USMLE Forum Archives - USMLE Step 2 CK - hematology
hematology
sudha2015 - 01-12-11 12:46
An 18-month-old boy is taken to his family doctor for evaluation of easy bruising and decrease range of motion of the right knee. On examination, he had multiple large ecchymoses, mostly in the lower extremities, and a right knee hemarthrosis. He has not had surgery or family history of a bleeding disorder. Initial blood tests reveal a prolonged activated partial thromboplastin time (aPTT) with a normal PT and platelet count. What further tests should be ordered to make a diagnosis in this boy?
A. factor VII
B. factors II, VII, IX, and X
C. bleeding time
D. factors XI, IX, VIII
E. factor I and II
sudha2015 - 01-12-11 12:46
An 18-month-old boy is taken to his family doctor for evaluation of easy bruising and decrease range of motion of the right knee. On examination, he had multiple large ecchymoses, mostly in the lower extremities, and a right knee hemarthrosis. He has not had surgery or family history of a bleeding disorder. Initial blood tests reveal a prolonged activated partial thromboplastin time (aPTT) with a normal PT and platelet count. What further tests should be ordered to make a diagnosis in this boy?
A. factor VII
B. factors II, VII, IX, and X
C. bleeding time
D. factors XI, IX, VIII
E. factor I and II
Page 1
#1
Re: hematology babbu5508 - 01-12-11 13:13 D. factors XI, IX, VIII...the findings are likely suggestive of hemophilia which can be confirmed by an assay of coagulation factors..
#2
Re: hematology
sudha2015 - 01-12-11 13:45 D
The PTT represents the time for clot formation after adding calcium, phospholipids, and kaolin to citrated blood. It is prolonged by heparin, direct thrombin inhibitors, a deficiency or inhibitor for factors in the intrinsic and common pathway (i.e., factors II, V, VIII, IX, X, XI, XII) as well as lupus anticoagulant, vitamin K deficiency, or severe liver disease.
The PT represents the time for clot formation after the addition of thromboplastin (tissue factor) and calcium to citrated blood. It is prolonged with deficiencies of the extrinsic and common pathway factors II, V, VII, X, or fibrinogen; liver disease; vitamin K deficiency and Warfarin use.
Page 1