Summary & Overview
HCPCS G6036: Assay of Imipramine
HCPCS Level II code G6036 denotes an assay for imipramine, a tricyclic antidepressant, used clinically for therapeutic drug monitoring and confirmation of medication adherence or toxicity risk. Nationally, standardized reporting of drug assays supports safe prescribing, dose adjustment, and detection of potentially toxic blood levels, making such codes relevant for clinical laboratories, payers, and clinicians managing mental health and pain therapies.
This analysis covers major national payers: Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for imipramine testing, standard sites where the assay is performed, and information useful for billing teams and laboratory managers. The publication summarizes available benchmarks and common billing practices where available, highlights relevant policy considerations for coverage and medical necessity, and frames how the test integrates into therapeutic drug monitoring workflows.
The report does not provide state-specific guidance. It aims to inform coding staff, laboratory directors, and revenue cycle professionals about the clinical purpose of G6036, typical service settings, and the payer landscape nationally, noting where input data was unavailable.
Billing Code Overview
HCPCS Level II code G6036 represents an assay of imipramine, a laboratory test that measures blood levels of the tricyclic antidepressant imipramine. The service type is therapeutic drug monitoring / clinical laboratory assay. The typical site of service for this assay is clinical laboratory or hospital laboratory.
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Clinical & Coding Specifications
Clinical Context
A typical patient is an adult receiving therapeutic drug monitoring for a tricyclic antidepressant. The patient presents to an outpatient laboratory or clinic for blood draw after several weeks of imipramine therapy for depression, neuropathic pain, or enuresis. The clinician orders an assay of imipramine to confirm therapeutic serum levels, assess adherence, evaluate suspected toxicity (anticholinergic effects, cardiac conduction changes), or guide dose adjustment when interacting medications or hepatic impairment are present. The workflow: clinician documents indication and orders the imipramine assay (G6036) in the electronic medical record, the patient has a venipuncture in the laboratory or clinic phlebotomy area (typical sites: outpatient laboratory, hospital outpatient department, or clinic), the specimen is processed and sent to the performing laboratory, and the testing laboratory reports quantitative serum concentration to the ordering clinician for interpretation and management.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
TC | Technical component | Use when billing only the technical component of the laboratory test (instrumentation, technician time, reagents) by the performing laboratory or facility. |