Factor IX Inhibitor Profile, Comprehensive

Also known as: Bethesda Titer

Clinical Use

Order Test

Use

Confirmation and characterization of factor IX inhibitor

Special Instructions

Not provided.

Limitations

Residual coagulation factor activity can falsely lower the Bethesda titer result. Lupus anticoagulant activity and the presence of antithrombotic agents that function as inhibitors should be ruled out prior to testing to avoid false positives. Furthermore, some inhibitors may fully neutralize factors in less than two hours and autoimmune inhibitors with second order kinetics cannot be accurately measured by the Bethesda titer system.

Test Details

Methodology

Immunoassay (Other)

Biomarkers

Activated Partial Thromboplastin Time (aPTT)

Analyte

Activated Partial Thromboplastin Time

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Factor IX Activity

Analyte

Factor IX Activity

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Factor IX Bethesda Titer

Analyte

Factor IX Bethesda Titer

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

96459-3 - Fact IX Act + Inhib Pnl PPP

Result Codes

14979-9 - aPTT PPP
5946-9 - aPTT imm NP Cont PPP
43734-3 - aPTT saline 1:1 PPP
30323-0 - aPTT 1h NP Cont PPP
44950-4 - aPTT 1h NP Cont PPP Cont
3187-2 - Fact IX Act/Nor PPP
3185-6 - Fact IX Inhib PPP-aCnc

Result Turnaround Time

2-5 days

Specimen

Plasma

Volume

6 mL (2 mL in each of three tubes)

Minimum Volume

Not provided

Container

Blue-top (sodium citrate) tubes

Collection Instructions

Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested.