CPT 84145: Procalcitonin (PCT) Level Assay

CPT code 84145 reports a laboratory assay to quantify procalcitonin (PCT) in a patient specimen, typically serum. Procalcitonin measurement has national clinical relevance as a biomarker used to support evaluation of systemic bacterial infection and sepsis, inform clinical decision-making, and guide antimicrobial stewardship programs. The code is billed for laboratory services performed in clinical and hospital laboratories and is relevant across inpatient, emergency department, and outpatient settings. Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise outline of what CPT code 84145 represents, the typical sites of service, common billing modifiers and service-line context when available, and where to locate related documentation. The publication provides national benchmarks and payer coverage context where available, summarizes relevant clinical indications for the test, and flags policy or coding updates affecting laboratory reporting. Data not available in the input is noted where applicable.

Billing Code Overview

CPT code 84145 describes a laboratory assay performed by a lab analyst to measure procalcitonin (PCT) levels in a patient specimen, commonly serum. The test is used to evaluate circulating levels of procalcitonin, a biomarker that can assist clinicians in the assessment of systemic bacterial infection and sepsis risk.

Service Type

Laboratory test

Typical Site of Service

Clinical laboratory or hospital laboratory; specimens are usually collected in an outpatient clinic, emergency department, or inpatient setting and sent to a certified clinical laboratory for analysis.

Clinical Context

A typical scenario involves an adult patient in the emergency department or inpatient setting who presents with suspected sepsis, severe systemic infection, or an acute bacterial infection where rapid differentiation between bacterial and non-bacterial causes is clinically important. The provider orders a procalcitonin test to assess the level of procalcitonin (PCT) in serum to help guide antimicrobial decisions and assess severity. Blood is drawn by phlebotomy; the specimen is delivered to the hospital laboratory or a reference lab. A medical technologist or laboratory analyst performs the 84145 assay (quantitative procalcitonin) using an automated immunoassay platform. Results are reported in ng/mL and interpreted by the ordering clinician in conjunction with clinical assessment and other laboratory data (CBC, blood cultures, lactate). Typical sites of service include the hospital inpatient laboratory, emergency department, and hospital outpatient laboratory. The workflow includes specimen collection, labeling, transport, accessioning, testing, quality control, result verification, and result reporting into the electronic health record for clinician review.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional component for interpretation or oversight if split billing applies.

Taxonomy Code	Specialty	Notes
207RH0000X	Clinical Pathology	Pathologists and clinical laboratorians who supervise and interpret complex laboratory testing.
207K00000X	Pathology	Anatomic and clinical pathologists overseeing laboratory operations and results verification.
364SP0800X	Medical Technologist	Medical technologists/clinical laboratory scientists performing the assay and running quality controls.
208000000X	Emergency Medicine	Emergency physicians who commonly order procalcitonin in sepsis evaluation and antimicrobial decisions.
207Q00000X	Internal Medicine	Hospitalists and internists who order and interpret procalcitonin for inpatient infection management.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`A41.9`	Sepsis, unspecified organism	Procalcitonin is frequently used to evaluate suspected sepsis and monitor response to therapy.
`R65.20`	Severe sepsis without septic shock	Elevated `PCT` supports diagnosis and helps gauge severity in systemic infections.
`R65.21`	Severe sepsis with septic shock	High `PCT` levels correlate with severe bacterial infection and worse prognosis.
`J18.9`	Pneumonia, unspecified organism	Procalcitonin assists in distinguishing bacterial pneumonia from viral or noninfectious causes.
`N39.0`	Urinary tract infection, site not specified	Used when systemic signs suggest urosepsis or complicated UTI requiring evaluation.
`A49.9`	Bacterial infection, unspecified	General bacterial infections where `PCT` may help determine antibiotic need.
`B95.9`	Streptococcal or staphylococcal infection as the cause of disease, unspecified	Organism-specific codes commonly sought in conjunction with cultures when `PCT` is elevated.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`36415`	Collection of venous blood by venipuncture	Usually performed immediately prior to `84145` to obtain the serum specimen for procalcitonin testing.
`82652`	C-reactive protein (CRP), quantitative	Often ordered alongside procalcitonin to assess systemic inflammation and help distinguish bacterial infection.
`87040`	Culture, bacterial; blood, aerobic and anaerobic bottles (set)	Blood cultures are commonly obtained concurrently to identify causative organisms when procalcitonin suggests bacterial sepsis.
`84443`	Assay of thyroid stimulating hormone (TSH)	An example of another quantitative serum assay commonly run in the same laboratory batch or panel workflows.
`87491`	Influenza, rapid amplified probe technique	Viral testing that may be ordered in parallel to procalcitonin to identify viral etiologies when infection source is uncertain.

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Summary & Overview