Imperial Collage Healthcare

Thrombophilia screen


Test Background
The thrombophilia screen includes the following:
• coagulation screen
• lupus anticoagulant
• protein C
• protein S
• antithrombin assays
• Factor V Leiden
• Prothrombin gene mutation testing


Clinical Indications

  • The predictive value of inherited thrombophilia screening in those who have a history of venous thromboembolism has been over-estimated in the past, and for family members of affected individuals. Likewise, the association between positive inherited thrombophilia tests and adverse pregnancy outcomes is somewhat controversial. Furthermore, inherited thrombophilia tests are a form of genetic testing. Discussion on an individual patient basis with Haematology may be appropriate in many cases.
  • Please note: cardiolipin antibodies and β2-glycoprotein antibodies should be requested in conjunction with the lupus anticoagulant test to cover the spectrum of antibodies for possible acquired antiphospholipid syndrome.
  • Venous thromboembolism at a young age (including childhood)
  • Recurrent venous thromboembolism
  • Unusual site of thrombosis (eg. mesenteric, renal, portal veins, cerebral venous sinuses)
  • Thrombosis during pregnancy or puerperium
  • Recurrent superficial thrombophlebitis
  • Arterial thrombosis at a young age (<40 years)
  • A family history of any of the above
  • A first degree relative with diagnosed thrombophilia
  • Recurrent pregnancy loss (3 or more in the second trimester)
  • Severe or recurrent intrauterine growth retardation
  • Severe or recurrent pre-eclampsia
  • Other recurrent obstetric complications (abruptio placentae, pre-term delivery)
  • Neonatal purpura fulminars or massive thrombosis in newborn
  • Warfarin-induced skin necrosis


Reference Range

PT 9-12 s
APPT 23-31 s
Fibrinogen 1.8-4.0 g/L
TT 13-19 s
Protein C 70-140 IU/dL
Protein S free (F) 50-110 IU/dL
Protein S free (M) 70-120 IU/dL
Antithrombin activity 80-120 IU/dL


Sample Required
4 x 4.5 mL sodium citrate (pale blue top) adults
4 x 1.8 mL sodium citrate (pale blue top) paediatrics
Plus 1 x 4 mL EDTA (lavender top) adults
or 1 x 0.5 mL EDTA (lavender top) paediatrics


Turnaround Time
10-14 days


Notes
Special handling: avoid prolonged stasis during venepuncture.
Sample must be received by lab within 2 hours of collection.
Please note: sodium citrate samples will be rejected if underfilled, clotted, haemolysed or if patients are receiving anticoagulant therapy. Similarly, sampling is inappropriate within 4 weeks post-childbirth or during an acute phase inflammatory response.
See cardiolipin antibodies and β2-glycoprotein antibodies, Immunology, Factor V Leiden and prothrombin gene mutation, Molecular Diagnostics.

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