CurrentAvMedPolicy N/A

Prior authorization criteria for Burosumab (Crysvita) for X-linked Hypophosphatemia (XLH) and Tumor-induced Osteomalacia (TIO)

Authorization form and medical necessity criteria for Crysvita (burosumab-twza) for treatment of X-linked hypophosphatemia (XLH) and FGF23-related tumor-induced osteomalacia (TIO); governs providers seeking coverage from AvMed.

Policy Summary

PayerAvMed

PolicyPrior authorization criteria for Burosumab (Crysvita) for XLH and TIO

Policy CodePolicy N/A

Change TypeNo material changes

Effective DateN/A

Next Review DateN/A

Key ActionComplete the medical prior authorization form and submit required clinical documentation (labs, imaging, biopsy, chart notes) to support each checked clinical criterion.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

6 monthsInitial authorization duration

6 monthsReauthorization interval

eGFR <30Renal exclusion

FGF23 ≥100TIO diagnostic threshold

FGF23 >30XLH diagnostic threshold

Policy Summary

PayerAvMed

PolicyPrior authorization criteria for Burosumab (Crysvita) for XLH and TIO

Policy CodePolicy N/A

Change TypeNo material changes

Effective DateN/A

Next Review DateN/A

Key ActionComplete the medical prior authorization form and submit required clinical documentation (labs, imaging, biopsy, chart notes) to support each checked clinical criterion.

SourceLink

On This Page

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Initial authorization — X-linked Hypophosphatemia (XLH)

Covered when ALL of the following are met:

Age and prescriber: Member is at least 6 months of age; prescribed by or in consultation with a nephrologist, endocrinologist, or specialist experienced in the treatment of metabolic bone disorders

Diagnosis confirmation: Documented diagnosis of X-linked hypophosphatemia (XLH) (submit chart notes and labs)

Diagnosis confirmed by at least ONE of: serum FGF23 > 30 pg/mL OR PHEX gene mutation; submit supporting test results

Clinical baseline data: Provider must submit progress notes documenting skeletal deformities, number of fractures, and generalized bone pain score

Submit chart notes documenting each item

Growth plate / prior therapy: Either: epiphyseal plates have NOT fused and member has tried and failed or is intolerant to calcitriol plus oral phosphate for ≥ 2 months (failure defined as abnormal phosphate despite compliance; submit chart notes), OR epiphyseal plates have fused and member is experiencing clinical signs/symptoms (e.g., limited mobility, musculoskeletal pain, bone fractures)

Failure defined as abnormal phosphate despite compliance with calcitriol plus oral phosphate for at least 2 months

Baseline labs and concurrent therapy: Baseline fasting serum phosphorus obtained within the last 30 days demonstrates hypophosphatemia (below laboratory age-specific lower limit); member has NOT received oral phosphate and/or active vitamin D analogs within 1 week prior to start

Submit current labs showing phosphate level

Renal function: Member does NOT have severe renal impairment (eGFR < 30 mL/min/1.73 m2)eGFR >= 30

Initial authorization — Tumor-induced osteomalacia (TIO)

Covered when ALL of the following are met:

Age and prescriber: Member is at least 2 years of age; prescribed by or in consultation with an oncologist, endocrinologist, or specialist experienced in the treatment of tumor-induced osteomalacia (TIO)

Tumor and diagnosis confirmation: Diagnosis of FGF23-related hypophosphatemia in TIO associated with phosphaturic mesenchymal tumor (PMT) that cannot be curatively resected or localized (must submit chart notes documenting reason surgery cannot be performed)

Tumor biopsy results OR whole-body functional imaging with follow-up CT/MRI/US must be submitted

Biochemical confirmation: Serum FGF23 (or iFGF23) ≥ 100 pg/mL (Kainos assay); other causes of FGF23 elevation (e.g., XLH, AD/AR hypophosphatemic rickets, Fanconi syndrome) have been ruled outFGF23 >= 100 pg/mL

Submit FGF23 assay result

Reauthorization — XLH and TIO

Covered when ALL of the following are met:

Continued diagnosis: Member continues to have the diagnosis for which burosumab was approved

Prior treatment: Member has previously received burosumab

Biochemical response: Member has experienced normalization of serum phosphate while on therapy (submit current labs)

Submit current labs demonstrating normalization

Clinical response: Provider chart notes confirm positive clinical response to burosumab (e.g., enhanced height velocity, improvement/healing of bone lesions, reduction of fractures, reduction of generalized bone pain)

Submit chart notes documenting clinical improvement

Crysvita will be discontinued if the member undergoes additional treatment of the underlying tumor, such as radiation therapy or surgical excision. If therapy is re‑initiated after such tumor-directed treatment, the Crysvita dose will be adjusted based on serum phosphate levels measured after the treatment is completed.

Use of burosumab is not appropriate for members with severe renal impairment. Severe renal impairment is defined as an estimated glomerular filtration rate of eGFR < 30 mL/min/1.73 m2; requests for members meeting this threshold do not meet medical necessity criteria.

Coding, Age & Diagnostic Thresholds

Covered HCPCS CodeHCPCSCovered

J0584

Burosumab-twza injection

Age thresholds — XLH and TIO

XLH minimum ageAt least 6 months of age

TIO minimum ageAt least 2 years of age

Prescriber requirementPrescribed by or in consultation with appropriate specialist (nephrologist/endocrinologist for XLH; oncologist/endocrinologist for TIO)

FGF23 diagnostic thresholds

XLH FGF23 thresholdSerum FGF23 level > 30 pg/mL

TIO FGF23 threshold (Kainos assay)Serum FGF23 (or iFGF23) ≥ 100 pg/mL by Kainos assay

Genetic confirmation (XLH)PHEX gene mutation may confirm diagnosis as alternative to FGF23

Renal function exclusion

Renal function exclusionSevere renal impairment defined as eGFR < 30 mL/min/1.73 m2 — use is not appropriate

Reauthorization noteReauthorization requires current labs and documentation; ensure eGFR remains ≥ 30 mL/min/1.73 m2

Baseline requirementBaseline fasting serum phosphorus and renal function must be submitted within 30 days

Prior Authorization, Documentation & Submission Requirements

Prior Authorization

Prior Authorization Required

Prior Authorization Required for Crysvita (burosumab-twza, J0584). Complete and sign the Medical Prior Authorization/Step-Edit Request form and fax to 1-877-535-1391. Requests with incomplete, incorrect, or illegible information (including missing phone/fax) may be delayed or denied.

Drug: Crysvita (burosumab-twza) Injection (J0584)
Fax: 1-877-535-1391
Prescriber signature required (preprinted stamps not valid)

Documentation Required

Required Form Fields

Required form fields must be completed to avoid delay or denial. The prescriber must sign and clearly print their name. Include full member and prescriber contact information, dosing and weight details, diagnosis with ICD code, date weight obtained, and requested length of therapy.

Member name, AvMed ID, date of birth
Prescriber name, NPI, prescriber signature, date
Office contact name, phone number, fax number
Drug name/form/strength, dosing schedule, length of therapy, weight and date weight obtained
Diagnosis and ICD code

Step Therapy

Step Therapy Requirement

Step therapy requirements apply for XLH and TIO indications. Prior to approval, members must have tried and failed (or have documented intolerance) to calcitriol combined with an oral phosphate agent as defined on the form; failure is abnormal phosphate levels despite at least 2 months of compliant therapy. For pediatric patients with unfused epiphyseal plates this is required; adults must also meet related clinical criteria.

Step therapy: trial of calcitriol + oral phosphate (e.g., K-Phos Neutra, phospho-trin 250) for ≥2 months unless intolerant (e.g., anaphylaxis)
Failure defined as persistent abnormal phosphate despite compliance
Pediatric XLH: required if epiphyseal plates not fused; alternatives/exceptions documented for intolerance

Documentation Required

Clinical Supporting Documentation Required

Submit supporting clinical documentation with the PA form. Include baseline and follow-up labs (fasting serum phosphorus within 30 days showing hypophosphatemia, serum FGF23 when applicable), genetic testing or biopsy/imaging results, chart notes documenting diagnosis, prior therapies and response, and objective measures of clinical status.

Baseline fasting serum phosphorus (within 30 days) and subsequent phosphate levels while on therapy
Serum FGF23 level and/or genetic testing (PHEX mutations) for XLH; FGF23 ≥100 pg/mL or iFGF23 ≥100 pg/mL and tumor localization/biopsy for TIO
Bone biopsy OV/BV and osteoid thickness when performed (TIO)
Chart notes documenting skeletal deformities, fractures, pain score, prior therapy trials and intolerances
Documentation of eGFR to exclude severe renal impairment (eGFR <30 mL/min/1.73 m2)

Background on Burosumab (Crysvita)

Burosumab (Crysvita) is indicated for treatment of hypophosphatemia due to X-linked hypophosphatemia (XLH) and for FGF23-related hypophosphatemia in tumor-induced osteomalacia (TIO). For both indications, authorization requires documentation of biochemical hypophosphatemia (baseline fasting serum phosphorus within 30 days), prior trial and failure or intolerance to combined calcitriol plus oral phosphate for at least 2 months, and absence of severe renal impairment. For TIO specifically, a baseline bone biopsy with osteoid volume/bone volume (OV/BV) and osteoid thickness results and confirmation that the tumor cannot be curatively resected or localized must be submitted; Crysvita may be discontinued if the member subsequently receives tumor-directed treatments such as surgery or radiation, with dosing adjustments at re-initiation guided by phosphate levels.

OpenPayer

Prior authorization criteria for Burosumab (Crysvita) for X-linked Hypophosphatemia (XLH) and Tumor-induced Osteomalacia (TIO)

Coverage Criteria for Burosumab (Crysvita)

Coding, Age & Diagnostic Thresholds

Prior Authorization, Documentation & Submission Requirements

Background on Burosumab (Crysvita)

Diagnostic Criteria and Definitions