CPT code 82378 – Carcinoembryonic antigen billing guide

Key takeaways

CPT code 82378 reports a quantitative carcinoembryonic antigen (CEA) blood test, billed by the lab that performs it.

Medicare’s 2026 Clinical Laboratory Fee Schedule sets a national limit of $18.96 for 82378, the same as in 2025.

NCD 190.26 supports CEA for colorectal cancer follow-up at treatment decision points and as an alternative marker in some lung and GI cancers.

Screening diagnoses such as Z12.11 do not support medical necessity, so they are the quickest route to a denial.

The NCD limits routine testing to once per chemotherapy cycle, or every two months after colorectal surgery, unless results or symptoms change.

CPT code 82378 tracks CEA in patients with known cancer

CPT code 82378 reports a quantitative carcinoembryonic antigen (CEA) assay on serum. The American Medical Association places it in the Chemistry subsection of the Pathology and Laboratory section. The result is a number, usually in ng/mL, rather than a positive or negative reading.

CEA is a glycoprotein that rises in several cancers, most often colorectal cancer. Smoking and some benign conditions can raise it too, so the test does not diagnose cancer. Medicare pays for it to follow disease that is already known. That one distinction drives most of the billing rules below.

The lab bills 82378, and the practice bills the draw

Plenty of CEA billing errors start with confusion over who bills what. Under Medicare, the laboratory that performs the assay bills 82378. A practice that draws blood and ships it to a reference lab does not bill the test. Here is how a typical CEA claim moves:

1. Order: the treating provider orders CEA and records the cancer diagnosis and the reason for testing now.
2. Draw: whoever collects the sample bills 36415 for the venipuncture, which carries a 2026 national limit of $9.34.
3. Assay: the performing lab bills 82378 with the diagnosis from the order and the ordering provider’s NPI.
4. Adjudication: the payer checks the diagnosis against its covered list and the test date against frequency limits.
5. Remittance: payment or denial comes back on the electronic remittance advice, with reason codes on any denied line.

If your practice runs CEA in its own lab, you are the performing lab. You then bill 36415 and 82378 on the same claim, and your CLIA certificate must cover the test.

NCD 190.26 pays for CEA at treatment decision points

Medicare covers CEA testing under National Coverage Determination 190.26, which binds every Medicare Administrative Contractor (MAC). The NCD describes three situations where the test may be medically necessary:

• Colorectal cancer follow-up: testing at treatment decision-making points for patients with colorectal carcinoma.
• Alternative marker: monitoring lung adenocarcinoma, small cell lung cancer and some gastrointestinal cancers when the tumor expresses no more specific marker.
• Preoperative baseline: a CEA level before surgery, which helps assess whether the resection was adequate.

Frequency limits sit inside the NCD

The NCD also sets expected testing intervals. Check them before you schedule a repeat draw:

• No more than once per chemotherapy cycle for metastatic solid tumors that express CEA.
• No more than every two months after surgery for colorectal cancer.
• Usually once only for carcinoma in situ, unless that first result is abnormal.

A significant change in the prior CEA level, or in the patient’s condition, can justify testing sooner. Record that change in the order, because the claim alone will not show it. Your MAC may also publish local guidance, so check its articles too.

Screening falls outside the benefit

Medicare does not cover tests run without signs, symptoms, complaints or a personal history of disease. Screening codes such as Z12.11 are missing from the NCD’s covered list. Family history codes are listed as not supporting medical necessity. A personal history code is different, and Z85.038 is covered.

Before an order reaches billing, run it through the three checks below.

Covered diagnosis codes decide whether the claim pays

The diagnosis on the claim is what proves medical necessity. CMS updates the covered ICD-10-CM list for NCD 190.26 every quarter, and the table shows common pairings from the October 2026 list. Confirm current code status with the CDC/NCHS ICD-10-CM tool before you submit.

A patient still in treatment for rectal cancer is billed with C20 rather than a history code. Switch to a Z85 code once treatment has ended and the visit is for surveillance.

Breast cancer needs a closer look. C50 codes sit on the Medicare covered list, yet the NCD text names only colorectal, lung and some GI cancers. For breast and other solid tumors, commercial coverage depends on payer policy. Anthem’s CG-LAB-33, for example, lists metastatic breast cancer.

Medicare pays $18.96 for 82378 in 2026

CEA is paid under the Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule. CMS sets one national limit amount for each lab code, with no facility or non-facility split. The CMS Clinical Laboratory Fee Schedule files list the current figures each quarter.

Payment can land below the national limit, because Medicare pays the lower of the limit and your billed charge. Load the new figure into your fee schedule each January.

The order note has to carry the medical necessity

Billing staff never see the draw, so the ordering note is the claim’s only evidence. An auditor reviewing 82378 looks for four elements:

• Confirmed diagnosis: the cancer diagnosis or personal history code, stated in the note.
• Reason for testing now: for example, “two-month post-resection surveillance” or “restaging after cycle 4”.
• Treatment history: a short line on prior surgery, chemotherapy or radiation for this cancer.
• Next step: what the provider will do if CEA rises, such as imaging or an oncology referral.

A note that only says “check CEA” will not survive a medical necessity review. Sound medical billing compliance depends on the reason being written in the order, not inferred from older chart entries.

Modifiers rarely belong on an 82378 line

Most CEA claims go out with no modifier at all. When one applies, choose it from the scenario and record the reason in the note.

Payers audit modifiers 91 and 59 closely. Write the reason into the note before the claim goes out, not after a denial arrives.

Four tumor-marker codes get confused with 82378

Several tumor-marker codes sit close to 82378 in the lab section. Picking the wrong one changes the payment and invites a denial. The AAPC Codify CPT lookup confirms each descriptor.

When an oncologist orders CEA and CA 19-9 on the same day, report 82378 and 86301 on separate lines. Each needs its own supporting diagnosis, because neither code includes the other. The payment differs as well, since each look-alike code carries a 2026 national limit of $20.81.

Medicare Advantage and commercial plans add their own rules

Original Medicare does not require prior authorization for CEA monitoring when the diagnosis is covered. Other plans can be stricter, so check before the draw:

• Anthem: Medical Policy CG-LAB-33 sets clinical criteria for CEA testing. Review it before billing repeat tests for Anthem members.
• Other commercial payers: authorization rules vary by plan and region. Check the plan’s lab authorization list, not just the insurer’s general policy.
• Medicare Advantage: a plan may require prior authorization even when NCD 190.26 would cover the test under Original Medicare.

When a plan does require approval, send the diagnosis, treatment history, ordering note and planned testing schedule together. Our guide to the prior authorization process shows how to keep requests moving. An incomplete request can stall approval before a claim even exists.

Five denial triggers show up on 82378 claims

CEA denials follow a predictable pattern, and each trigger maps to a check you can run at order entry. Our guide to medical billing denial codes explains how each reason reads on the remittance.

On the remittance, CARC 50 (not medically necessary) and CARC 11 (diagnosis inconsistent with procedure) are the most common on 82378 claims. Good denial management treats these triggers as checks before submission. Fixing a denial after the fact costs more staff time than preventing it at order entry.

Run this checklist before you submit 82378

These checks take seconds once they live in a written checklist. Keep it next to your payer list and walk every CEA claim through it:

• The diagnosis appears on the current NCD 190.26 covered list, or in the payer’s policy.
• No screening or family history code is attached to the line.
• The last CEA date sits outside the NCD window, or the note records a significant change.
• The order note states the clinical reason for testing now.
• Prior authorization is confirmed for any plan that requires it.
• The CPT code matches the marker ordered, with 82378 used for CEA only.
• The draw is billed as 36415 by whoever collected the sample.
• The fee schedule shows the current CLFS amount.

A claim that clears every line goes out as a clean claim and skips a round of rework.

How Pabau supports clean CEA claims from record to remittance

Many practices still key lab charges and diagnoses into a billing system by hand. Each retyped code is another chance for a screening diagnosis or the wrong marker to reach the claim.

Pabau, the practice management and billing platform we build, pre-fills the claim from the patient record. The CPT code attached to the service lands on the charge line, and ICD-10 slots draw from the recorded problem list. Built-in ICD-10-CM and CPT lookup libraries let staff confirm a code without leaving the claim.

Before a claim can be sent, Pabau’s claims management software checks that required fields are complete. US claims go through Claim.MD, Pabau’s clearinghouse partner, which also runs real-time eligibility checks. It returns 835 remittance data for ERA posting, so CARC 50 and CARC 11 denials show up quickly.

Checks against NCD 190.26 and the frequency window stay with your team and the checklist above. Pabau removes the rekeying around them.

Send cleaner 82378 claims with less rekeying

Pabau pre-fills claims from the patient record, checks required fields before sending, and routes US claims through Claim.MD with ERA posting. Your team spends less time correcting lab claims.

Book a demo

Conclusion

CEA billing rewards discipline at the order, not effort at the appeal. Get the diagnosis, the reason for testing and the interval right, and 82378 pays its $18.96 national limit without a fight.

The trade-off is time spent up front. Every check in this article happens before the draw, when fixing an order takes a minute. After a denial, the same fix means a corrected claim, a resubmission and a wait.

If your team still rekeys lab charges between systems, remove that step first. Book a demo to see how Pabau carries codes from the patient record into a clean lab claim.

Continue your research

Need to see how clearinghouse submission works? Claim.MD clearinghouse guide explains how electronic claim routing and ERA posting cut manual reconciliation.

Want claim data structured before it reaches billing? Superbill guide shows how to capture codes and diagnoses at the visit, so fewer claims need correcting.

Looking for the full revenue cycle behind lab billing? Revenue cycle management fundamentals walks through the process from order entry to collected payment.

Coding a rectosigmoid tumor? ICD-10 code C19 covers a diagnosis that supports many CEA monitoring claims.

Following a patient after breast cancer treatment? ICD-10 code Z85.3 explains the personal history code for breast cancer.

Frequently asked questions