CPT 84450: Aspartate Aminotransferase (AST) Quantitative Assay

Headline: CPT code 84450: Quantitative AST (SGOT) laboratory assay — clinical and payer context

CPT code 84450 denotes a quantitative laboratory assay for aspartate aminotransferase (AST/SGOT), a widely used serum or plasma chemistry test that signals hepatocellular injury, muscle damage, and certain renal conditions. As a routine component of metabolic and hepatic panels, this test plays a key role in diagnosis, monitoring disease progression, and guiding treatment decisions across inpatient and outpatient settings.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of clinical indications and service settings, payer coverage considerations, commonly reported modifiers, and benchmarking context where available. The publication summarizes how CPT code 84450 fits into laboratory service lines, expected sites of service, and typical clinical scenarios prompting AST measurement.

This overview equips clinicians, billing professionals, and policy analysts with the essential coding and clinical context for CPT code 84450, clarifies what to expect from payer engagement, and outlines the types of administrative details and benchmarking topics addressed in the full publication.

Billing Code Overview

CPT code 84450 describes a laboratory chemistry procedure in which a lab analyst performs the technical assay to quantitate the enzyme aspartate aminotransferase (AST), also known as serum glutamic oxaloacetic transaminase (SGOT). The test is typically performed on serum or plasma using automated laboratory chemistry analyzers. Elevated AST levels are clinically important because they occur in conditions such as hepatitis, renal disease, and muscle disease.

Service Type: Clinical laboratory chemistry assay

Typical Site of Service: Clinical laboratory or hospital laboratory; outpatient phlebotomy and laboratory facilities

Clinical Context

A 52-year-old adult presents to an outpatient primary care clinic with new onset right upper quadrant abdominal discomfort and fatigue. The clinician suspects hepatocellular injury and orders laboratory evaluation including liver chemistry panels. A phlebotomy technician draws a serum sample, which is sent to the clinical laboratory. The laboratory analyst performs the quantitative enzymatic assay for aspartate aminotransferase using automated chemistry analyzers; the result helps distinguish hepatic from muscle sources of transaminase elevation and guides further testing (for example, alanine aminotransferase, alkaline phosphatase, bilirubin, and hepatitis serologies). Typical workflow steps include specimen collection in serum or plasma, accessioning, centrifugation, analyzer run, verification by a laboratory scientist, result entry into the electronic medical record, and communication to the ordering provider. Typical site of service is outpatient clinic or hospital laboratory (clinical laboratory/chemistry analyzer).

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when a physician interprets and reports testing elements requiring professional interpretation (rare for automated chemistry tests but applicable if professional oversight/reporting occurs).
`TC`

Taxonomy Code	Specialty	Notes
207Q00000X	Clinical Pathology	Laboratory directors and clinical chemists who oversee and validate chemistry assays.
207L00000X	Anatomic and Clinical Pathology	Pathologists who supervise clinical laboratory operations.
363LP0808X	Laboratory Technician	Phlebotomists and laboratory technologists performing the assay on chemistry analyzers.
391200000X	Family Medicine	Ordering clinicians in outpatient settings who commonly request AST testing.
208D00000X	Gastroenterology	Specialists who order and interpret liver enzyme testing in hepatobiliary disease.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`K75.9`	Inflammatory disease of liver, unspecified	AST is elevated in inflammatory hepatic conditions and helps assess disease activity.
`K74.60`	Unspecified cirrhosis of liver without ascites	Chronic liver disease often shows abnormal AST/ALT patterns used in monitoring.
`B19.10`	Hepatitis C without hepatic coma	Viral hepatitis commonly elevates AST; testing helps triage further virologic evaluation.
`B18.2`	Chronic viral hepatitis C	Chronic hepatitis causes persistent transaminase abnormalities monitored with AST.
`M60.9`	Myositis, unspecified	Muscle disease can raise AST; clinical correlation with muscle symptoms is necessary.
`N17.9`	Acute kidney failure, unspecified	AST can be abnormal in multisystem illness including renal disease; helps in broader metabolic assessment.
`R74.0`	Nonspecific elevation of levels of transaminase and lactic acid dehydrogenase	Directly describes the laboratory abnormality prompting AST measurement and follow-up.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`80053`	Comprehensive metabolic panel (CMP)	Often ordered with AST to evaluate overall metabolic and hepatic function; includes multiple chemistry tests that complement AST.
`82040`	Albumin; serum or plasma	Frequently paired with AST to assess synthetic liver function.
`84460`	Alanine aminotransferase (ALT) (SGPT)	Commonly ordered alongside AST to help differentiate liver from muscle injury and assess hepatocellular damage.
`86140`	Hepatitis B surface antigen	May be ordered following abnormal AST to evaluate for viral hepatitis as an etiology.
`80061`	Lipid panel	May be ordered in ambulatory workups where AST elevation could be related to metabolic syndrome or medication effects.

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Summary & Overview