Summary & Overview
CPT 0404U: DiviTum®TKa Serum Thymidine Kinase Activity Assay
Headline: New PLA Code 0404U Captures DiviTum®TKa Serum Immunoassay to Monitor Proliferation in Metastatic HR+ Breast Cancer
Lead: CPT code 0404U designates a proprietary serum immunoassay, DiviTum®TKa (Biovica Inc.), that quantifies thymidine kinase activity to monitor cell proliferation and assess treatment effectiveness for female patients with metastatic hormone receptor–positive breast cancer. The code formalizes billing for a single-manufacturer laboratory test with algorithmic result interpretation.
Why it matters: PLA status makes 0404U specific to one commercial test, which affects coding clarity, payer policy development, and claims processing for precision monitoring in oncology. National payers are increasingly evaluating such assays for clinical utility in guiding systemic therapy decisions and monitoring response.
Payers covered: Analysis considers major national payers including Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
What readers will learn: The publication summarizes the clinical scope of CPT code 0404U, describes the service type and typical sites of service, and provides benchmarks and policy context relevant to proprietary oncology monitoring assays. It outlines expected documentation elements, payer coverage considerations, and where to find procedural clarity for billing a PLA test tied to a single manufacturer. Regulatory and reimbursement trend discussion focuses on how PLA coding influences payer review pathways and laboratory adoption nationally.
Billing Code Overview
CPT code 0404U is a Proprietary Laboratory Analyses (PLA) code for the DiviTum®TKa assay by Biovica Inc. The test is a serum-based immunoassay that measures thymidine kinase activity (TKa) to monitor cell proliferation in female patients with metastatic hormone receptor–positive breast cancer. Results are produced using an algorithmic analysis that can assist in evaluating treatment effectiveness.
Service type: Laboratory — Proprietary molecular/biochemical assay
Typical site of service: Clinical laboratory or hospital outpatient laboratory using a serum specimen
Data not available in the input for associated taxonomies, ICD-10 diagnoses, related codes, and service line.
Clinical & Coding Specifications
Clinical Context
A 62-year-old woman with metastatic hormone receptor–positive (estrogen and/or progesterone receptor positive), HER2-negative breast cancer is undergoing systemic endocrine therapy with or without targeted agents. The treating oncologist orders the DiviTum® TKa test (0404U) using a serum specimen to measure thymidine kinase activity as a biomarker of tumor cell proliferation. Blood draw for the serum assay is typically performed at the outpatient oncology clinic or an ambulatory phlebotomy site on the day of a routine clinic visit or at a laboratory collection center. The specimen is sent to the manufacturer-designated laboratory or reference lab performing the proprietary immunoassay. Results are received electronically and used by the oncologist to monitor treatment response and inform discussions about ongoing systemic therapy effectiveness during follow-up visits. Typical workflow steps: 1) order placed in the electronic medical record for 0404U; 2) outpatient phlebotomy collects a serum specimen following standard venipuncture; 3) specimen is labeled, processed, and shipped per lab instructions to the performing laboratory; 4) laboratory performs the immunoassay and algorithmic analysis; 5) result report is returned to the ordering clinician and documented in the medical record; 6) clinician reviews results with the patient to assess proliferation trends and treatment effectiveness.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 |