Crysvita (burosumab-twza) — Coverage Criteria for X-linked hypophosphatemia (XLH) and FGF23-related hypophosphatemia in TIO
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This policy governs medical necessity criteria, prior authorization, and coding for Crysvita (burosumab-twza) for treatment of X-linked hypophosphatemia (XLH) and FGF23-related hypophosphatemia in tumor-induced osteomalacia (TIO) for applicable UnitedHealthcare commercial and individual exchange plans.
Policy transferred to shared template and applied to UnitedHealthcare Commercial and Individual Exchange plans; prior authorization requirements follow the member-specific plan.
No material clinical or coverage changes beyond template update were identified in this revision.
Coverage Criteria for Crysvita (burosumab-twza)
Initial Therapy (XLH)
Covered when ALL of the following are met for initial XLH therapy
From policy initial therapy section
Continuation Therapy (XLH)
Covered when ALL of the following are met for continuation (XLH)
From policy continuation section
Initial Therapy (TIO)
Covered when ALL of the following are met for initial TIO therapy
From policy TIO initial therapy section
Continuation Therapy (TIO)
Covered when ALL of the following are met for continuation (TIO)
From policy TIO continuation section
This policy summarizes the clinical coverage framework for Crysvita (burosumab-twza) in FGF23-mediated hypophosphatemic disorders. It defines the medical necessity expectations for initial and continuation therapy in X-linked hypophosphatemia (XLH) and for initial and continuation therapy in tumor‑induced osteomalacia (TIO). The policy aligns coverage determinations with documented diagnosis, age thresholds, biochemical data, prescriber specialty involvement, and dosing consistent with the FDA label. References to member-specific benefit plan terms, federal or state mandates, and Medicare program requirements are incorporated where applicable.
FDA approval and the drug’s labeled indications are provided here for informational context only. FDA approval alone is not a basis for coverage; coverage decisions require that the member’s clinical presentation and submitted documentation meet the policy’s medical necessity criteria and any applicable member benefit or regulatory requirements.
Coverage decisions under this policy depend on the documentation supplied and the member’s specific benefit terms. Providers must submit the clinical records and laboratory data specified in the coverage criteria; requests lacking the required diagnostic confirmation, relevant labs, or documentation of prior therapy where required may be denied. The inclusion of procedure or diagnosis codes in this policy is for reference only and does not guarantee coverage or payment—always verify the member’s benefit document and any applicable state mandates before assuming coverage.
Coding and Billing Codes
| J0584 | Injection, burosumab-twza, 1 mg |
| E83.31 | Familial hypophosphatemia |
| M83.8 | Other adult osteomalacia |
Provider Actions, Prior Authorization, and Documentation
Prior Authorization Required
Prior authorization is required for initiation of burosumab (Crysvita). Initial and reauthorization approvals are limited to no more than 12 months.
- Initial authorization: ≤ 12 months
- Reauthorization: ≤ 12 months
- Dosing must follow FDA labeling
Medicare Part B and CMS Compliance
For Medicare Advantage reviews, ensure compliance with Medicare Part B/NCDs/LCDs/LCAs where applicable. Part B rules (including "incident to" requirements and whether a drug is usually self‑administered) may affect coverage. Preferred therapy criteria may be governed by Medicare Part B step therapy programs — consult CMS guidance and the Medicare Advantage Medical Policy as needed.
- Check CMS NCDs/LCDs/LCAs: https://www.cms.gov/medicare-coverage-database/new-search/search.aspx
- Refer to Medicare Benefit Policy Manual, Chapter 15, §50
Required Clinical Documentation
Submit documentation that confirms the diagnosis, relevant labs, prior therapies, prescriber specialty, and age as applicable. Missing required documentation may lead to denial.
- Diagnosis confirmation: genetic testing showing PHEX mutation OR elevated serum FGF23 > 30 pg/mL OR biochemical profile (serum phosphate < 3.0 mg/dL; serum creatinine below age‑adjusted ULN; serum 25(OH)D ≥ 16 ng/mL)
- Prescriber: prescribed by or in consultation with an endocrinologist, oncologist, or specialist experienced in metabolic bone disorders (per indication)
- Laboratory data: fasting serum phosphorus below age‑specific normal range; serum creatinine and 25(OH)D levels as above
- Age: patient age ≥ 2 years for TIO indication
- Clinical response for continuation: documentation of positive clinical response (e.g., improved height velocity, improved skeletal deformities, fewer fractures, reduced generalized bone pain)
Member‑Specific Benefit Verification
Verify member benefits and any applicable federal or state mandates before authorizing therapy. The member specific benefit plan document governs and may impose different coverage terms.
- Confirm coverage under the member's specific plan documents
- Check for state or federal mandates that may affect coverage
- This policy assists interpretation of UnitedHealthcare standard benefit plans but the member specific benefit plan controls
Step Therapy Requirement for TIO
For tumor‑induced osteomalacia (TIO), document failure, contraindication, or intolerance to combination therapy with a vitamin D analog (e.g., calcitriol, paricalcitol, doxercalciferol) plus an oral phosphate agent (e.g., K‑Phos®, K‑Phos Neutra®) prior to initiating burosumab.
- Record prior use and outcome of vitamin D analog + oral phosphate therapy
- If contraindication or intolerance is cited, provide supporting clinical rationale and documentation
- For Medicare reviews, refer to CMS/Medicare Part B step therapy guidance as applicable
Background and Clinical Context
X-linked hypophosphatemia (XLH) is a heritable renal phosphate‑wasting disorder caused by elevated FGF23, resulting in chronic hypophosphatemia and impaired bone mineralization. The therapeutic mechanism of burosumab is neutralization of excess FGF23 to increase renal phosphate reabsorption and raise serum phosphate toward age‑appropriate ranges. In children the treatment goal focuses on correction of rickets and improved growth velocity; in adults the focus is on reducing bone pain, improving mobility, and promoting fracture or pseudofracture healing. For tumor‑induced osteomalacia (TIO), burosumab is used when the phosphaturic tumor cannot be localized or curatively resected and the patient has FGF23‑mediated hypophosphatemia.
Definitions
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