darkhorse
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You are asked to consult on a 31-year-old male with prolonged bleeding after an oral surgery
procedure. He has no prior history of bleeding diathesis or family history of bleeding disorders.
The patient's past medical history is remarkable for infection with the human immunodeficiency
virus, with a CD4 count of 51/mL3. The examination is remarkable only for spotty
lymphadenopathy. The platelet count is 230,000 cells/mL. His international normalized ratio
(INR) is 1.5. Activated partial thromboplastin time is 40 s. Peripheral blood smear shows no
schistocytes and is otherwise unremarkable. A 1:1 mixing study corrects both conditions
immediately and after a 2-h incubation. Fibrinogen level is normal. Thrombin time is prolonged.
What is the diagnosis?
A. Disseminated intravascular coagulation (DIC)
B. Dysfibrinogenemia
C. Factor V deficiency
D. Liver disease
E. Factor XIII deficiency
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| drdg
Forum Senior
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I will go for C. Factor V deficiency
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| cool doctor
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I think itsE
but Im not sure if they have prolonged thrombin time
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| titly
Forum Elite
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i think it should be B. Dysfibrinogenemia.
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| dudefop
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It's B. dysfibrinogenemia.
If Thrombin time is prolonged, you should think about fibrinogen( eg. DIC, Liver diseases) or heparin therapy.
Since aPTT is normal heparin therapy can be excluded.
The remaining is fibrinogen, but here the level of fibrinogen is normal.
So it should be some kind of malfunction of fibrinogen instead of fibrinogen deficiency or others.
Edited by dudefop on 11/11/07 - 12:42 AM
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| darkhorse
Forum Elite
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B
Fibrinogen is a 340-kDa dimeric molecule made up of two sets of three covalently linked
polypeptide chains. Thrombin cleaves multiple peptides to produce fibrin monomer that factor
XIII stabilizes by cross-linking. Although fibrinogen is needed for platelet aggregation and fibrin
formation, even severe fibrinogen deficiency such as afibrinogenemia produces mild, rare
bleeding episodes, most often after surgery. Dysfibrinogenemia refers to a constellation of
disorders that involve mutations that alter the release of fibrinopeptides, affect the rate of
polymerization of fibrin monomers, or alter the sites of fibrin cross-linking. Dysfibrinogenemia
is either inherited in an autosomal dominant fashion or acquired. Patients with liver disease,
hepatomas, AIDS, and lymphoproliferative disorders may develop an acquired form of
dysfibrinogenemia. The presence of altered partial thromboplastin time (PTT) and prothrombin
time (PT)/INR reflects an abnormality in coagulation from the prothrombinase complex
downstream to fibrin. Correction with a mixing study eliminates factor inhibition as a cause of
the coagulation disorder. Other causes of prolongation of the PT and PTT include factor
deficiencies in factor V or X, afibrinogenemia or dysfibrinogenemia, and consumption of
coagulation factors from DIC. The absence of schistocytes from the blood smear makes DIC
unlikely. The thrombin time tests the interaction with thrombin directly on fibrinogen. Its
prolongation indicates an abnormality with that interaction and suggests a diagnosis of
dysfibrinogenemia. Factor XIII deficiency is a bleeding disorder that manifests in childhood and
is not consistent with this presentation.
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