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Clinical and radiographic findings in children

xray of leg
Bowed legs
xray visual
Rickets
xray knee visual
Knock knees

Predominant clinical findings in children include:4

  • Rickets
  • Lower extremity bowing
  • Leg abnormalities
  • Pain
  • Short stature
  • Gait disturbances

Evaluate skeletal symptoms through radiography

Other signs and symptoms may also include:5

  • Dental abscesses
  • Craniosynostosis
  • Chiari malformations

Family History

With known family history of XLH

XLH is inherited in an X-linked dominant pattern, so a positive family history of the disease supports the diagnosis. In a family with a history of XLH, screen other first-generation family members for XLH. This can help identify previously undiagnosed individuals.4,5

Without known family history of XLH

Since approximately 20% to 30% of XLH cases are spontaneous, it’s important to ask if your patient has a history of short stature, rickets, osteomalacia, osteoarthritis, and dental abscesses, all of which may indicate XLH.5

Biochemical findings

The following are predominant clinical findings in children and adults.

Evaluate age-normalized levels of fasting serum phosphorus for an accurate diagnosis. Low phosphorus levels and a low TmP/GFR ratio are the most relevant biochemical findings for XLH.4,5

Key biochemical findings for XLH4-6
Biochemical Test XLH
Fasting serum phosphorus
Down
1,25(OH)2D
Down or inappropriately normal
25(OH)D Normal
TmP/GFR
Down
ALP
Up
Serum calcium Normal
Urinary calcium
Normal to decreased
PTH Normal or slightly up

Confirmatory testing

In both children and adults, evaluating PHEX genetic variant status and FGF23 levels can help establish an accurate diagnosis for XLH.2,4,6

Confirm XLH:
Through a genetic analysis of the PHEX gene By checking for elevated intact FGF23 levels
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Prioritize testing your patient’s serum phosphorus levels in addition to clinical, radiographic, and other biologic findings in order to diagnose XLH.

Preventing further complications

The progressive nature of XLH may lead to increasing clinical consequences over time.5 Early diagnosis of XLH in both adults and children may help prevent complications.1,4,5

Comprehensive care for patients

Symptoms of XLH are nonspecific when considered individually and vary between patients. Accordingly, patient care requires a comprehensive team of healthcare professionals and specialists to provide disease education for your patients.1

These specialists may include:1

  • Endocrinologist
  • Nephrologist
  • General practitioner
  • Pediatrician
  • Physical therapists
  • Orthopedic surgeon
  • Rheumatologist
  • Pain specialist
  • Genetic counselor
  • Dentist

Connect the symptoms

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Suspect XLH?

Connect their symptoms and diagnose with the applicable tests.

Recognize the signs
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Patient case studies of XLH

See sample case studies of adults and children.

View patient cases
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XLH resources and community

Find resources for you and your patients to understand more about this rare condition.

Resources

1,25(OH)2D=1,25-dihydroxyvitamin D (calcitriol); 25(OH)D=25-hydroxyvitamin D (calcifediol); ALP=alkaline phosphatase; PTH=parathyroid hormone; TmP/GFR=ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate.

References:

1. Hamilton AA, et al. J Endocr Soc. 2022;6(8):bvac086. 2. Trombetti A, et al. Nat Rev Endocrino. 2022;18(6):366-384. 3. Carpenter TO, et al. J Bone Miner Res. 2011;26(7):1381-1388. 4. Haffner D, et al. Nat Rev Nephrol. 2019;15(7):435-455. 5. Dahir K, et al. J Endocr Soc. 2020;4(12):bvaa151. doi:10.1210/jendso/bvaa15. 6. 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.