Chromogenic Factor VIII assay
Clinical Background:
There are some mutations in the Factor VIII molecule which change its behaviour in the standard APTT based 1 stage Factor VIII assay. The mutations will typically lead to an overestimation of the F...
There are some mutations in the Factor VIII molecule which change its behaviour in the standard APTT based 1 stage Factor VIII assay. The mutations will typically lead to an overestimation of the Factor VIII activity in plasma by up to seven fold - the patient has a more severe bleeding diathesis than that suggested by the 1 stage Factor VIII result. The chromogenic assay is used to investigate and monitor these patients. There is also a mutation which gives a low result in the 1 stage assay but a considerably higher result in the chromogenic assay, again the bleeding symptoms are consistent with the chromogenic result. The assay is referred to as either a 2 stage assay or chromogenic assay as the procedure mimics the 2 stage assay with the generation of Xa
Test Details
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Discipline:
Haemostasis
Haemostasis
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Specimen Container Adult:
Light blue - sodium citrate
Light blue - sodium citrate
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Specimen Container Paediatric:
Light blue - sodium citrate
Light blue - sodium citrate
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Minimum Volume Adult:
2.7ml
2.7ml
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Minimum Volume Paediatric:
1.3ml
1.3ml
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Special Requirement:
Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.
Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.
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Sample Stability:
4 hrs
4 hrs
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Transport Requirements:
Sample must be transported to lab without delay (see sample stability information)
Sample must be transported to lab without delay (see sample stability information)
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Freq Analysis:
As required or weekly
As required or weekly
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Add On Test:
tnu-tr.bloodsciencesadditions@nhs.net (external)
tnu-tr.bloodsciencesadditions@nhs.net (external)
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Quality Assurance:
UK NEQAS Blood Coagulation
UK NEQAS Blood Coagulation
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Reference Ranges:
50 - 150IU/dL
50 - 150IU/dL
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Routine Contact Name:
RVI or Freeman Section Leaders
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Routine Telephone:
RVI: 0191 2820332, Freeman: 0191 2231195
RVI: 0191 2820332, Freeman: 0191 2231195
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Specialist Test:
yes
yes
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Specialist Contact Name:
Haematology and Haemostasis Healthcare Scientist
Haematology and Haemostasis Healthcare Scientist
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Specialist Telephone:
0191 2139758
0191 2139758
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Specialist Email:
alison.brown93@nhs.net
alison.brown93@nhs.net