phosphate is required for strong bones and teeth and to store energy in cells. Low phosphate leads to soft bones (rickets). Patients experience bowed legs, short stature, bone pain and dental pain.\n\nPrior to Burosumab, conventional treatment of XLH previously consisted of two medications. On this regimen, patients take oral phosphate supplements 4-6 times a day and an active form of vitamin D daily. This treatment can leave patients with residual symptoms. They report significant disabilities and reduced quality of life.\n\nBurosumab (Crysvita, Kyowa Kirin) is now the standard paediatric treatment for XLH. It is given once a fortnight by injection under the skin. Early studies used a starting dose of 0.4mg\u002Fkg per dose. NICE recommends a starting dose of 0.4mg\u002Fkg, a normal maintenance dose of 0.8mg\u002Fkg and a maximum of 2mg\u002Fkg (up to 90mg). The British National Formulary for Children (BNFC) gives the same advice.\n\nHowever, the European Medicines Agency recommends a starting dose of 0.8mg\u002Fkg per dose which is, therefore, the standard starting dose now. Some patients achieve symptom and biochemical control on less than 0.8 mg\u002Fkg per dose. They may be exposed to higher doses than necessary.\n\nTo date, approximately 200 patients have started on Burosumab in England. They are all managed by specialist centres. The rare status of XLH means there are relatively few patients in each centre. Treatment effects and trends can only be described by collating data from multiple centres.\n\nThe investigators will undertake a review across multiple English centres of the doses of Burosumab. The review will only collect data already in the patients' health records. It will look at factors affecting the starting dose. The investigators will assess the association between dose, blood markers and growth.",[76],"X-linked Hypophosphatemia (XLH)",[78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102],"Hypophosphatemia, X-Linked Dominant","Rickets","Burosumab","Monoclonal Antibodies","Alkaline Phosphatase","Parathyroid Hormone","Retrospective Studies","Observational Study","Multicenter Study","Dose-Response Relationship, Drug","Child","Adolescent","Pediatrics","X-Linked Hypophosphatemia (XLH)","Metabolic Bone Disease","Crysvita","FGF23 Antibody","Real-World Evidence","Pragmatic Clinical Study","Serum Phosphate","Nephrocalcinosis","Paediatric Endocrinology","Treatment Outcome","Adverse Events","Drug Administration Schedule","2026-05-05",{"date":105,"type":106},"2026-05-11","ACTUAL",{"date":108,"type":106},"2025-11-03",{"date":110,"type":72},"2026-07-01",{"name":5,"class":6},1]