Summary & Overview
CPT 81309: PIK3CA Gene Sequence Analysis, Technical Component
CPT code 81309 denotes molecular laboratory testing for sequence analysis of the PIK3CA gene. This code captures the technical component of laboratory work that identifies sequence variants in the phosphatidylinositol–4,5–biphosphate 3–kinase, catalytic subunit alpha gene, a test with growing relevance in oncology and targeted therapy selection. Nationally, accurate coding for PIK3CA sequencing affects coverage determinations, clinical reporting, and billing for precision medicine services.
Key payers discussed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise synopsis of what CPT code 81309 represents, typical sites of service, and the service type. The publication provides benchmarks and coding context relevant to molecular diagnostics, summarizes payer coverage considerations at a national level, and outlines clinical context for use of PIK3CA sequencing in diagnostic and therapeutic decision-making. Data not available in the input are explicitly noted where applicable.
Billing Code Overview
CPT code 81309 describes a laboratory test that analyzes specific gene sequences of the phosphatidylinositol–4,5–biphosphate 3–kinase, catalytic subunit alpha (PIK3CA) gene. The service involves technical laboratory analysis performed by a lab analyst to detect sequence variants in the PIK3CA gene.
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Service type: Molecular genetic testing (technical component)
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Typical site of service: Clinical diagnostic laboratory or pathology laboratory performing molecular diagnostics
Clinical & Coding Specifications
Clinical Context
A 58-year-old female with hormone receptor–positive, HER2-negative metastatic breast cancer undergoes targeted molecular testing to identify actionable somatic mutations. The oncology team orders PIK3CA gene sequencing to detect activating variants that may guide selection of PI3K inhibitors. A tumor specimen (formalin-fixed paraffin-embedded tissue) or a recent plasma sample for circulating tumor DNA is sent to a molecular pathology laboratory. The laboratory analyst performs the technical assay corresponding to 81309 to analyze specific PIK3CA gene sequences using validated next-generation sequencing (NGS) or allele-specific PCR methods. Results are reported to the ordering oncologist and entered into the electronic medical record; the professional component (interpretation) may be billed separately by a pathologist or molecular geneticist, while the technical component covers specimen processing, sequencing run, and raw data generation.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when a physician or qualified pathologist performs the interpretation/reporting separate from the lab technical work. |
TC |