Summary & Overview
CPT 80170: Gentamicin Quantitative Assay
CPT code 80170 represents a quantitative laboratory assay for gentamicin, a commonly used aminoglycoside antibiotic. The test measures serum or plasma gentamicin concentration to support therapeutic drug monitoring, dosing adjustments, and toxicity avoidance. Nationally, therapeutic drug monitoring codes such as 80170 are important for inpatient and outpatient care where narrow therapeutic index antibiotics are used, and they intersect clinical decision-making, laboratory operations, and payer coverage policies.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of where this service is performed, the clinical rationale for measuring gentamicin levels, and the typical service line classification. The publication outlines benchmarks for clinical utilization and payer coverage patterns where available, summarizes relevant policy considerations affecting lab reimbursement and billing practices, and provides context for laboratory workflow and documentation expectations.
This summary is written for a national audience and is intended to inform clinical managers, laboratory directors, and revenue cycle professionals about the role and billing context of CPT code 80170 without making clinical recommendations.
Billing Code Overview
CPT code 80170 describes a laboratory analytical procedure in which a lab analyst measures the quantitative concentration of gentamicin, an aminoglycoside antibiotic, in a patient specimen. The service is a therapeutic drug monitoring laboratory assay used to determine serum or plasma levels of gentamicin to guide dosing and assess toxicity risk.
Service Type: Laboratory—Therapeutic Drug Monitoring (Quantitative Drug Assay)
Typical Site of Service: Clinical laboratory, hospital laboratory, or independent reference lab
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A hospitalized adult patient receiving intravenous gentamicin for severe gram-negative sepsis requires therapeutic drug monitoring. The clinical workflow begins when the treating physician orders a serum gentamicin level to ensure concentrations are therapeutic and to avoid nephrotoxicity or ototoxicity. A timed blood specimen is collected by nursing or phlebotomy (often a trough immediately before the next dose or a peak at a specified interval after infusion). The specimen is sent to the clinical laboratory. A medical technologist or lab analyst performs 80170 using validated quantitative methods (e.g., immunoassay or chromatography) to measure the gentamicin concentration. Results are reported in mg/L or µg/mL to the ordering clinician, documented in the electronic health record, and used to adjust dosing. Typical sites of service include hospital inpatient laboratories, outpatient hospital labs, and independent clinical laboratories that process therapeutic drug monitoring specimens. Common patient scenarios include critically ill patients in the intensive care unit, patients with renal impairment, neonates receiving aminoglycosides, and patients on prolonged gentamicin therapy requiring level monitoring.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | When billing only the physician interpretation component if applicable to associated tests that have separate professional components |