Serum Testing for Evidence of Mild Traumatic Brain Injury
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Defines Capital Bluecross coverage stance on serum (and related fluid) biomarker testing for evaluation of mild traumatic brain injury (mTBI), including specific biomarkers and panels, and summarizes scientific background and guideline context affecting reimbursement decisions.
No material clinical or coverage changes in this revision.
Coverage Criteria and Rationale
Primary coverage rules
Covered when ALL of the following are met:
External guidance and regulatory context
Summary of external guideline positions and regulatory context referenced in this policy:
ALL of the following
Guideline positions
- CDC: advises that biomarkers should not be used outside research settings for diagnosis of children with mTBI due to insufficient evidence.
- VA/DoD: suggests against using serum biomarkers to establish diagnosis of mTBI or to direct care for identified patients, excluding those with indicators for immediate referral.
- American Medical Society for Sports Medicine: notes fluid biomarkers are under investigation, evidence level is low, and biomarkers have no established role in diagnosis or management of sports-related concussion.
- American Academy of Pediatrics: acknowledges multiple biomarkers have been investigated but none are used in clinical settings for children.
- Professional society conditional guidance: American College of Surgeons: indicates GFAP, UCH-L1, and S100B can be used to help rule out need for CT in certain adults (GCS 13-15) meeting clinical criteria and assessed as low but nonzero risk.
- Regulatory notes: FDA: has cleared/approved specific assays (Abbott i-STAT TBI Plasma Cartridge with i-STAT Alinity System and Abbott Alinity i TBI lab test) intended for adults ≥18 within 12 hours of injury to aid decisions about radiologic imaging; LDTs are regulated under CLIA as high-complexity tests and are not FDA-cleared/approved.
Evidence and guideline references
Selected evidence and guideline sources cited in the policy (representative list):
ALL of the following
Key trials and diagnostic studies
- Papa et al., Journal of Neurotrauma 2014: GFAP outperforms S100B in detecting traumatic intracranial lesions on CT in trauma patients with mTBI.
- Welch et al., Journal of Neurotrauma 2016: assessed ability of GFAP, UCH-L1, and S100B to differentiate normal and abnormal head CT findings in suspected mild/moderate TBI.
- Korley et al., The Lancet Neurology 2022 (TRACK-TBI cohort): prognostic value of day-of-injury plasma GFAP and UCH-L1 for predicting functional recovery after TBI.
- Gan et al., Front Neurol 2019: quantitative assessment of diagnostic and prognostic accuracy of blood biomarkers for TBI.
Guidelines and policy sources
- ACEP/Annals of Emergency Medicine: clinical policy on neuroimaging and decisionmaking in adult mTBI (Valente et al., 2023).
- CDC: Mild TBI Management Guideline (2018) and related CDC pediatric guideline (Lumba-Brown et al., JAMA Pediatr 2018).
- VA/DoD clinical practice guidelines for management of post-acute mTBI (Version 3.0, 2021).
- American College of Surgeons best practices guidance on use of GFAP, UCH-L1, and S100B to help rule out CT in select adults.
Covered indications
Statement of covered indications in this portion of the policy:
Intended Uses and Evaluations Discussed
FDA-cleared intended use population/time window
FDA-cleared/approved intended-use population and time window for specified assays referenced in the policy:
Evaluation contexts
Clinical contexts in which biomarkers have been evaluated in the cited literature:
ANY of the following
- Evaluation of suspected mild or moderate traumatic brain injury to detect intracranial lesions visible on head CT (diagnostic use).
- Prognostic assessment of functional recovery and outcome after TBI (prognostic use).
- Adjunct to clinical decision rules to help determine need for CT in adults assessed as low but nonzero risk (per American College of Surgeons guidance).
Not Covered / Exclusions
Measurement of concussion markers and related biomarker panels for evaluation of mild traumatic brain injury does not meet coverage criteria. Specifically, testing for serum, saliva, or cerebrospinal fluid concentrations of biomarkers such as S100B, GFAP, and UCH-L1, as well as panels designed to measure these markers (for example, i-STAT TBI Plasma and Alinity® i TBI), are stated in the policy as not meeting coverage criteria due to insufficient published evidence that these tests are required and beneficial for diagnosis or treatment.
The policy notes that multiple professional organizations and guideline sources discourage routine clinical use of fluid biomarkers for concussion in certain populations, particularly children. The CDC and other organizations state that biomarkers should not be used outside research settings for diagnosis of pediatric mTBI, and societies including the VA/DoD and sports medicine groups recommend against using these serum biomarkers to establish diagnosis or direct care in routine practice.
Within the referenced sections of the document there are no additional explicit exclusions beyond the general noncoverage statements. The evidence citations and references summarize published studies of GFAP, UCH-L1, and S100B but do not list specific procedural or population exclusions that would alter the policy’s overall not covered stance.
Provider Guidance and Billing Notes
Coverage denial — concussion biomarkers and panels discouraged
Measurement of concussion markers (for example S100B, GFAP, and UCH-L1) in blood, saliva, and/or cerebrospinal fluid does not meet coverage criteria; panels designed to measure biomarkers of TBI (for example i-STAT TBI Plasma and Alinity® i TBI) also do not meet coverage criteria.
Billing codes referenced for TBI biomarker testing
Procedure codes referenced for serum biomarker testing include general immunoassay (83516), an unlisted chemistry code for GFAP analysis (84999), and a PLA code for combined GFAP+UCH-L1 assay reporting (0570U).
- 83516 — Immunoassay for analyte other than infectious agent antibody or antigen; qualitative or semiquantitative, multiple step method.
- 84999 — Unlisted chemistry procedure (Neurology (traumatic brain injury), analysis of glial fibrillary acidic protein (GFAP)).
- 0570U — Analysis of GFAP and UCH-L1, immunoassay, whole blood or plasma; individual components reported with overall elevated/non-elevated result.
Regulatory / test availability — examples of FDA-cleared assays
FDA-cleared/approved tests are available: the Abbott i-STAT TBI Plasma Cartridge for the i-STAT™ Alinity™ System and Abbott's Alinity® i TBI lab test are described with their intended uses.
- i-STAT TBI Plasma Cartridge (i-STAT™ Alinity™ System): FDA 510(k) cleared Jan 8, 2021; intended to aid evaluation of patients 18 years or older with suspected mTBI (GCS 13–15) within 12 hours of injury to assess need for radiologic imaging.
- Alinity® i TBI lab test: FDA approved March 2023 as a lab-based test measuring UCH-L1 and GFAP; runs on Abbott's Alinity® i instrument.
Regulatory context — clearance does not equal coverage
FDA clearance or approval of lab-based and handheld blood tests is noted in the document, but regulatory clearance does not by itself imply that these tests meet Capital Bluecross coverage criteria.
- The policy states LDTs are regulated under CLIA as high-complexity tests and are not FDA-cleared/approved; FDA clearance/approval was granted for specific Abbott assays but the policy separately states these tests do not meet coverage criteria.
- FDA 510(k) clearance (Abbott handheld test) and lab-based clearance are described as regulatory events, not coverage determinations.
Ordering requirements — no provider/order restrictions specified
No explicit ordering or ordering-provider requirements are specified in this portion of the policy; coverage determination depends on the individual's benefit coverage at the time of the request.
- The policy indicates application of coverage criteria is dependent upon an individual's benefit coverage and refers to 'Applicable State and Federal Regulations' for Medicare/Medicaid specifics.
Ordering context — intended-use population noted; provider specifics not defined
FDA-authorized assays are described with intended use for adults meeting clinical criteria (for example adults ≥18 with suspected mTBI, GCS 13–15, within 12 hours of injury), but the policy text does not define which provider types may order these tests.
- Intended-use population and time window are specified for the i-STAT/Alinity tests (adults ≥18, GCS 13–15, within 12 hours) but the document does not specify ordering provider qualifications.
- Guideline statements (e.g., American College of Surgeons) describe clinical scenarios for use yet do not create explicit ordering rules in the policy text.
Ordering requirements — no direct administrative rules specified
No additional ordering steps, prior-authorization requirements, or provider documentation specifications are given in these sections; guideline citations may inform clinical use but do not establish direct administrative rules in the policy.
- Guidelines from ACEP, CDC, VA/DoD, AAP and others are cited and may inform clinical decision-making, but the policy does not set explicit ordering rules based on those guidelines in the cited sections.
- Laboratory-developed tests (LDTs) are discussed as CLIA-regulated high-complexity tests, but specific ordering or administrative requirements are not specified here.
Procedure and Billing Codes
| No codes listed |
| 83516 | Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; qualitative or semiquantitative, multiple step method |
| 84999 | Unlisted chemistry procedure Neurology (traumatic brain injury), analysis of glial fibrillary acidic protein (GFAP) |
| 0570U | Neurology (traumatic brain injury), analysis of glial fibrillary acidic protein (GFAP) and ubiquitin carboxylterminal hydrolase L1 (UCHL1), immunoassay, whole blood or plasma, individual components reported with the overall result of elevated or non-elevated based on threshold comparison |
| No codes listed |
Terminology and Biomarker Definitions
Ordering and Provider Notes
Ordering requirements — coverage reliant on individual benefits
No ordering/provider requirements are specified in this portion of the policy; coverage decisions depend on the individual's benefit coverage at the time of the request.
- Verify member benefit coverage prior to ordering these tests.
Ordering requirements — intended-use population stated; ordering provider not specified
FDA-authorized assays are described as intended for adults (≥18) with suspected mTBI meeting clinical criteria within 12 hours of injury; the policy does not specify which provider types may order the assays.
- Intended use: adults 18 years or older with suspected mTBI (GCS 13–15) within 12 hours of injury to aid decision about imaging.
Ordering requirements — guidelines referenced but no explicit ordering rules provided
Guideline citations (ACEP, CDC, VA/DoD, AAP and others) are included and may inform who should order testing in clinical practice, but the policy text does not provide explicit ordering rules.
- Professional society recommendations are summarized elsewhere in the document but do not create explicit administrative ordering requirements in these sections.
Frequency and Limits
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