Summary & Overview
CPT 0604U: Bradykinin Quantitative Assay by LC–MS/MS
CPT code 0604U is a Proprietary Laboratory Analyses (PLA) code that identifies a single, manufacturer-specific laboratory test: quantitative measurement of four bradykinin peptides in whole blood by liquid chromatography–tandem mass spectrometry (LC–MS/MS) from Virant Diagnostics Inc. The assay has clinical relevance for evaluating disorders such as chronic recurrent angioedema where bradykinin pathways are implicated. Nationally, PLA codes like 0604U matter because they permit distinct identification of novel or proprietary assays for coverage, claims processing, and utilization tracking.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise review of the clinical context for the assay, the service setting and specimen type, and the implications of a PLA-designated CPT code for payer recognition and coding precision. The publication covers expected benchmarks for coding and billing adoption, potential policy considerations around proprietary diagnostics, and how the code fits into laboratory service lines and clinical workflows. Data not available in the input for payer-specific coverage policies, modifiers, taxonomies, ICD-10 pairings, or related codes is explicitly noted as unavailable, and readers will be directed to payer policies for specific coverage rules.
Billing Code Overview
CPT code 0604U is a Proprietary Laboratory Analyses (PLA) code that applies exclusively to a single laboratory test: Bradykinin, Quantitative, by LC–MS/MS from Virant Diagnostics Inc. The test quantitatively measures four bradykinin peptides in whole blood using liquid chromatography with tandem mass spectrometry (LC–MS/MS). Results support clinical assessment of disorders such as chronic recurrent angioedema.
Service Type: Proprietary laboratory molecular diagnostic test (PLA)
Typical Site of Service: Clinical laboratory or reference laboratory; specimen collected in an outpatient or inpatient setting as appropriate for laboratory testing.
Clinical & Coding Specifications
Clinical Context
A 38-year-old patient presents to an allergy/immunology clinic with a history of recurrent, nonpruritic angioedema episodes affecting the face and extremities over several months. Routine allergy testing and C1 esterase inhibitor studies were inconclusive. The treating allergist orders a specialized biochemical assay to quantify circulating bradykinin peptides to evaluate for bradykinin-mediated angioedema. A whole blood specimen is collected in the outpatient clinic and sent to Virant Diagnostics Inc. for the proprietary test reported with 0604U (Bradykinin, Quantitative, by LC–MS/MS). The laboratory performs liquid chromatography–tandem mass spectrometry analysis of four bradykinin peptides and returns a numeric report with peptide concentrations and interpretive comments. Results are reviewed by the ordering clinician to support diagnosis of chronic recurrent angioedema subtypes and guide further management decisions, such as considering targeted therapies or referral to specialized clinics. Typical site of service is outpatient clinic or outpatient phlebotomy with testing performed at the reference laboratory (Virant Diagnostics Inc.).
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use if reporting a separate professional component for test interpretation when applicable (rare for proprietary reference lab tests performed entirely by the laboratory). |
59 | Distinct procedural service | Use if reporting a separate service on the same day that is distinct and not incidental to the lab test (typically not appended to PLA lab codes but may apply to associated specimen collection services).
91 | Repeat clinical diagnostic laboratory test | Use when a medically necessary repeat of the same bradykinin quantitative test is performed on a separate specimen or to confirm abnormal results.
24 | Unrelated E/M service by the same physician during a postoperative period | Use if the ordering clinician provides an unrelated evaluation and management service on the same day as the test order during a global period.
25 | Significant, separately identifiable E/M service on the same day | Use when the clinician performs and documents a significant, separate evaluation unrelated to specimen collection when ordering the test.
QW | CLIA waived test (Not typically applicable) | Not applicable for 0604U which is a complex LC–MS/MS reference lab test; included for completeness only when a code denotes waived status.
XC | Modifier identifying a component service (separate encounter) | Use if payer requires segregation of a service component that is a distinct encounter (rare for PLA lab codes).
XE | Separate encounter | Use when the service was performed during a separate encounter on the same day (limited applicability to reference lab testing workflows).
XP | Separate practitioner | Use if a different practitioner performed a portion of the services and payer requires delineation (rare for centralized lab testing).
KX | Requirements specified in the medical policy are met | Use when documentation supports medical necessity per payer policy and the payer recognizes KX for diagnostic tests.
| Taxonomy Code | Specialty | Notes |
|---|---|---|
207K00000X | Allergy & Immunology | Specialists who commonly order bradykinin peptide testing for angioedema evaluation. |
207RR0500X | Clinical Pathology | Pathologists and laboratory medicine physicians involved in interpretation of specialized biochemical assays.
208000000X | Internal Medicine | Hospital-based or outpatient internists who may evaluate recurrent angioedema and order diagnostic labs.
2084P0800X | Pediatric Allergy & Immunology | Pediatric specialists ordering bradykinin testing in children with recurrent angioedema.
363L00000X | Clinical Laboratory Director | Laboratory directors overseeing reference lab testing performed by Virant Diagnostics Inc.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
T78.3 | Angioneurotic edema | Directly relevant as a code describing angioedema, a clinical indication for bradykinin peptide quantification. |
T78.2 | Anaphylactic shock, unspecified | Included when differentiating histamine-mediated angioedema from bradykinin-mediated forms; helps guide diagnostic workup.
D84.1 | Defects in the complement system | C1 inhibitor deficiency or other complement disorders may present with recurrent angioedema and are part of the differential diagnosis when ordering 0604U.
R60.0 | Localized edema | Used for localized swelling presentations evaluated with bradykinin testing if angioedema is suspected.
R60.9 | Edema, unspecified | General edema code that may accompany diagnostic evaluation including bradykinin peptide measurement.
Z13.6 | Encounter for screening for disorders of lipid metabolism (placeholder for screening encounters) | Not specific but sometimes used when ordering specialized lab screening panels; included for completeness.
Z01.818 | Encounter for other preprocedural examination | Used when bradykinin testing is part of preprocedural evaluation for patients with a history of angioedema to assess perioperative risk.
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
36415 | Collection of venous blood by venipuncture | Primary specimen collection method used to obtain whole blood for 0604U testing in outpatient settings. |
99000 | Handling and/or conveyance of specimen for transfer from patient to laboratory (usually bundled) | May be used by some facilities when separately billable specimen handling or courier services are charged in addition to laboratory testing.
82784 | Amino acids, quantitative, plasma or serum, amino acids (Note: not the same analyte) | Represents other quantitative mass spectrometry–based assays; listed as a related lab technology code but not a substitute for the proprietary PLA code 0604U.
0000U | Proprietary Laboratory Analyses example code (placeholder) | Illustrates that PLA tests use unique Category I PLA codes specific to a single manufacturer's test; 0604U is the PLA code for the Virant Diagnostics bradykinin assay.
99213 | Office or other outpatient visit for the evaluation and management of an established patient, moderate complexity | A typical E/M visit during which the clinician documents recurrent angioedema history and orders 0604U testing.