Summary & Overview
CPT 80161: Carbamazepine –10,11–epoxide Quantitative Assay
CPT code 80161 designates a quantitative laboratory assay for the –10,11–epoxide metabolite of carbamazepine in patient specimens such as serum. This metabolite testing supports clinical management by identifying elevated levels that may indicate toxicity from carbamazepine, an anticonvulsant used for epilepsy and some neurologic and psychiatric conditions. The code is relevant nationally to hospital and outpatient clinical laboratories, toxicology services, and clinicians who monitor therapeutic drug safety.
Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare and Medicare. Readers will find a concise clinical context for the assay, typical sites of service, common billing modifiers and payer coverage patterns where available. The publication summarizes billing and coding considerations, benchmarks for utilization, and policy or coverage updates that affect laboratory processing of antiepileptic drug metabolite testing. Clinical implications for monitoring carbamazepine toxicity and the role of quantitative metabolite measurement in medication safety are also presented.
Data not available in the input: associated taxonomies, ICD-10 diagnoses, related CPT codes, and specific payer policy language.
Billing Code Overview
CPT code 80161 describes a laboratory quantitative assay for the carbamazepine –10,11–epoxide metabolite performed by a lab analyst on a patient specimen such as serum. The test measures the metabolite level of carbamazepine, an anticonvulsant medication used to treat epilepsy and certain neurologic and psychiatric disorders. Measured metabolite concentrations can be used to monitor possible medication toxicity and guide clinical interpretation of carbamazepine therapy.
Service type: Clinical laboratory service — quantitative drug metabolite assay
Typical site of service: Clinical laboratory or hospital laboratory (ambulatory or inpatient specimen collection and processing)
Clinical & Coding Specifications
Clinical Context
A 42-year-old patient with a history of focal epilepsy treated with carbamazepine presents to an outpatient neurology clinic for routine follow-up and reports increased dizziness and gait instability. The treating neurologist suspects possible carbamazepine toxicity or altered metabolism and orders serum therapeutic drug monitoring, including quantification of the carbamazepine –10,11–epoxide metabolite. A phlebotomy technician draws a serum specimen at the clinic, which is sent to the hospital clinical laboratory. The laboratory analyst performs the technical assay to quantify the level of the –10,11–epoxide metabolite of carbamazepine using an appropriate validated method. Results are reported to the ordering neurologist and documented in the electronic health record. If the level indicates potential toxicity, the clinician may adjust medication dose or arrange urgent follow-up.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation component (if applicable when split billing applies). |
TC | Technical component | Use when billing only the technical component for the laboratory performing the assay. |