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Prothrombin Genotyping for Thrombotic Risk Assessment

Prothrombin Mutation Analysis, Factor II genotyping, Prothrombin 20210 mutation analysis

Test Codes

EPIC: LAB6389, Beaker: GPROG

Department

Molecular Pathology

Instructions

This test is available to outpatients only and should only be ordered once in a lifetime. For questions, please call 800-551-0488.

Specimen Collection Criteria

Collect: One 10.0 mL whole blood in Lavender-top EDTA tube. (Minimum: 5.0 mL)

Physician Office/Draw Specimen Preparation

Do not freeze specimens. Maintain whole blood refrigerated (preferred) (2-8°C or 36-46°F) or at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: Whole blood at room temperature (20-26°C or 68-78.8°F) or refrigerated (preferred) (2-8°C or 36-46°F). (Minimum: 5.0 mL whole blood)

Rejection Criteria

• Frozen specimens. 
• Centrifuged specimens.
• Mislabeled or unlabeled tubes. 
• Specimens collected in heparin tubes (Green-top), clot tubes (Red-top), or SST tubes.
• Specimens not collected and processed as indicated.
• This test will only be performed once in a lifetime for a patient.

Clients will be notified of any cancellations of testing.

In-Lab Processing

Do not freeze specimens. Maintain specimen refrigerated (2-8°C or 36-46°F) prior to testing.

Storage

Specimen Stability for Testing:

Whole Blood
Room Temperature (20-26°C or 68-78.8°F): 72 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Molecular Pathology Laboratory

Performed

At least once per week.
Results available in 7-10 business days.

Reference Range

Negative (no mutation).

Test Methodology

Integrated sample purification, nucleic acid amplification, and detection of the target sequences using real-time polymerase chain reaction (PCR).

Interpretation

The prothrombin 20210 mutation is a G to A substitution in the 3'-UT region of the prothrombin gene. It has been found in 18% of patients with documented family history of venous thrombosis, 6% of unselected patients with a first episode of deep vein thrombosis and in 1% - 2% of healthy control subjects.

Clinical Utility

• The prothrombin genotyping is a molecular test for detection of the prothrombin gene mutation G20210A, which results in elevated prothrombin levels and increased risk of venous thrombosis (2.8-fold compared to genotypically normal individuals). Increased risk for arterial thrombosis has also been reported.
• Testing for Prothrombin Mutation is recommended for:
  • Patients with history of recurrent venous thromboembolisms (VTE), patients with VTE at younger age (less than 50 years), unprovoked VTE at any age, VTE at unusual sites (cerebral, mesenteric, portal, hepatic, vena cava).
  • Patients with positive family history of VTE.
  • Women with VTE during pregnancy/post-partum, oral contraceptive, or hormone replacement therapy.
  • Women with unexplained pregnancy loss.
  • Prior to oral contraceptive use or pregnancy in asymptomatic females, first degree relatives of family member with identified mutation.
  • Children with venous or arterial thrombosis and children who are siblings of patients with early symptomatic VTE.
  • Patients with unexplained arterial thrombosis without atherosclerosis or young patients who smoke.

CPT Codes

81240

Contacts

Last Updated

11/2/2023