Therapeutic Drug Monitoring for 5‑Fluorouracil
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Defines coverage stance for therapeutic drug monitoring (TDM) of intravenous 5‑fluorouracil (5‑FU) for dose adjustment and specifies tests that do not meet coverage. Applies to Healthfirst members whose benefits govern coverage at time of request.
No material clinical or coverage changes in this revision.
Coverage Criteria for 5‑FU Therapeutic Drug Monitoring
inv-01: Coverage — 5‑FU TDM
Covered when ALL of the following are met
Per policy, TDM to aid in managing dose adjustment MEETS COVERAGE CRITERIA
inv-02: Not covered tests — Not covered for dose adjustment
Not covered for dose adjustment
These tests DO NOT MEET COVERAGE CRITERIA due to lack of published evidence
Uracil breath tests and dihydrouracil/uracil ratio testing of plasma, serum, or urine are explicitly excluded from coverage when used to aid in managing dose adjustment for individuals undergoing 5‑fluorouracil chemotherapy. The policy states these tests "DO NOT MEET COVERAGE CRITERIA" due to lack of published evidence demonstrating they are required and beneficial for diagnosis or treatment.
The European Medicines Agency’s Pharmacovigilance Risk Assessment Committee (PRAC) concluded that DPD deficiency testing should be conducted before initiating fluoropyrimidine therapy and that the use of 5‑fluorouracil and related substances is contraindicated in patients with known complete DPD deficiency. PRAC also advised dose adjustments for patients with partial DPD deficiency.
Use of uracil breath tests or dihydrouracil/uracil ratio testing for guiding 5‑FU dose management is considered not meeting coverage criteria. The policy specifies these assays do not meet coverage for dose adjustment because available published scientific literature does not demonstrate they are required and beneficial for patient management.
The National Institute for Health and Care Excellence (NICE) reviewed the My5‑FU assay and recommended that it be used only for research purposes rather than routine clinical use, noting that the assay shows promise but is not currently endorsed for standard practice.
Applicable Codes and Coding Definitions
| No codes listed |
| S3722 | Dose optimization by area under the curve (AUC) analysis, for infusional 5-fluorouracil. |
| 80299 | Quantitation of therapeutic drug, not elsewhere specified. |
| 82542 | Column chromatography, includes mass spectrometry, if performed (e.g., HPLC, LC, LC/MS, LC/MS-MS, GC, GC/MS- MS, GC/MS, HPLC/MS), non-drug analyte(s) not elsewhere specified, qualitative or quantitative, each specimen. |
| 83789 | Mass spectrometry and tandem mass spectrometry (e.g., MS, MS/MS, MALDI, MS-TOF, QTOF), non-drug analyte(s) not elsewhere specified, qualitative or quantitative, each specimen. |
Provider Actions, Prior Authorization, and Documentation
Prior authorization coverage summary
Therapeutic drug monitoring (TDM) of intravenous 5‑fluorouracil (5‑FU) to aid dose adjustment meets Healthfirst coverage criteria for individuals undergoing 5‑FU chemotherapy. Uracil breath tests and dihydrouracil/uracil ratio testing do not meet coverage criteria for managing 5‑FU dose adjustment.
Verify prior authorization for TDM procedures
Procedure codes relevant to 5‑FU therapeutic drug monitoring are listed (S3722; 80299; 82542; 83789). Providers should verify prior authorization requirements and member plan benefits and confirm any Healthfirst coding edits before submitting claims.
Document indication for TDM
Ensure the clinical indication documents that the patient is receiving continuous intravenous 5‑FU and that TDM is being used to guide AUC-based dose adjustments, since coverage applies only when TDM is used to aid dose management.
Avoid non-covered assays for dose adjustment
Do not submit requests for uracil breath tests or dihydrouracil/uracil ratio testing when the intent is to guide 5‑FU dose adjustments; these tests do not meet coverage criteria and may be denied.
- Uracil breath tests
- Dihydrouracil/uracil ratio testing (plasma, serum, or urine)
Suggested documentation for IV 5‑FU TDM
For IV 5‑FU TDM, document that plasma 5‑FU was measured near the end of the infusion, state the rationale that AUC-based dosing is being used to guide dose adjustments, and record the intended target exposure (AUC 20–30 mg·h/L) and any assay-specific details used to calculate dose changes.
- Time specimen: plasma near end of infusion
- Rationale: TDM to guide AUC-based dosing adjustments
- Intended target AUC: 20–30 mg·h/L
- Proprietary assay details or limits of detection/quantitation when applicable
Coding and documentation expectations
Use the procedure codes listed (S3722; 80299; 82542; 83789) as general references and follow Healthfirst, CPT/HCPCS, and state/national coding and documentation rules; adherence to prior authorization and coding edits is required to avoid claim issues.
Non-covered assays for 5‑FU dose adjustment
Requests for uracil breath tests or dihydrouracil/uracil ratio testing to manage 5‑FU dose adjustments do not meet coverage criteria and are excluded from coverage.
- Uracil breath tests are not covered for dose adjustment
- Dihydrouracil/uracil ratio testing (plasma/serum/urine) is not covered for dose adjustment
Denial risk for improper coding or billing
Failure to follow proper coding, billing, and reimbursement guidelines (including Healthfirst claim edits and national coding standards) could result in denial or recoupment of payment.
- Adhere to NCCI, NCD/LCD, modifier, and other claim-edit rules
- Follow Healthfirst and state-specific coding and billing policies
Background and Rationale
5‑Fluorouracil (5‑FU) is commonly administered as a continuous intravenous infusion and exhibits substantial interpatient pharmacokinetic variability. Therapeutic drug monitoring (TDM) measuring plasma 5‑FU near the end of infusion is used to guide AUC‑based dosing, with a recommended target exposure of AUC 20–30 mg·h/L when applying pharmacokinetic dose optimization.
Definitions and Key Terms
Biomarker Requirements (DPD/DPYD and Uracil Levels)
Covered Regimens and Situations for AUC-Guided Monitoring
| Regimen / Setting | Typical administration | AUC target (mg·h/L) | Coverage status |
|---|---|---|---|
| Continuous intravenous 5‑fluorouracil for colorectal cancer (e.g., infusional regimens used in combination chemotherapy) | |||
| Continuous intravenous infusion (plasma sampling near end of infusion for TDM) | |||
| 20–30 | |||
| Covered when TDM is used to aid dose adjustment in individuals undergoing 5‑FU chemotherapy | |||
| Continuous intravenous 5‑fluorouracil for head-and-neck cancer (common infusional regimens) | |||
| Continuous intravenous infusion with AUC-guided sampling | |||
| 20–30 | |||
| Covered when TDM is used to aid dose adjustment in individuals undergoing 5‑FU chemotherapy | |||
| Continuous intravenous 5‑fluorouracil for other solid tumors treated with infusional 5‑FU (e.g., some gastric, anal, breast, skin cancers) | |||
| Continuous intravenous infusion; AUC monitoring applicable where protocols exist | |||
| 20–30 | |||
| Covered when TDM is used to aid dose adjustment in individuals undergoing 5‑FU chemotherapy |
| Guidance / Context | Recommended action when applying AUC-guided dosing | DPYD/DPD context | Coverage stance |
|---|---|---|---|
| IATDMCT: AUC is the accepted metric for assessing 5‑FU exposure; TDM reduces variability and toxicity and is strongly recommended for colorectal and head-and-neck cancer | |||
| Use plasma 5‑FU concentrations to guide dose titration toward target AUC (monitor near end of infusion and adjust dose to achieve AUC 20–30 mg·h/L) | |||
| DPYD genotype-guided recommendations: for intermediate metabolizers reduce starting dose and titrate using toxicity or TDM; for poor metabolizers avoid 5‑FU or use strongly reduced dose with early TDM if no alternative | |||
| Informational (policy supports TDM for dose adjustment; DPYD-guided use aligns with CPIC recommendations) | |||
| STP-PT / SFPT & GPCO: recommend implementation of 5‑FU TDM to ensure adequate exposure | |||
| Follow pharmacokinetic-guided dosing to increase proportion of patients within target AUC and reduce adverse effects; perform follow-up TDM after genotype-based dose reductions to avoid underdosing | |||
| Apply TDM particularly for partial DPD-deficient patients and when genotype indicates intermediate/poor metabolizer status | |||
| Informational (supports clinical use of AUC-guided TDM in specified contexts) |
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