Quick Explanation
Denial code ON25 indicates that the frequency of tumor marker testing billed exceeds the established coverage guidelines or frequency limits set by the payer for a given timeframe. Payers restrict how often these diagnostic laboratory tests can be performed to monitor cancer unless there is documented clinical justification for more frequent evaluation. To secure reimbursement, providers must demonstrate that the additional tests were medically necessary due to changes in the patient's clinical status.
Common Causes for ON25
Denials with code ON25 typically happen for the following specific reasons:
- Ordering serial tumor marker tests (such as CEA, CA-125, or CA 19-9) more frequently than the standard National Coverage Determination (NCD) or Local Coverage Determination (LCD) allowed intervals.
- Failing to append appropriate modifiers, such as Modifier 91 (repeat clinical diagnostic laboratory test), when a duplicate test was clinically required on the same date of service.
- Submitting claims with non-specific diagnosis codes that do not support the active treatment or monitoring of a malignancy requiring high-frequency testing.
- Lack of coordination between multiple treating oncologists or specialists, resulting in overlapping orders for the same tumor marker within a short timeframe.
How to Prevent ON25 Denials
To avoid receiving this denial in the future, implement these specific checks:
- Implement clinical decision support alerts within the EHR and Laboratory Information System (LIS) to flag tumor marker orders that exceed payer-defined frequency thresholds.
- Conduct regular audits against CMS NCD guidelines (e.g., NCD 190.26 for CEA, NCD 190.28 for CA 125) to ensure internal scheduling aligns with frequency limitations.
- Secure a signed Advance Beneficiary Notice of Noncoverage (ABN) or commercial equivalent when tumor marker testing is ordered outside standard frequency limits to protect reimbursement.
- Ensure documentation explicitly details the acute clinical indications, such as change in treatment regimen or suspected recurrence, that warrant more frequent testing prior to claim submission.
Appeal Letter Template for ON25
If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.
[Your Practice Header]
[Date]
[Payer Name]
[Appeals Department Address]
RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: ON25 - Tumor marker testing frequency excessive
Dear Appeals Department,
I am writing to appeal the denial of the above-referenced claim, which was denied with code ON25: "Tumor marker testing frequency excessive".
We are appealing the denial of the tumor marker testing billed under CPT code [Insert CPT Code] for date of service [Insert Date of Service] based on denial code ON25. Pursuant to CMS National Coverage Determinations (NCDs) and AMA billing guidelines, standard frequency limitations for diagnostic laboratory tests may be exceeded when additional testing is medically necessary to manage a patient's active treatment. In this specific case, the patient was experiencing [Insert clinical reason, e.g., symptoms of rapid disease progression, initiation of a new line of chemotherapy, or suspicion of tumor recurrence], which required immediate monitoring to assess the efficacy of the therapeutic intervention. The attached clinical documentation clearly supports the medical necessity of this test outside of standard frequency parameters. Consequently, we respectfully request that you review the enclosed medical record and reverse this denial to process the claim for payment.
Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].
We respectfully request that you reprocess this claim for payment.
Sincerely,
[Your Name]
[Title]
[Practice Name]
Stop Writing Appeals Manually
Clausea can read your medical records and generate custom, evidence-based appeals for denial code ON25 in seconds.
Generate Appeal for ON25 Now