Children may present with symptoms that vary in severity

—Dr. Thomas Carpenter, XLH expert

Symptoms of XLH such as bowed legs and lower extremity abnormalities begin to manifest in early childhood, at the onset of weight-bearing.1-3

Chronic hypophosphataemia leads to defective growth plate development and bone mineralization4; children may present with:

Bone biopsy showing osteomalacia

Rickets and osteomalacia

  • Rickets is a disease in children characterized by abnormal mineralization of the bones as well as defective calcification of the cartilage growth plate at the epiphyses4
  • Osteomalacia is failure of mineralization of newly formed bone matrix4

Knock-knees in a child with XLH

Lower extremity abnormalities, including leg bowing, knock-knees, windswept deformities as well as short stature (predominant skeletal outcomes due to rickets and osteomalacia)1

Delayed walking as a result of rickets

Delayed walking, which can also result from rickets and osteomalacia3

Pain resulting from rickets

Pain, which may result from bearing weight on weak bones and misaligned joints5

Abnormal head shape in a child with XLH

Craniosynostosis, which is the premature fusion of the sutures in the skull2,3

Protrusion in part of brain because of XLH

Chiari malformations or the extension of the brain tissue into the spinal canal2,3

In addition to poor bone health, chronic hypophosphataemia can also affect the muscles in the body.5 Children may present with:

Muscle stiffness due to XLH

Stiffness, pain, and muscle weakness5

Wobbly walk due to weakened muscles from XLH

Gait disturbances, which result from weakened muscles in the legs5

Chronic hypophosphataemia can also lead to dental defects caused by improper mineralization of dentin, enlargement of the pulp chambers, and erosion of the enamel. Dental symptoms present as:

Tooth infection in a child with XLH

Dental abscesses and tooth loss1,3


1. Carpenter TO, Imel EA, Holm IA, et al. A clinician’s guide to X-linked hypophosphataemia. J Bone Miner Res. 2011;26(7):1381-1388. 2. Ruppe MD. X-Linked Hypophosphataemia. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. 3. Linglart A, Biosse-Duplan M, Briot K, et al. Therapeutic management of hypophosphataemic rickets from infancy to adulthood. Endocr Connect. 2014;3(1):R13-30. 4. Carpenter TO. Primary disorders of phosphate metabolism. In: De Groot LJ, Chrousos G, Dungan K, et al, eds. Endotext. South Dartmouth, MA; 2000. 5. Linglart A, Dvorak-Ewell M, Marshall A, et al. Impaired mobility and pain significantly impact the quality of life of children with X-linked hypophosphataemia [abstract]. Bone Abstracts. 2015;4:P198. 6. Data on file. Ultragenyx Pharmaceutical.