Summary & Overview

CPT 85379: D-dimer Measurement in Patient Plasma

CPT code 85379 represents a laboratory assay that measures D–dimer levels in patient plasma. D–dimer testing is widely used in clinical pathways for evaluating suspected thromboembolic events and for monitoring coagulation-related conditions. Nationally, this test is commonly ordered in emergency, inpatient, and outpatient settings to support decision-making about imaging, anticoagulation, and further diagnostic workups.

Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The summary covers how CPT code 85379 is billed across major payers, typical sites of service, and clinical contexts in which the test is ordered.

Readers will find: concise clinical context for the assay; payer coverage scope and billing considerations; common service locations and utilization drivers; and where data is unavailable, an explicit note that input information is not provided. Data not available in the input includes detailed payer-specific reimbursement rates, associated taxonomies, and ICD-10 diagnosis mappings.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 85379D-dimerLaboratoryHematologyDiagnostic TestingPlasma AssayClinical PathwayLab Billing

Billing Code Overview

CPT code 85379 describes a laboratory test in which a lab analyst measures the level of D–dimer in patient plasma. This test quantifies fibrin degradation products to help assess the presence of thrombotic activity.

Service type: Laboratory diagnostic testing using patient plasma
Typical site of service: Hospital laboratory, independent clinical laboratory, or outpatient laboratory collection site

Clinical & Coding Specifications

Clinical Context

A typical patient is an adult presenting to an emergency department or outpatient clinic with acute onset unilateral leg swelling, chest pain, shortness of breath, or unexplained tachycardia. The treating clinician orders a plasma D‑dimer test to help evaluate for suspected venous thromboembolism (deep vein thrombosis or pulmonary embolism) or to assist in excluding thrombotic disease in low‑to‑moderate pretest probability patients. Blood is drawn into appropriate anticoagulated tubes, transported to the clinical laboratory, and processed by a laboratory technologist or automated analyzer using CPT 85379 to measure D‑dimer concentration. Results are reported to the ordering clinician to support decisions about imaging (for example, compression venous ultrasound or CT pulmonary angiography) or anticoagulation management. Typical sites of service include the hospital clinical laboratory, outpatient laboratory, and emergency department. The typical specimen is patient plasma obtained from venipuncture and tested by a qualified laboratory analyst or technologist under standard laboratory protocols.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when reporting only the professional interpretation component if applicable to a complex lab service with separate professional reporting.
`59`	Distinct procedural service	Use when the D‑dimer test is performed and billed separately from another lab test or service on the same day that would otherwise be bundled.
`91`	Repeat clinical diagnostic laboratory test	Use when the exact same D‑dimer test is repeated on the same day to obtain a subsequent result.
`90`	Reference (outside) laboratory	Use when the specimen is sent to an outside reference laboratory for testing.
`52`	Reduced services	Use when the test is partially reduced or not performed to the full extent for documented reasons.
`53`	Discontinued procedure	Use when specimen collection or testing is discontinued after initiation for documented clinical reasons.
`QW`	CLIA waived test	Use when the D‑dimer assay performed is a CLIA‑waived method and payer requires this modifier.
`TC`	Technical component	Use when reporting only the technical component of the lab test (instrumentation, reagents, technician time) if separated from professional component.
`90`	Duplicate entry - already listed above	When used to indicate testing at a reference lab (see above).
`91`	Duplicate entry - already listed above	When used to indicate repeat test on same day (see above).

Taxonomy Code	Specialty	Notes
207R00000X	Pathology & Laboratory Medicine	Laboratory directors and pathologists overseeing testing and result validation.
363L00000X	Clinical Laboratory	Medical technologists and clinical laboratory scientists performing the assay.
207L00000X	Anatomic and Clinical Pathology	Physicians who may interpret complex coagulation profiles in conjunction with D‑dimer.
208D00000X	Emergency Medicine	Emergency physicians who order D‑dimer testing frequently for acute evaluations.
207K00000X	Hematology	Hematologists consulted for complex coagulation or thrombotic disorders.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`I82.401`	Acute embolism and thrombosis of unspecified deep veins of right lower extremity	D‑dimer is used to help evaluate suspected DVT in a patient with leg swelling or pain.
`I26.99`	Other pulmonary embolism without acute cor pulmonale	Elevated D‑dimer prompts imaging for pulmonary embolism evaluation.
`R06.02`	Shortness of breath	Non‑specific symptom that may prompt D‑dimer testing when PE is in differential.
`R22.42`	Localized swelling, mass and lump, lower limb	Limb swelling with concern for DVT where D‑dimer assists triage.
`R07.9`	Chest pain, unspecified	Chest pain with concern for pulmonary embolism may lead to D‑dimer testing.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`36415`	Collection of venous blood by venipuncture	Blood draw required to obtain plasma specimen for the `CPT 85379` D‑dimer assay.
`71260`	CT angiography, chest, for pulmonary embolus protocol	Imaging often performed after an elevated D‑dimer to confirm pulmonary embolism.
`93970`	Duplex scan of extremity veins (non‑vascular clinical) complete bilateral study	Ultrasound used to evaluate suspected deep vein thrombosis when D‑dimer is positive or clinical probability is moderate/high.
`85610`	Prothrombin time; not otherwise specified	Common coagulation test performed alongside D‑dimer in patients with suspected thrombotic or bleeding disorders.
`85730`	Thrombin time	Additional coagulation testing sometimes ordered in complex hemostasis evaluations following abnormal D‑dimer results.