Authorization and medical necessity requirement

Services must meet authorization and medical necessity guidelines; immune cell function assays are explicitly stated as not meeting criteria for any situation and authorization is not supported for these tests.

• Explicit policy: “For all situations, an immune cell function assay (e.g., Pleximmune™, Pleximark™) DOES NOT MEET CRITERIA.”

Prior authorization may be required for listed procedure codes

Claims for listed procedure codes (e.g., 0018M, 86352) may require prior authorization per payer rules and must also comply with any applicable government coverage determinations.

• Codes referenced in this policy include 0018M and 86352 and may be subject to prior authorization.
• When government (LCD/NCD or state Medicaid) coverage applies, those policies must be followed.

Include test name and performing laboratory on orders/claims

When ordering or requesting testing, include the specific test name and laboratory performing the assay on the order and claim to ensure accurate processing and review.

• Policy notes that many labs have developed LDTs and that proprietary tests (e.g., ImmuKnow, Pleximmune) have specific regulatory/status distinctions.
• Use the procedure codes listed in the policy when billing proprietary assays (see CPT/HCPCS section).

Follow recommended stepwise diagnostic testing before advanced functional assays

Follow guideline-recommended diagnostic sequencing for suspected primary immunodeficiency: begin with immunoglobulin measurement and flow cytometry (T-cell enumeration and naive subset analysis), reserving in vitro proliferative or other advanced functional tests only if abnormalities on initial screening indicate the need.

• AAAAI/ACAAI: measure serum immunoglobulins and use lymphocyte proliferation and flow cytometry as indicated; flow cytometry is the screening test to enumerate CD4/CD8 and NK cells.
• ESID: diagnostic approach begins with TREC screening then flow-cytometric enumeration; qualitative immune function assays are of limited value and unreliable in lymphopenic patients.

Documentation and industry-standard coding required

Submit accurate clinical documentation of services performed and code claims according to industry-standard coding guidelines; failure to follow coding/billing guidelines may result in claim denial or recoupment.

• Policy requires coding consistent with CPT, HCPCS, ICD-10, UB, CMS NCCI, and other standard coding resources.
• Providers are responsible for documentation of services performed for review and reimbursement.

Include test name/lab and use the policy-listed procedure codes on claims

Identify the specific test (proprietary name when applicable) and include the listed procedure code(s) on the claim: e.g., use 0018M for Pleximark/Pleximmune variants and 86352 for cellular function assays involving stimulation and ATP or similar biomarkers.

• Policy lists 0018M for Pleximark/Pleximmune proprietary assays and 86352 for cellular function assays.
• When ordering proprietary assays, indicate the test name and laboratory to align with billing codes.

Denial risk for immune cell function assays (ICFAs)

Tests identified as immune cell function assays (examples: Pleximmune™, Pleximark™, ImmuKnow®, iQue®) do not meet coverage criteria and may trigger claim denial or prepayment review if submitted.

• Policy statement: immune cell function assays “DOES NOT MEET CRITERIA” for all situations.
• Proprietary assays are listed in the CPT/HCPCS section, and submission of these codes may prompt denial consistent with the non-coverage stance.

Applicable government coverage determinations govern when in conflict

If a relevant government policy (LCD/NCD or state Medicaid) conflicts with this policy, the government policy governs the coverage determination and must be followed; failure to follow applicable government coverage may result in denial.

• The policy disclaimer states government policies supersede this policy when there is a conflict and provides CMS links for current Medicare/Medicaid coverage.