The following results were obtained from a 55-year-old female following an uneventful cholecystectomy:
Parameter |
Patient Value |
Adult Normal Range |
Prothrombin time (PT) |
16.0 sec |
12.0 – 16.5 |
International normalised ratio (INR) |
1.2 |
0.9 – 1.3 |
Activated partial thromboplastin time (APTT) |
56.0 sec* |
27.0 – 38.5 |
Fibrinogen |
2.8 g/L |
2.0 – 4.0 |
Platelet count |
223 x 109/L |
150 – 350 |
APTT mixing study |
52 sec |
a) List three causes of these results. What further blood tests would help to differentiate between them? (20% marks)
Other tests:
The history (cholecystectomy, etc) does not seem to serve much of a purpose here, as it dis not appear to have factored into the college's answer. In summary, this is an isolated raised APTT which does NOT reverse with a mixing study. The patient's blood, as it is mixed with a normal sample, makes the normal sample coagulopathic. There must be some sort of anticoagulant factor in it. Which one?
The three major candidates are:
The following tests are reasonable:
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