Summary & Overview
CPT 80165: Free Valproic Acid Blood Level
CPT code 80165 represents a laboratory assay that measures the free (unbound) valproic acid level in a patient’s blood. Free valproic acid measurement is clinically important because only the unbound fraction is pharmacologically active and correlates with efficacy and toxicity risk in patients receiving valproic acid for seizure disorders. Nationally, this code matters for therapeutic drug monitoring protocols, clinical laboratory billing, and payer coverage determinations for patients on anticonvulsant therapy.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context for free valproic acid testing, typical sites of service, and the role of the assay in medication management. The publication outlines reimbursement and coding benchmarks where available, summarizes common modifier usage and billing considerations, and highlights policy and coverage trends relevant to laboratory therapeutic drug monitoring. Data not available in the input will be explicitly noted where applicable. The content is intended for billing professionals, laboratory managers, and clinicians seeking concise guidance on coding and clinical context for CPT code 80165.
Billing Code Overview
CPT code 80165 describes a laboratory measurement of free valproic acid concentration in blood. This test quantifies the unbound fraction of valproic acid, an anticonvulsant medication used to treat certain types of seizures, to assess therapeutic levels and potential toxicity.
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Service type: Therapeutic drug monitoring (laboratory assay)
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Typical site of service: Clinical laboratory or hospital laboratory setting
Clinical & Coding Specifications
Clinical Context
A 28-year-old woman with generalized tonic-clonic seizures managed on valproic acid presents for routine therapeutic drug monitoring because of breakthrough events and concerns about adverse effects. The provider orders a free valproic acid level to assess pharmacologically active (unbound) drug concentration due to hypoalbuminemia from recent pregnancy and suspected drug interactions. Blood is drawn in the outpatient lab; the specimen is handled by the laboratory phlebotomy team, sent to the chemistry/toxicology laboratory, and analyzed using an assay that separates free from protein-bound valproic acid. The laboratory analyst documents the 80165 test result in the electronic laboratory information system and releases the report to the ordering neurologist, who uses the free valproic acid concentration to interpret efficacy and toxicity and to guide dosing adjustments.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation component if the lab report includes a separately billable professional interpretation by a pathologist or laboratory director. |
TC |