hemat 1 - darkhorse

[ArchivalUser]

All the following cause prolongation of the activated partial thromboplastin time (aPTT) that
does not correct with a 1:1 mixture with pooled plasma EXCEPT


A. lupus anticoagulant
B. factor VIII inhibitor
C. heparin
D. factor VII inhibitor
E. factor IX inhibitor

[ArchivalUser]

D.
donno if I'm understanding somewhat not so straight phrasing of this q

[ArchivalUser]

C?

[ArchivalUser]

C

[ArchivalUser]

if i pick A.

[ArchivalUser]

Aa

[ArchivalUser]

AA

[ArchivalUser]

The answer is D.


The aPTT involves the factors of the intrinsic pathway of coagulation. Prolongation of the aPTT
reflects either a deficiency of one of these factors (factor VIII, IX, XI, XII, etc.) or inhibition of
the activity of one of the factors or components of the aPTT assay (i.e., phospholipids). This
may be further characterized by the "mixing study," in which the patient's plasma is mixed with
pooled plasma. Correction of the aPTT reflects a deficiency of factors that are replaced by the
pooled sample. Failure to correct the aPTT reflects the presence of a factor inhibitor or
phospholipid inhibitor. Common causes of a failure to correct include the presence of heparin in
the sample, factor inhibitors (factor VIII inhibitor being the most common), and the presence of
antiphospholipid antibodies. Factor VII is involved in the extrinsic pathway of coagulation.
Inhibitors to factor VII would result in prolongation of the prothrombin time