Factor assays (one-stage clotting): FII, FV, FVII, FVIII, FIX, FX, FXI, FXII, PK, HMWK
- Description
- One-stage clotting assays for determining coagulation factor function are based on the ability of dilutions of patient's plasma to correct the clotting time of a plasma that has normal levels of all clotting factors except the one being measured, in which it is totally deficient. Clotting times are derived via prothrombin time reagents for factors II, V, VII & X, and APTT-derived for factors VIII, IX, XI, XII, prekallikrein and HMWK. Results are assessed from a parallel line bioassay graphical plot against that of a standard plasma.
- Clinical details
- The complex orchestration of cellular and molecular participants of haemostasis achieves a crucial yet fine balance of procoagulant and anticoagulant mechanisms. Quantitative or qualitative deficiency of a procoagulant integral to the molecular interplay converging on fibrin formation reduces ability to form clots and can give rise to a bleeding disorder. Deficiencies of FXII, prekallikrein & high molecular weight kininogen from the so-called contact pathway are not associated with bleeding disorders but can elevate an APTT, so the assays are available as part of the repertoire to investigate elevated APTTs when necessary.
- Related condition
- Reference range
- FII 50 - 150 FV 50 - 150 FVII 50 - 150 FVIII 50 - 150 FIX 50 - 150 FX 50 - 150 FXI 57.9 - 118.5 FXII 50 - 150 PK 50 - 150 HWMK 50 - 150
- Units
- IU/dl
- Testing site
- Synnovis : Blood Sciences : St Thomas' Hospital
- Laboratory
- Diagnostic Haemostasis and Thrombosis
- Sample type and volume required
- External requests: Citrated platelet poor plasma 500µL x 1 aliquot for 2 factor assays Internal requests: please refer to EPR label
- Special sample instructions
The samples should be analysed or manipulated & stored in the laboratory within 4 hours of venepuncture. Please ensure sample tubes are filled exactly to the fill-line as underfilling creates a dilution error and leads to inaccurate results.
- Turnaround time
- 7 - 10 days
- Contacts
Diagnostic Haemostasis and Thrombosis Department
St Thomas’ Hospital
Phone: 020 7188 2797
St Thomas’ Hospital
North Wing – 4th and 5th Floors
Westminster Bridge Road
London SE1 7EHGuy’s Hospital
Phone: 020 7188 7188 ext. 53860
Guy’s Hospital
Southwark Wing – 4th Floor
Great Maze Pond
London SE1 9RT
Outside core hours, contact Duty Haemostasis Biomedical Scientist