Coagulation Case Studies
Monday, August 18, 2008
AUGUST: ANSWERS TO CASE STUDIES
AUGUST: ANSWERS TO CASE STUDIES:
PT= 12.4 (11.5-13.8)
APTT= 45.7 (28.7-37.2)
APTT 1:1 Mix: 36.2 sec
Is this a correction? There are many different definitions to a correction for a mixing study. Some labs use a correction into the normal range, others use within 3 seconds of the PNP. This appears to be a partial correction. It is just 1 second into the normal range, but is 7 second from the PNP. Most labs would look at both an inhibitor and factor assays/
Factor Assays were performed?
How would this get reported out? The factor XI appears to be decreased, average 45% activity, however, a slight XI inhibitor appears to be present. This could account for the partial correction.
What is the optimum information to provide to the clinician? Since the factor IX is in the normal range, starts at 98% at a 1:10 and increased to 131% at 1:40, calling an inhibitor might be confusing to the clinician, and impact patient care. The factor XI should be reported.
A sample is sent on a 4 month old baby
Two small blue tops are received and the following tests are requested and performed. The results are as follows:
APTT = 68 seconds (25-35 sec)
Factor VIII = 35% at 1:10, 67% at 1:20 and 89% at 1:40
Factor IX = 56% 78% 102
Factor XI = 66 90 110
- Why is it important to know this sample is from a 4 month old baby? Several reasons: babies have different normal ranges, the tubes may be underdrawn, you would want to check for that 9:1 ratio. Another reason is that on a baby samples may be drawn through a line.
- Explain the results of the factor assay and possible causes? The results of all the assays begin in the abnormal range and as the sample is diluted, the value increases. This demonstrates the presence of an inhibitor. Possible causes are heparin or a direct thrombin inhibitor.
- In this situation, what testing should be performed? In this case no clot based assays should be performed.
- Can this sample be saved? If the sample is contaminated with heparin, the sample can be treated with hepzyme and the heparin will be neutralized, and the assays will reflect true levels.
Bleeding or Clotting that is the question?
An 18 year old male has right knee arthroscopy with a diagnosis of hemarthrosis. His own history is insignificant for bleeding, no epistaxis, gum bleeding, non bleeding at circumcision. The family history -- father had a prolonged APTT pre-operatively in his 40's, treated with DDAVP and diagnosed with von Willebrand's disease, grandfather is in his 80's with no history of bleeding, half-sister has a strong history of menorrhagia but is negative for von Willebrand disease.
Physical examination reveals joint laxity.
Coagulation testing results as follows:
PT= 13.7 sec (10.5-13.0)
1:1 mix = 11.2 sec
Control = 11.0 sec
APTT= 33.9 sec (24.5-34.5)
Fibrinogen= 282 mg/dL (180-400)
Fac VII = 33% (50-150%)
Fac 8 = 99% (50-150%)
vWF activity = 59% (50-150%)
vWF antigen = 78% (50-150%)
PFA/ADP = 68 sec (56-128 sec)
PFA/EPI = 139 sec ( 74-186 sec)
- Does this patient have von Willebrand Disease? Most vW workups include a PFA 100, APTT, Factor VIII assay, vW antigen and activity. All assays are normal. This doesn't appear to be von Willebrand disease.
- What is the most obvious diagnosis? Isolated prolonged PT, corrects into normal range and within 0.2 sec of the PNP suggests a factor deficiency. The factor VII is decreased.
- What might be alternative diagnosis? Possible Vitamin K deficiency - II, VII, IX and X
- What is the significance of joint laxity? This can be a characteristic in vascular bleeding disorders.
- What would be the final diagnosis and how would you treat this?Ehler-Danlos syndrome- autosomal dominant, rare connective tissue disorder. Bleeding is variable, it can range from petechiae, purpura, GI bleeds and might even be severe enough to suggest hemophilia.
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