Aetna modified CPB 0249 covering IBD serologic markers and thiopurine pharmacogenomic testing, effective September 26, 2025. Here's what billing teams need to know.
Aetna, a CVS Health company, updated its coverage policy for inflammatory bowel disease diagnostics under CPB 0249 Aetna. The policy governs medical necessity for TPMT and NUDT15 gene testing, thiopurine metabolite monitoring, fecal calprotectin (CPT 83993), and fecal lactoferrin (CPT 83630, 83631) — plus a long list of serologic markers Aetna will not cover. If your gastroenterology or lab billing team submits any of the covered CPT codes (81335, 82657, 84433, 0034U, 0169U, 0286U, 81401) or the not-covered codes, this update affects your claim denial rate and reimbursement.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | Aetna, a CVS Health company |
| Policy | Inflammatory Bowel Disease: Serologic Markers and Pharmacogenomic and Metabolic Assessment of Thiopurine Therapy |
| Policy Code | CPB 0249 |
| Change Type | Modified |
| Effective Date | September 26, 2025 |
| Impact Level | Medium |
| Specialties Affected | Gastroenterology, Clinical Laboratory, Pathology, Internal Medicine, Oncology (thiopurine use) |
| Key Action | Audit your IBD and thiopurine-related charge capture against the covered and not-covered code lists before September 26, 2025 |
Aetna IBD Thiopurine Testing Coverage Criteria and Medical Necessity Requirements 2025
The Aetna IBD coverage policy under CPB 0249 draws clear lines. Aetna covers five categories of testing. Everything else in the 30+ code list gets denied.
TPMT Testing Before Thiopurine Initiation
Aetna considers TPMT testing medically necessary before starting 6-mercaptopurine (6-MP) or azathioprine. You can bill either a genotypic assay (CPT 81335, 0034U, 0169U, 0286U, or 81401) or a phenotypic assay (CPT 82657 or 84433). One test per member per lifetime — that's the hard limit. Bill a second TPMT assay on the same member and you'll get a denial. There's no exception in the policy for repeat testing.
NUDT15 Gene Analysis
NUDT15 testing is covered as a separate, standalone indication. Aetna will reimburse NUDT15 gene analysis to identify members at risk of thiopurine-induced toxicity before starting azathioprine, mercaptopurine, or thioguanine. This applies to all three thiopurines — not just azathioprine and 6-MP. Several of the covered PLA codes (0034U, 0169U, 0286U) cover both TPMT and NUDT15 together, which can simplify billing.
Thiopurine Metabolite Monitoring
Aetna covers measurements of 6-thioguanine nucleotide (6-TGN) and 6-methylmercaptopurine nucleotide (6-MMPN) — the Prometheus Thiopurine Metabolites panel is cited by name. Two specific situations qualify: monitoring compliance in patients not responding to 6-MP or azathioprine, and assessing suspected toxicity. This isn't a routine monitoring benefit. The patient must be non-responsive or have a toxicity concern.
Fecal Calprotectin and Fecal Lactoferrin
Aetna covers fecal calprotectin (CPT 83993) for managing IBD — Crohn's disease and ulcerative colitis — and for distinguishing IBD from irritable bowel syndrome. Fecal lactoferrin (CPT 83630 qualitative, CPT 83631 quantitative) is covered specifically for distinguishing IBD from IBS. If you bill these for other indications, expect a denial.
The policy does not explicitly list prior authorization requirements within the CPB 0249 framework for these specific tests. That said, prior auth requirements can sit at the plan level rather than the policy level. Check plan-level benefits before billing, especially for the PLA codes (0034U, 0169U, 0286U), which routinely trigger prior auth at many payers.
Aetna IBD Serologic Marker Exclusions and Non-Covered Indications
This is where the policy gets expensive if you're not paying attention.
Aetna will not cover a long list of serologic and immunoassay tests under this CPB. These include ANCA antibodies (CPT 86036, 86037), anti-CdtB and anti-vinculin antibodies for IBS (CPT 0164U, 0176U), procalcitonin (CPT 84145), myeloperoxidase (CPT 83876), C-reactive protein (CPT 86140), endomysial antibody (CPT 86231), tissue transglutaminase (CPT 86364), gliadin antibody (CPT 86258), and the IBD mRNA gene expression profiling panel 0203U.
The chemiluminescent assay (CPT 82397), mass spectrometry for non-drug analytes (CPT 83789), and general immunoassay codes 83516, 83518, 83519, and 83520 are also not covered for the indications in this policy.
The real issue here is that some of these codes — particularly the immunoassay family (83516–83520) and ANCA antibodies — are commonly ordered alongside thiopurine monitoring or IBD workups. Clinicians may order them as part of a standard panel. But Aetna's billing guidelines under CPB 0249 reject them explicitly. Check your order sets and EHR IBD panels now. If any of these codes are bundled into a standard IBD workup at your facility, your billing team needs to know before September 26, 2025.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| TPMT genotypic testing before 6-MP or azathioprine | Covered | 81335, 0034U, 0169U, 0286U, 81401 | Once per lifetime per member |
| TPMT phenotypic/enzyme assay before 6-MP or azathioprine | Covered | 82657, 84433 | Once per lifetime per member; either genotypic OR phenotypic — not both |
| NUDT15 gene analysis before thiopurine therapy | Covered | 0034U, 0169U, 0286U, 81401 | Covers azathioprine, mercaptopurine, thioguanine |
| 6-TGN and 6-MMPN metabolite monitoring | Covered | (billed per lab CPT — not separately enumerated in policy) | Only for non-response or suspected toxicity — not routine monitoring |
| Fecal calprotectin for IBD management or IBD vs. IBS distinction | Covered | 83993 | Crohn's disease, ulcerative colitis |
| Fecal lactoferrin for IBD vs. IBS distinction | Covered | 83630, 83631 | Qualitative or quantitative |
| Anti-CdtB / anti-vinculin antibodies for IBS | Not Covered | 0164U, 0176U | Explicitly excluded under CPB 0249 |
| ANCA antibodies | Not Covered | 86036, 86037 | Not covered for IBD indications listed |
| Procalcitonin | Not Covered | 84145 | Not covered for indications in CPB 0249 |
| Myeloperoxidase | Not Covered | 83876 | Not covered for indications in CPB 0249 |
| IBD mRNA gene expression profiling (17-gene panel) | Not Covered | 0203U | Not covered for indications listed |
| Immunoassay codes (general) | Not Covered | 83516, 83518, 83519, 83520, 82397 | Not covered for CPB 0249 indications |
| C-reactive protein | Not Covered | 86140 | Not covered for CPB 0249 indications |
| Tissue transglutaminase | Not Covered | 86364 | Not covered for CPB 0249 indications |
| Endomysial antibody | Not Covered | 86231 | Not covered for CPB 0249 indications |
| Gliadin (deamidated) antibody | Not Covered | 86258 | Not covered for CPB 0249 indications |
| Mass spectrometry, non-drug analyte | Not Covered | 83789 | Not covered for CPB 0249 indications |
| Actin (smooth muscle) antibody | Not Covered | 86015 | Not covered for CPB 0249 indications |
| Aquaporin-4 antibody | Not Covered | 86051, 86052, 86053 | Not covered for CPB 0249 indications |
| Fluorescent noninfectious agent antibody | Not Covered | 86255, 86256 | Not covered for CPB 0249 indications |
| Voltage-gated calcium channel antibody | Not Covered | 86596 | Not covered for CPB 0249 indications |
| Fungal antibody NES | Not Covered | 86671 | Not covered for CPB 0249 indications |
| Immunofluorescence additional stain | Not Covered | 88350 | Not covered for CPB 0249 indications |
| Leukocyte/ANCA antibody identification | Not Covered | 86021 | Not covered for CPB 0249 indications |
Aetna IBD Thiopurine Testing Billing Guidelines and Action Items 2025
| # | Action Item |
|---|---|
| 1 | Audit your TPMT billing for duplicate lifetime claims. The one-per-lifetime rule for TPMT testing (genotypic or phenotypic) is a hard denial trigger. Before the effective date of September 26, 2025, pull claims history for members with TPMT testing under CPT 81335, 82657, 84433, 0034U, 0169U, or 0286U. Flag any member who has already had a TPMT assay billed — a second claim will deny. |
| 2 | Choose genotypic or phenotypic TPMT — not both. Aetna covers one assay per lifetime. If a provider orders both a genetic test (CPT 81335) and an enzyme assay (CPT 84433) at the same time or in the same episode, only one will get paid. Coordinate with your lab and ordering providers to pick the appropriate test type upfront. |
| 3 | Update your IBD order set and EHR panels. Remove or flag the not-covered codes before September 26, 2025. Specifically, check for CPT 86036, 86037, 84145, 83876, 86140, 0164U, 0176U, and 0203U in any standard IBD or GI workup panel. These generate denial exposure that's avoidable. |
| 4 | Tighten the documentation for 6-TGN / 6-MMPN monitoring. Aetna's medical necessity standard for thiopurine metabolite testing is narrow. The chart must document either non-response to 6-MP or azathioprine, or a suspected toxicity event. Routine monitoring without that documentation won't support medical necessity on audit. Brief your GI providers on what the notes need to say. |
| 5 | Verify plan-level prior auth requirements for PLA codes. The policy doesn't mandate prior authorization at the CPB level, but PLA codes like 0034U, 0169U, and 0286U frequently require prior auth at the plan level. Before billing these codes for Aetna members, confirm the specific plan's PA requirements. One undocumented prior auth turns a covered code into a denied claim. |
| 6 | Map your ICD-10 codes correctly. The covered indications require IBD diagnosis codes — Crohn's disease and ulcerative colitis diagnoses — or active thiopurine therapy. The policy's diagnosis code list includes infectious GI conditions (Salmonella, Shigella, amebic infections) as context codes for the IBS vs. IBD distinction use case. Make sure your fecal calprotectin (CPT 83993) and fecal lactoferrin (CPT 83630, 83631) claims tie to appropriate primary diagnoses. |
If your practice has a mixed payer population and high IBD volume, loop in your compliance officer before the effective date. The combination of the per-lifetime TPMT rule and the broad not-covered code list creates real audit exposure if your workflows aren't tight.
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for IBD Thiopurine Testing Under CPB 0249
Covered CPT Codes (When Selection Criteria Are Met)
| Code | Type | Description |
|---|---|---|
| 0034U | CPT (PLA) | TPMT and NUDT15 gene analysis (e.g., thiopurine metabolism) |
| 0169U | CPT (PLA) | NUDT15 and TPMT gene analysis (e.g., drug metabolism) |
| 0286U | CPT (PLA) | CEP72, NUDT15, and TPMT gene analysis |
| 81335 | CPT | TPMT gene analysis, common variants (e.g., *2, *3) |
| 81401 | CPT | Molecular pathology procedure, Level 5 |
| 82657 | CPT | Enzyme activity in blood cells/cultured cells/tissue, nonradioactive substrate |
| 83993 | CPT | Calprotectin, fecal |
| 84433 | CPT | Thiopurine S-methyltransferase (TPMT) |
| 83630 | CPT | Lactoferrin, fecal; qualitative |
| 83631 | CPT | Lactoferrin, fecal; quantitative |
Not Covered CPT Codes
| Code | Type | Description |
|---|---|---|
| 0164U | CPT (PLA) | IBS immunoassay for anti-CdtB and anti-vinculin antibodies |
| 0176U | CPT (PLA) | Cytolethal distending toxin B (CdtB) and vinculin IgG antibodies by ELISA |
| 0203U | CPT (PLA) | Autoimmune IBD mRNA gene expression profiling, 17 genes, quantitative RT-PCR |
| 82397 | CPT | Chemiluminescent assay |
| 83516 | CPT | Immunoassay for analyte other than infectious agent antibody or antigen, qualitative |
| 83518 | CPT | Immunoassay for analyte other than infectious agent antibody or antigen; qualitative |
| 83519 | CPT | Immunoassay, quantitative, by radioimmunoassay (RIA) |
| 83520 | CPT | Immunoassay, analyte, quantitative; not otherwise specified |
| 83789 | CPT | Mass spectrometry and tandem mass spectrometry, non-drug analyte |
| 83876 | CPT | Myeloperoxidase (MPO) |
| 84145 | CPT | Procalcitonin (PCT) |
| 86015 | CPT | Actin (smooth muscle) antibody (ASMA), each |
| 86021 | CPT | Antibody identification; leukocyte antibodies (ANCA antibodies) |
| 86036 | CPT | Antineutrophil cytoplasmic antibody (ANCA); screen, each antibody |
| 86037 | CPT | ANCA titer, each antibody |
| 86051 | CPT | Aquaporin-4 (NMO) antibody; ELISA |
| 86052 | CPT | Aquaporin-4 antibody; cell-based immunofluorescence assay (CBA) |
| 86053 | CPT | Aquaporin-4 antibody; flow cytometry (FACS) |
| 86140 | CPT | C-reactive protein |
| 86231 | CPT | Endomysial antibody (EMA), each immunoglobulin class |
| 86255 | CPT | Fluorescent noninfectious agent antibody; screen, each antibody |
| 86256 | CPT | Fluorescent noninfectious agent antibody; titer, each antibody |
| 86258 | CPT | Gliadin (deamidated) antibody, each immunoglobulin class |
| 86364 | CPT | Tissue transglutaminase, each immunoglobulin class |
| 86596 | CPT | Voltage-gated calcium channel antibody, each |
| 86671 | CPT | Antibody; fungus, not elsewhere specified |
| 88350 | CPT | Immunofluorescence, per specimen; each additional single antibody stain |
Key ICD-10-CM Diagnosis Codes
| Code | Description |
|---|---|
| A02.0 | Salmonella enteritis |
| A03.0–A03.9 | Shigellosis (multiple subcategories) |
| A04.0–A04.9 | Other bacterial intestinal infections |
| A06.0–A06.4 | Acute amebic dysentery, chronic intestinal amebiasis, amebic nondysenteric colitis, ameboma of intestine |
| A07.0–A07.9 | Other protozoal intestinal diseases |
| A08.0–A08.3 | Viral and other specified intestinal infections |
The full ICD-10-CM list under CPB 0249 includes 95 codes. The complete list — including Crohn's disease, ulcerative colitis, and IBS codes — is available in the full policy at app.payerpolicy.org/p/aetna/0249.
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