Therapeutic Drug Monitoring for 5-Fluorouracil
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Defines Oscar Health's coverage stance and clinical background for therapeutic drug monitoring (TDM) of intravenous 5-FU, including which TDM methods meet criteria and which do not, for providers submitting authorizations and claims.
No material clinical or coverage changes in this revision.
Coverage Criteria — When 5‑FU TDM Meets Criteria
Indications That Meet Criteria
Covered when ALL of the following are met
Applies to individuals receiving intravenous 5-FU infusion; target AUC guidance provided elsewhere in the policy.
Tests That Do Not Meet Criteria
Not covered when the test is the following
Listed explicitly as not meeting criteria due to insufficient published scientific literature.
Listed explicitly as not meeting criteria due to insufficient published scientific literature.
Uracil breath tests and dihydrouracil/uracil ratio testing of plasma, serum, or urine are explicitly listed as methods that do not meet criteria for aiding dose adjustment of 5‑fluorouracil (5‑FU) chemotherapy due to insufficient published evidence supporting their clinical benefit.
Regulatory guidance from the European Medicines Agency (EMA) pharmacovigilance committee (PRAC) concludes that systemic 5‑FU and related substances are contraindicated in patients with known complete DPD (DPYD) deficiency; PRAC also recommends DPD deficiency testing prior to treatment and dose adjustment for partial deficiency.
Within the cited reference sections of this document there are no additional explicit coverage exclusions beyond the tests and contraindications already described in the policy; the evidence sections list bibliographic references rather than new exclusion statements.
Use of uracil breath tests or dihydrouracil/uracil ratio testing to guide 5‑FU dosing is considered not meeting criteria (not medically necessary) because the policy states these specific methods lack sufficient published scientific literature to demonstrate they are required and beneficial for patient management.
The National Institute for Health and Care Excellence (NICE) has stated that the proprietary My5‑FU assay shows promise but should be used only for research purposes and is not recommended for routine clinical use.
No explicit additional statements labeling tests as 'not medically necessary' are present in the referenced evidence sections; those sections are bibliographic citations supporting the policy rather than standalone coverage determinations.
Coding — Procedure & Laboratory Codes
| 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 (eg, 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 (eg, MS, MS/MS, MALDI, MS‑TOF, QTOF), non‑drug analyte(s) not elsewhere specified, qualitative or quantitative, each specimen. |
Provider Actions — Authorization, Documentation, and Billing
Prior authorization / coverage stance for 5‑FU TDM
Therapeutic drug monitoring (TDM) to aid dose adjustment for individuals undergoing intravenous 5‑fluorouracil chemotherapy meets the policy's coverage criteria; conversely, uracil breath tests and dihydrouracil/uracil ratio testing do not meet criteria and are excluded.
- Meets criteria: TDM for individuals receiving 5‑FU infusion to manage dose adjustment.
- Does not meet criteria: Uracil breath tests and dihydrouracil/uracil ratio testing of plasma, serum, or urine.
Procedure codes to use for prior authorization and claims
List the applicable procedure codes when requesting authorization or submitting claims for 5‑FU TDM: S3722, 80299, 82542, and 83789 are provided by the policy as the relevant CPT/HCPCS procedure codes for AUC dose‑optimization and associated laboratory quantitation.
No separate prior‑authorization procedure detailed in this section
The policy text includes no separate, explicit prior authorization program requirements in these sections; it provides coverage determinations and coding guidance but does not specify unique prior authorization steps beyond standard payer rules.
- No additional prior‑authorization-specific instructions are stated in the Indications/Limitations sections.
- Follow standard Oscar prior authorization processes if applicable per member benefit and payer rules.
Follow CPIC genotype‑guided dosing with follow‑up TDM
CPIC recommends genotype‑guided starting dose reductions for DPYD variant carriers and advises follow‑up therapeutic drug monitoring (if available) to titrate dosing, which should be followed in clinical management.
- For DPYD intermediate metabolizers: reduce starting dose based on activity score and follow with toxicity‑based titration or TDM if available.
- For DPYD poor metabolizers: avoid 5‑FU where possible; if used, administer a strongly reduced starting dose with early TDM.
Required documentation and coding accuracy
Providers must submit accurate documentation of services performed and code claims according to industry standard coding guidelines; failure to follow coding/billing guidance may result in claim denial or recoupment.
- Document the procedure performed, test method, and clinical indication in the medical record.
- Code claims per CPT/HCPCS, ICD‑10, NDC, and other applicable coding manuals and payer rules.
Documentation expectation for LDTs and CLIA validation
Clinical laboratories performing 5‑FU TDM commonly use laboratory‑developed tests (LDTs) that must be validated and performed in‑house under CLIA high‑complexity rules; documentation of CLIA validation and test method may be expected by the payer.
- LDTs are regulated under CLIA '88 as high‑complexity tests and are not FDA‑cleared/approved.
- Be prepared to provide evidence of laboratory validation and CLIA certification if requested.
Denial risk: coding and documentation noncompliance
Claims may be denied or recouped if coding/billing guidelines or current reimbursement policies are not followed; ensure adherence to billing rules and accurate submission.
- Follow Uniform Billing Editor, AMA CPT guidance, HCPCS, ICD‑10, and CMS coding manuals.
- Noncompliance with coding/billing guidance can lead to denial or payment recoupment.
Coverage determinations must defer to applicable governmental policies
When there is a conflict between this policy and any applicable governmental policy (e.g., LCDs, NCDs, or state Medicaid rules), coverage determinations must defer to the governmental policy; failure to follow applicable government policy may affect coverage.
- Check relevant Medicare (LCD/NCD) and state Medicaid policies for the member before authorization or billing.
- Government policy supersedes this payer policy where conflicts exist.
No additional explicit authorization or denial criteria in evidence section
This section contains only evidence references and does not provide additional explicit authorization or denial criteria beyond the coverage determinations already stated (TDM meets criteria; specified uracil‑based tests do not).
- No separate authorization/denial decision rules are defined in the Evidence References section.
- Use the Indications/Limitations (III) and coding sections for operational authorization decisions.
Initial Therapy — Genotype and TDM Integration
Genotype‑guided initial dosing and TDM
Per CPIC: for DPYD intermediate metabolizers reduce starting dose based on activity score and titrate by toxicity or TDM; for DPYD poor metabolizers avoid 5-FU if possible, but if no alternatives, use a strongly reduced starting dose with early TDM.
Site of Care — Where TDM Is Performed
Site‑of‑care action: collect plasma near end of 5‑FU infusion for TDM assays
TDM described in this policy applies to patients receiving 5‑FU via intravenous infusion; plasma sampling is performed near the end of the infusion cycle for assays used to calculate AUC and guide dosing.
- Intended for patients receiving 5‑FU through intravenous infusion; plasma taken near end of infusion for assay.
- My5‑FU and similar proprietary tests use plasma AUC calculations to guide subsequent dosing.
Arrange sample collection and lab processing with CLIA‑certified high‑complexity labs
TDM assays are typically performed by CLIA‑certified high‑complexity laboratories; sample collection may occur in outpatient infusion centers, hospital outpatient departments, or offices according to lab workflow and clinical needs.
- LDTs are regulated under CLIA as high‑complexity tests and are performed in‑house by qualified labs.
- Sample collection for these assays commonly occurs in infusion centers or other outpatient settings.
Definitions & Abbreviations
Background — Clinical Rationale for 5‑FU TDM
5‑Fluorouracil (5‑FU) is an intravenously infused chemotherapeutic agent with a narrow therapeutic index. Although body surface area (BSA) dosing is common, the policy recognizes therapeutic drug monitoring (TDM) using AUC‑targeted dosing — with an accepted target range of 20–30 mg·h/L — as a clinically relevant approach to individualize dosing and reduce toxicity for patients receiving IV 5‑FU.
Revision History & Governance
Policy became effective for therapeutic drug monitoring of intravenous 5‑fluorouracil (5‑FU).
Clinical evidence, coding, and references were reviewed and documented (last review date recorded).
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