Summary & Overview
CPT 85210: Prothrombin (Factor II) Clotting Test
CPT code 85210 denotes a laboratory clotting assay to detect factor II (prothrombin) in patient serum. This test is clinically significant for evaluating coagulation pathway function and for diagnosing or monitoring disorders that affect prothrombin levels or activity. Nationally, such assays are part of routine hematology and coagulation testing panels used in hospitals, reference laboratories, and specialty clinics, with implications for anticoagulation management and bleeding disorder workups.
Key payers evaluated in this summary include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The analysis addresses coverage and billing contexts across major commercial and federal payers to provide a national perspective on clinical use and administrative handling.
Readers will find a concise overview of clinical context, the typical settings where the test is performed, payer coverage patterns, and guidance on what information is available versus missing. The publication identifies benchmarks and policy-relevant considerations, highlights common billing modifiers associated with laboratory services, and notes areas where input data are not provided. Data not available in the input are explicitly indicated.
Billing Code Overview
CPT code 85210 describes a laboratory clotting test performed by a lab analyst to determine the presence of factor II (prothrombin) in a patient’s serum. The procedure assesses the presence or activity of prothrombin, a key clotting protein involved in the coagulation cascade.
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Service type: Laboratory diagnostic test
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Typical site of service: Clinical laboratory or hospital laboratory setting
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A 54-year-old man on warfarin therapy presents for evaluation after an elevated international normalized ratio (INR) and a recent minor bleeding episode from the gums. The treating hematologist orders specific coagulation factor testing, including a prothrombin (factor II) clotting assay, to assess vitamin K–dependent factor levels and investigate possible acquired or congenital deficiencies. A phlebotomy technologist draws blood in a citrate tube and sends the specimen to the hospital central laboratory. A medical laboratory scientist performs the clot-based assay to measure factor II activity, documents results in the electronic laboratory system, and communicates critical low values to the ordering hematologist.
Typical workflow steps:
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Order placed by hematology or anticoagulation clinic with indication (e.g., abnormal INR, unexplained bleeding).
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Specimen collection by outpatient phlebotomy or inpatient nursing; sent to the hospital clinical lab.
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Lab accessioning and plasma preparation (centrifugation to obtain platelet-poor plasma).
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Clotting assay performed by a laboratory analyst using factor-deficient substrate or chromogenic methodology as appropriate.
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Result verification by supervising clinical pathologist or lab director and reporting to the ordering clinician.
Typical site of service: hospital or independent clinical laboratory with coagulation testing capability.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation or oversight component of the lab test if separate from the technical component. |
| TC | Technical component | Use when billing only the technical component (laboratory performance and materials) of the test.
| 90 | Reference (outside) lab | Use when the performing laboratory sends the specimen to another laboratory for testing and the other lab performed the test.
| 52 | Reduced services | Use when the test is partially performed or limited in scope compared with standard procedure.
| 53 | Discontinued procedure | Use if specimen processing or testing was started but discontinued for documented clinical reasons.
| 59* | (Not in provided list) | Data not available in the input. |
| 22 | Increased procedural services | Use when work or resources required to perform the test are substantially greater than usual (e.g., troubleshooting unusual specimen or complex validation).
| 78 | Return to OR for related procedure | Not typically applicable to lab testing; use only if related surgical reoperation affected specimen handling and billing requires this modifier.
| 80 | Assistant surgeon | Not applicable to lab service; included in list but not routinely used for this code.
| 95 | Synchronous telemedicine service rendered via real-time interactive audio and video | Use when result interpretation includes real-time teleconference with the ordering clinician and payer allows modifier for professional service.
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 207RH0000X | Hematology | Physicians who order and interpret coagulation factor testing. |
| 207K00000X | Hematology & Oncology | Specialists managing bleeding and clotting disorders.
| 362X00000X | Clinical Laboratory | Medical laboratory scientists and pathologists performing and supervising testing.
| 2080P0106X | Pathology | Pathologists overseeing coagulation laboratories.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
D68.3 | Hemorrhagic disorder due to intrinsic circulating anticoagulants | Can present with low factor II activity due to inhibitors; testing for factor II helps identify etiology. |
| D69.5 | Secondary thrombocytopenia | Part of differential diagnosis for bleeding; coagulation factor testing distinguishes platelet vs coagulation defects.
| D68.9 | Coagulation defect, unspecified | Factor II assay is used to define specific clotting factor deficiencies within this category.
| Z79.01 | Long term (current) use of anticoagulants | Patients on warfarin may have abnormal coagulation tests; factor II assay may be indicated when unexpected bleeding or lab anomalies occur.
| D68.4 | Acquired coagulation factor deficiency | Directly relevant—factor II levels are measured to confirm acquired deficiencies.
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
85306 | Prothrombin time (PT) test | Common screening test for extrinsic coagulation pathway; often ordered prior to specific factor II assay to evaluate overall clotting status. |
| 85610 | Prothrombin time, partial thromboplastin time, and INR—commonly reported as PT/INR and PTT | Used in anticoagulation monitoring; abnormal results prompt specific factor assays such as factor II.
| 85220 | Clotting test for factor V | Other individual clotting factor assays frequently ordered in the evaluation of bleeding disorders alongside factor II testing.
| 85315 | Platelet function analysis | Performed when platelet-related bleeding is suspected in addition to coagulation factor deficiencies.
| 86140 | Fibrinogen assay | Assesses fibrinogen level; part of broader coagulation evaluation that may accompany factor II testing.