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XLH is a hereditary, progressive, and lifelong disease1

XLH is a chronic and rare disease—up to 1 in 20,000 people have it—characterized by hypophosphatemia that impacts the skeletal and muscular health of children and adults.1,2 If the underlying pathophysiological processes causing skeletal manifestations of XLH in early childhood are not optimally treated, these defects will progress into adolescence and adulthood, leading to significant pathology.3

XLH can often be misdiagnosed and should be distinguished from:4,5

Drawing of a transparent knee with visible bones

Nutritional rickets or osteomalacia

Illustration of phosphorus from the chemical table

Hypophosphatasia

Drawing of two parallel bones

Other hereditary rickets

Drawing of two parallel bones that bend inward

Physiologic bowing

Screening family members of patients with XLH may help identify previously undiagnosed individuals.6

In XLH, increased FGF23 is the source of chronic hypophosphatemia3

Illustration of protein hormones labelled FGF23

Excess FGF23

FGF23 is a protein hormone produced by osteocytes in the bones to regulate serum phosphorus levels. PHEX gene variants cause excess FGF23 activity.6

Illustration of the FGF23 hormones entering a kidney

Reduced renal phosphorus absorption

Excess FGF23 results in excess phosphorus excretion.6

Illustration of the FGF23 hormones entering the small intestine

Decreased intestinal phosporus absorption

Reduced active vitamin D results in decreased phosporus absorption in the small intestine.6

Illustration of a weakened bone with many small holes throughout

Chronic hypophosphatemia

Due to loss of phosphorus, bones become weakened.3

PHEX=phosphate regulating endopeptidase X-linked

Evidence suggests that restoring phosphate homeostasis improves or prevents progression of many of the clinical manifestations associated with chronic hypophosphatemia.7

Supporting phosphate homeostasis

Until recently, pharmacologic management of chronic hypophosphatemia was limited to supplementation with phosphate salts, together with active vitamin D analogs to avoid decreased serum calcium and elevated PTH.7

While phosphate supplements may help, they may not restore phosphate homeostasis due to:

  • Persistent renal losses7
  • Effectiveness in ameliorating the effects of chronic hypophosphatemia7
  • Association with risks of hypercalciuria, nephrocalcinosis, kidney failure, and secondary/tertiary hyperparathyroidism7
  • Palatability issues and gastrointestinal symptoms may impact adherence7

Help restore and maintain serum phosphorus levels with CRYSVITA8

How it works

Explore compelling real-life cases of adult and pediatric patients with XLH

Managing XLH patients
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Actor portrayal

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Indication

CRYSVITA® (burosumab-twza) is a fibroblast growth factor 23 (FGF23) blocking antibody indicated for the treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients 6 months of age and older.

Important Safety Information

CONTRAINDICATIONS

CRYSVITA is contraindicated:

  • In concomitant use with oral phosphate and/or active vitamin D analogs (e.g., calcitriol, paricalcitol, doxercalciferol, calcifediol) due to the risk of hyperphosphatemia.
  • When serum phosphorus is within or above the normal range for age.
  • In patients with severe renal impairment or end stage renal disease because these conditions are associated with abnormal mineral metabolism.

WARNINGS AND PRECAUTIONS

Hypersensitivity

  • Hypersensitivity reactions (e.g., rash, urticaria) have been reported in patients with CRYSVITA. Discontinue CRYSVITA if serious hypersensitivity reactions occur and initiate appropriate medical treatment.

Hyperphosphatemia and Risk of Nephrocalcinosis

  • Increases in serum phosphorus to above the upper limit of normal may be associated with an increased risk of nephrocalcinosis. For patients already taking CRYSVITA, dose interruption and/or dose reduction may be required based on a patient’s serum phosphorus levels.

Injection Site Reactions

  • Administration of CRYSVITA may result in local injection site reactions. Discontinue CRYSVITA if severe injection site reactions occur and administer appropriate medical treatment.

ADVERSE REACTIONS

Pediatric Patients

  • Adverse reactions reported in 10% or more of CRYSVITA-treated pediatric XLH patients across three studies are: pyrexia (55%, 44%, and 62%), injection site reaction (52%, 67%, and 23%), cough (52%), vomiting (41%, 48%, and 46%), pain in extremity (38%, 46%, and 23%), headache (34% and 73%), tooth abscess (34%, 15%, and 23%), dental caries (31%), diarrhea (24%), vitamin D decreased (24%, 37%, and 15%), toothache (23% and 15%), constipation (17%), myalgia (17%), rash (14% and 27%), dizziness (15%), and nausea (10%).
  • Postmarketing experience reported in CRYSVITA-treated pediatric XLH patients: blood phosphorus increased.

Adult Patients

  • Adverse reactions reported in 10% or more of CRYSVITA-treated pediatric XLH patients across three studies are: pyrexia (55%, 44%, and 62%), injection site reaction (52%, 67%, and 23%), cough (52%), vomiting (41%, 48%, and 46%), pain in extremity (38%, 46%, and 23%), headache (34% and 73%), tooth abscess (34%, 15%, and 23%), dental caries (31%), diarrhea (24%), vitamin D decreased (24%, 37%, and 15%), toothache (23% and 15%), constipation (17%), myalgia (17%), rash (14% and 27%), dizziness (15%), and nausea (10%).
  • Spinal stenosis is prevalent in adults with XLH, and spinal cord compression has been reported. It is unknown if CRYSVITA therapy exacerbates spinal stenosis or spinal cord compression.

USE IN SPECIFIC POPULATIONS

  • There are no available data on CRYSVITA use in pregnant women to inform a drug-associated risk of adverse developmental outcomes. Serum phosphorus levels should be monitored throughout pregnancy. Report pregnancies to the Kyowa Kirin, Inc. Adverse Event reporting line at 1-844-768-3544.
  • There is no information regarding the presence of CRYSVITA in human milk or the effects of CRYSVITA on milk production or the breastfed infant. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for CRYSVITA and any potential adverse effects on the breastfed infant from CRYSVITA or from the underlying maternal condition.

PATIENT COUNSELLING INFORMATION

  • Advise patients not to use any oral phosphate and/or active vitamin D analog products.
  • Instruct patients to contact their physician if hypersensitivity reactions, injection site reactions, and restless legs syndrome induction or worsening of symptoms occur.

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Kyowa Kirin, Inc. at 1-844-768-3544.

For important risk and use information, please see the full Prescribing Information for CRYSVITA.

Indication

CRYSVITA® (burosumab-twza) is a fibroblast growth factor 23 (FGF23) blocking antibody indicated for the treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients 6 months of age and older.

Important Safety Information

CONTRAINDICATIONS

CRYSVITA is contraindicated:

  • In concomitant use with oral phosphate and/or active vitamin D analogs (e.g., calcitriol, paricalcitol, doxercalciferol, calcifediol) due to the risk of hyperphosphatemia.
  • When serum phosphorus is within or above the normal range for age.
  • In patients with severe renal impairment or end stage renal disease because these conditions are associated with abnormal mineral metabolism.

WARNINGS AND PRECAUTIONS

Hypersensitivity

  • Hypersensitivity reactions (e.g., rash, urticaria) have been reported in patients with CRYSVITA. Discontinue CRYSVITA if serious hypersensitivity reactions occur and initiate appropriate medical treatment.

Hyperphosphatemia and Risk of Nephrocalcinosis

  • Increases in serum phosphorus to above the upper limit of normal may be associated with an increased risk of nephrocalcinosis. For patients already taking CRYSVITA, dose interruption and/or dose reduction may be required based on a patient’s serum phosphorus levels.

Injection Site Reactions

  • Administration of CRYSVITA may result in local injection site reactions. Discontinue CRYSVITA if severe injection site reactions occur and administer appropriate medical treatment.

ADVERSE REACTIONS

Pediatric Patients

  • Adverse reactions reported in 10% or more of CRYSVITA-treated pediatric XLH patients across three studies are: pyrexia (55%, 44%, and 62%), injection site reaction (52%, 67%, and 23%), cough (52%), vomiting (41%, 48%, and 46%), pain in extremity (38%, 46%, and 23%), headache (34% and 73%), tooth abscess (34%, 15%, and 23%), dental caries (31%), diarrhea (24%), vitamin D decreased (24%, 37%, and 15%), toothache (23% and 15%), constipation (17%), myalgia (17%), rash (14% and 27%), dizziness (15%), and nausea (10%).
  • Postmarketing experience reported in CRYSVITA-treated pediatric XLH patients: blood phosphorus increased.

Adult Patients

  • Adverse reactions reported in more than 5% of CRYSVITA-treated adult XLH patients and in at least 2 patients more than placebo in one study are: back pain (15%), headache (13%), tooth infection (13%), restless legs syndrome (12%), vitamin D decreased (12%), dizziness (10%), constipation (9%), muscle spasms (7%), and blood phosphorus increased (6%).
  • Spinal stenosis is prevalent in adults with XLH, and spinal cord compression has been reported. It is unknown if CRYSVITA therapy exacerbates spinal stenosis or spinal cord compression.

USE IN SPECIFIC POPULATIONS

  • There are no available data on CRYSVITA use in pregnant women to inform a drug-associated risk of adverse developmental outcomes. Serum phosphorus levels should be monitored throughout pregnancy. Report pregnancies to the Kyowa Kirin, Inc. Adverse Event reporting line at 1-844-768-3544.
  • There is no information regarding the presence of CRYSVITA in human milk or the effects of CRYSVITA on milk production or the breastfed infant. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for CRYSVITA and any potential adverse effects on the breastfed infant from CRYSVITA or from the underlying maternal condition.

PATIENT COUNSELLING INFORMATION

  • Advise patients not to use any oral phosphate and/or active vitamin D analog products.
  • Instruct patients to contact their physician if hypersensitivity reactions, injection site reactions, and restless legs syndrome induction or worsening of symptoms occur.

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Kyowa Kirin, Inc. at 1-844-768-3544.

For important risk and use information, please see the full Prescribing Information for CRYSVITA.

Reference:

  • 1. Hamilton AA, et al. Whole Body, Whole Life, Whole Family: Patients’ Perspectives on X-Linked Hypophosphatemia. Journal of the Endocrine Society. 2022;6(8). 2. Beck-Nielsen SS, et al. FGF23 and its role in X-linked hypophosphatemia-related morbidity. Orphanet Journal of Rare Diseases. 2019;14(1):58. 3. Glorieux FH, et al. Potential influences on optimizing long-term musculoskeletal health in children and adolescents with X-linked hypophosphatemia (XLH). Orphanet J Rare Dis. 2022;17(1):30. 4. Carpenter TO, et al. A clinician's guide to X-linked hypophosphatemia. J Bone Miner Res. 2011;26(7):1381-1388. 5. Cianferotti L. Osteomalacia Is Not a Single Disease. Int J Mol Sci. 2022;23(23). 6. Dahir K, et al. X-Linked Hypophosphatemia: A New Era in Management. J Endocr Soc. 2020;4(12):bvaa151. 7. Aljuraibah F, et al. An Expert Perspective on Phosphate Dysregulation With a Focus on Chronic Hypophosphatemia. J Bone Miner Res. 2022;37(1):12-20. 8. CRYSVITA (burosumab-twza). US Prescribing Information. Kyowa Kirin, Inc. March 2023.

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COMM-US-CRY-0076 | March 2025