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PubMed This is a summary of 98 peer-reviewed journal articles Updated
Pediatrics

X-linked Hypophosphatemia (XLH): A Patient Guide

At a Glance

X-linked hypophosphatemia (XLH) is a lifelong inherited disorder in which excess FGF23 makes the kidneys lose phosphate, weakening bones and teeth. Diagnosis uses blood and urine findings, and care may include specialist-supervised phosphate or burosumab treatment plus proactive dental monitoring.

X-linked hypophosphatemia (XLH) is a rare, lifelong condition that affects how your body processes phosphate (the form of phosphorus found in the body), a mineral essential for building and maintaining healthy bones and teeth. It is an inherited disorder caused by a change in a gene called PHEX, which leads the body to produce too much of a hormone called Fibroblast Growth Factor 23 (FGF23) [1][2]. This excess hormone acts like a “leaky faucet” in the kidneys, causing them to flush out too much phosphate into the urine while also preventing the body from making enough active vitamin D [3][4].

Because the body cannot hold onto the phosphate it needs, the bones and teeth suffer from impaired mineralization. In children, this primarily shows up as rickets, which can lead to bowed legs, a waddling gait, and slowed growth [5][6]. While active osteomalacia can occur in children, as patients move into adulthood the condition shifts primarily toward adult osteomalacia (a defective mineralization or softening of the bone matrix). This can cause chronic pain, stiffness, and “pseudofractures”—small, incomplete breaks in the weight-bearing bones that may not heal on their own [7][8]. Over time, adults may also experience joint issues, hearing loss, or a narrowing of the spinal canal [9][5].

Living well with XLH depends on a few key pillars of care. First, an accurate diagnosis is critical and relies on spotting a unique biochemical pattern: low phosphate levels in the blood paired with an inappropriately high or inappropriately normal level of the FGF23 hormone, alongside evidence of kidney phosphate wasting [9][10].

Important Medication Safety Note: You should never start, stop, combine, or change your XLH medications (such as mixing burosumab with oral phosphate) without direct supervision from your specialist. Combining them can cause dangerously high phosphate levels and organ damage.

While traditional treatments focused only on replacing the lost phosphate, newer therapies now target the FGF23 hormone itself to help counteract the underlying “leak” [1][11]. Second, dental health requires specialized attention. Because the internal structure of the teeth is affected by XLH, spontaneous abscesses can occur even without any cavities, making individualized, proactive dental visits a necessity [12][13].

Finally, it is vital to understand that XLH does not disappear once a person stops growing. The biological processes that waste phosphate continue throughout a person’s life, and stopping treatment can lead to a rapid return of symptoms and a loss of bone health, though any treatment changes should be carefully individualized [14][15]. Transitioning from pediatric to adult care ensures that the gains made in childhood are protected, allowing patients to manage their symptoms and maintain their physical function for the long term [16][17].

Glossary of Common Lab Terms

  • ALP (Alkaline Phosphatase): An enzyme marking bone turnover.
  • PTH (Parathyroid Hormone): A hormone regulating calcium.
  • TmP/GFR: A calculation measuring kidney phosphate wasting.

In this guide

6 chapters

01

Understanding XLH: The Biology and Inheritance of a Rare Disease

Learn how XLH causes phosphate loss through FGF23 and PHEX mutations, follows X-linked dominant inheritance, and affects family planning and emotional wellbeing.

02

XLH Symptoms and Warning Signs Across the Lifespan

Learn how X-linked hypophosphatemia symptoms change from childhood to adulthood, including rickets, bone pain, pseudofractures, and urgent warning signs.

03

The Diagnostic Path: Labs, Genetics, and Differentials

X-linked hypophosphatemia diagnosis: Learn about phosphate labs, TmP/GFR, FGF23, PHEX testing, and how doctors distinguish rickets, Fanconi syndrome, and TIO.

04

Standard of Care Treatment for XLH

Learn about XLH treatment, including burosumab, phosphate and active vitamin D, safety monitoring, side effects, and how care differs for children and adults.

05

Dental Health and Daily Life with XLH

Learn how XLH affects teeth and daily life, including spontaneous abscesses, preventive dental care, physical therapy, surgery, pain, fatigue, and support.

06

Long-Term Care: Monitoring and Transitioning to Adulthood

Learn how to monitor X-linked hypophosphatemia in adulthood, prevent treatment gaps, track kidney and dental health, and plan a safe transition to adult care.

Common questions in this guide

What is X-linked hypophosphatemia, and what causes it?
XLH is a rare inherited condition that affects the body's handling of phosphate, a mineral needed for healthy bones and teeth. A change in the PHEX gene leads to too much FGF23, so the kidneys remove excess phosphate in urine and limit active vitamin D production.
What symptoms can XLH cause in children and adults?
In children, XLH can cause rickets with bowed legs, a waddling gait, and slowed growth. In adults, ongoing phosphate loss can cause softening of the bones, bone pain, stiffness, and pseudofractures. Joint problems, hearing loss, spinal canal narrowing, and dental abscesses may also occur.
How is XLH diagnosed?
Doctors look for low phosphate in the blood, an FGF23 level that is too high or not appropriately low, and evidence that the kidneys are losing phosphate. Results should be interpreted using age-specific ranges by a clinician familiar with XLH.
Does XLH go away after childhood?
No. The kidney phosphate-wasting process continues throughout life, even after growth ends. Stopping treatment can cause symptoms to return quickly and harm bone health, so any change should be planned with a specialist.
What treatments are used for XLH?
Traditional treatment replaces lost phosphate with oral phosphate supplements. Newer disease-targeted treatment, such as burosumab, targets the effects of excess FGF23. Burosumab and oral phosphate should not be started, stopped, combined, or changed without direct specialist supervision because phosphate levels can become dangerously high and damage organs.
Why does XLH require special dental care?
XLH can affect the internal structure of teeth, so spontaneous abscesses may develop even when there are no cavities. Regular, proactive dental visits should be individualized with the dental team and coordinated with medical care.
How should XLH care change as a child becomes an adult?
XLH remains lifelong, so care should transition from pediatric to adult clinicians rather than stop when growth ends. Ongoing monitoring of symptoms, bone health, kidney health, and teeth helps protect mobility and the progress made during childhood. The care team may include a medical specialist, dentist, and physical therapist.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Do my (or my child's) lab results show the 'signature' biochemical pattern of XLH, and how do they compare to age-specific ranges?
  2. 2.Since XLH is a lifelong condition, how will our medical and dental care plan change as I (or my child) move from childhood into adulthood?
  3. 3.How many patients with XLH does this clinic currently manage, and which other specialists—like dentists or physical therapists—are part of our core care team?
  4. 4.If we are considering a disease-targeted therapy, what are the specific benefits and monitoring requirements compared to traditional phosphate supplements?
  5. 5.What is our long-term plan for monitoring kidney health and dental health, and how often should we be scheduling these check-ups?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (17)
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    Phosphatonins: From Discovery to Therapeutics.

    Kritmetapak K, Kumar R

    Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists 2023; (29(1)):69-79 doi:10.1016/j.eprac.2022.09.007.

    PMID: 36210014
  2. 2

    FGF23 and its role in X-linked hypophosphatemia-related morbidity.

    Beck-Nielsen SS, Mughal Z, Haffner D, et al.

    Orphanet journal of rare diseases 2019; (14(1)):58 doi:10.1186/s13023-019-1014-8.

    PMID: 30808384
  3. 3

    X-linked hypophosphataemia.

    Kamenický P, Briot K, Munns CF, Linglart A

    Lancet (London, England) 2024; (404(10455)):887-901 doi:10.1016/S0140-6736(24)01305-9.

    PMID: 39181153
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    Diagnosis and management of X-linked hypophosphatemia in children and adolescent in the Gulf Cooperation Council countries.

    Al Juraibah F, Al Amiri E, Al Dubayee M, et al.

    Archives of osteoporosis 2021; (16(1)):52 doi:10.1007/s11657-021-00879-9.

    PMID: 33660084
  5. 5

    The Lifelong Impact of X-Linked Hypophosphatemia: Results From a Burden of Disease Survey.

    Skrinar A, Dvorak-Ewell M, Evins A, et al.

    Journal of the Endocrine Society 2019; (3(7)):1321-1334 doi:10.1210/js.2018-00365.

    PMID: 31259293
  6. 6

    The Diagnosis and Therapy of XLH.

    Böckmann I, Haffner D

    Calcified tissue international 2025; (116(1)):66 doi:10.1007/s00223-025-01374-w.

    PMID: 40295317
  7. 7

    Burosumab Improved Histomorphometric Measures of Osteomalacia in Adults with X-Linked Hypophosphatemia: A Phase 3, Single-Arm, International Trial.

    Insogna KL, Rauch F, Kamenický P, et al.

    Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2019; (34(12)):2183-2191 doi:10.1002/jbmr.3843.

    PMID: 31369697
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    X-linked hypophosphatemia: Management and treatment prospects.

    Lambert AS, Zhukouskaya V, Rothenbuhler A, Linglart A

    Joint bone spine 2019; (86(6)):731-738 doi:10.1016/j.jbspin.2019.01.012.

    PMID: 30711691
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    The Metabolic Bone Disease X-linked Hypophosphatemia: Case Presentation, Pathophysiology and Pharmacology.

    Vincze J, Skinner BW, Tucker KA, et al.

    Life (Basel, Switzerland) 2021; (11(6)) doi:10.3390/life11060563.

    PMID: 34203792
  10. 10

    X-Linked Hypophosphatemic Rickets: Multisystemic Disorder in Children Requiring Multidisciplinary Management.

    Baroncelli GI, Mora S

    Frontiers in endocrinology 2021; (12()):688309 doi:10.3389/fendo.2021.688309.

    PMID: 34421819
  11. 11

    Burosumab in X-linked hypophosphatemia: a profile of its use in the USA.

    Lyseng-Williamson KA

    Drugs & therapy perspectives : for rational drug selection and use 2018; (34(11)):497-506 doi:10.1007/s40267-018-0560-9.

    PMID: 30459508
  12. 12

    Early Dental Manifestations and Multidisciplinary Management of X-Linked Hypophosphatemic Rickets in a Pediatric Patient: A Case Report.

    Mitova N, Petkova-Ninova V, Popova Y

    Children (Basel, Switzerland) 2025; (13(1)) doi:10.3390/children13010016.

    PMID: 41597024
  13. 13

    Pulp chamber features, prevalence of abscesses, disease severity, and PHEX mutation in X-linked hypophosphatemic rickets.

    Baroncelli GI, Zampollo E, Manca M, et al.

    Journal of bone and mineral metabolism 2021; (39(2)):212-223 doi:10.1007/s00774-020-01136-8.

    PMID: 32772199
  14. 14

    Safety and efficacy of burosumab in improving phosphate metabolism, bone health, and quality of life in adolescents with X-linked hypophosphatemic rickets.

    Baroncelli GI, Grandone A, Aversa A, et al.

    European journal of medical genetics 2024; (70()):104958 doi:10.1016/j.ejmg.2024.104958.

    PMID: 38950880
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    Asia-Pacific Consensus Recommendations on X-Linked Hypophosphatemia: Diagnosis, Multidisciplinary Management, and Transition From Pediatric to Adult Care.

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    PMID: 37283655
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    X-Linked Hypophosphatemia Management in Adults: An International Working Group Clinical Practice Guideline.

    Khan AA, Ali DS, Appelman-Dijkstra NM, et al.

    The Journal of clinical endocrinology and metabolism 2025; (110(8)):2353-2370 doi:10.1210/clinem/dgaf170.

    PMID: 40243526
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    Experts' consensus on the management and treatment of individuals with X-linked hypophosphatemia across lifespan.

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    PMID: 40591205

This XLH guide is for informational purposes only and does not constitute medical advice. Do not change phosphate, burosumab, or other care without guidance from your specialist and dental team.

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