Summary & Overview
CPT 80168: Ethosuximide Quantitative Assay
CPT code 80168 denotes a quantitative laboratory assay that measures ethosuximide levels in a patient specimen. Ethosuximide is an anticonvulsant used in seizure management, and accurate measurement supports therapeutic drug monitoring, toxicity assessment, and dose adjustment. This laboratory-based test is performed by trained analysts and is commonly ordered in clinical settings managing seizure disorders or suspected drug exposure.
Key payers addressed in the analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a national-level overview of the clinical role of the assay, payer coverage context, and typical sites where the service is delivered. The publication summarizes benchmarks for utilization and reimbursement where available, clarifies coding and billing considerations tied to the laboratory service, and outlines the clinical context that drives demand for the test, such as therapeutic drug monitoring and toxicity evaluation.
The report does not provide state-specific guidance; it presents national implications for laboratories, billing professionals, and clinicians regarding the use and billing of CPT code 80168. Data not available in the input will be noted where relevant.
Billing Code Overview
CPT code 80168 describes a quantitative laboratory assay for ethosuximide, an anticonvulsant medication. The service involves a laboratory analyst performing the technical procedures to analyze a specimen and determine the amount of ethosuximide present.
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Service type: Clinical toxicology/therapeutic drug monitoring laboratory test
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Typical site of service: Hospital laboratory, independent clinical laboratory, or outpatient diagnostic laboratory
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Clinical & Coding Specifications
Clinical Context
A 12-year-old patient with a history of absence seizures treated with ethosuximide presents for routine therapeutic drug monitoring after a recent dose adjustment. A clinician orders a quantitative serum ethosuximide assay to ensure therapeutic levels and assess adherence or potential toxicity. The patient arrives at an outpatient phlebotomy clinic in a hospital laboratory setting. A phlebotomist collects a blood specimen following facility protocol, labels and transports it to the chemistry/toxicology laboratory. A medical laboratory technologist or analyst performs the technical assay to quantitate serum ethosuximide (CPT 80168), documents analytic results in the laboratory information system, and releases quantitative values to the ordering clinician. Results are used by the neurologist or pediatrician to confirm therapeutic range, guide dosing, and evaluate for subtherapeutic levels or toxicity in the context of clinical signs such as increased seizure frequency or adverse effects.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | Default/No modifier | Standard reporting when no modifier applies |
26 |