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  #1  
Old 09-24-2012
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Blood Platelets with Primary Wave Defect

A 5-year-old boy is being evaluated for recurrent epistaxis and other abnormal bleeding episodes, including excessive bleeding from the umbilical cord at birth. Laboratory studies reveal the following: decreased hemoglobin (with microcytic hypochromic red cell indices), normal platelet count, markedly prolonged prothrombin time (PT) and partial thromboplastin time (PTT), and unmeasurable thrombin time (TT). Platelet aggregation studies reveal a normal platelet response to ristocetin, but with other substances (including collagen, ADP, and epinephrine), this patientís platelets exhibit a primary wave defect. Based on these findings, this patient most likely has:

a. Afibrinogenemia
b. Bernard-Soulier syndrome
c. Glanzmannís thrombasthenia
d. Gray platelet syndrome
e. Wiskott-Aldrich syndrome
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Old 09-24-2012
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Old 09-24-2012
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Quote:
Originally Posted by Fuser00 View Post
A 5-year-old boy is being evaluated for recurrent epistaxis and other abnormal bleeding episodes, including excessive bleeding from the umbilical cord at birth. Laboratory studies reveal the following: decreased hemoglobin (with microcytic hypochromic red cell indices), normal platelet count, markedly prolonged prothrombin time (PT) and partial thromboplastin time (PTT), and unmeasurable thrombin time (TT). Platelet aggregation studies reveal a normal platelet response to ristocetin, but with other substances (including collagen, ADP, and epinephrine), this patientís platelets exhibit a primary wave defect. Based on these findings, this patient most likely has:

a. Afibrinogenemia
b. Bernard-Soulier syndrome
c. Glanzmannís thrombasthenia
d. Gray platelet syndrome
e. Wiskott-Aldrich syndrome
Afibrinogenemia
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Old 09-24-2012
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my pure guess a) afibrinogenemia

i think no options are matched...

wiscott aldrich----thrombocytopenia(decreased platelet count)

bernard soulier----abnormal ristocetin assay

glanzmann thromasthenia-------PT,APTT normal mostly

gray platelet-----don't know abt this one
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Old 09-24-2012
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Default a. Afibrinogenemia

A 5-year-old boy is being evaluated for recurrent epistaxis and other abnormal bleeding episodes, including excessive bleeding from the umbilical cord at birth. Laboratory studies reveal the following: decreased hemoglobin (with microcytic hypochromic red cell indices), normal platelet count, markedly prolonged prothrombin time (PT) and partial thromboplastin time (PTT), and unmeasurable thrombin time (TT). Platelet aggregation studies reveal a normal platelet response to ristocetin, but with other substances (including collagen, ADP, and epinephrine), this patientís platelets exhibit a primary wave defect. Based on these findings, this patient most likely has:

a. Afibrinogenemia- i think its congenital fibrin defect. So prolonged PT, pTT and unmeasureable TT

b. Bernard-Soulier syndrome - normal PT, PTT and ristocetin test negative

c. Glanzmannís thrombasthenia- normal PT, PTT

d. Gray platelet syndrome- Alpha granules absence in blood platelet. Alpha granules contain vWF and fibrinogens and may be heparin neutralizing factor (not sure)- Still not sure this may be answer.

e. Wiskott-Aldrich syndrome- thrombocytopenia
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Old 09-25-2012
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Default my answer :)

a. Afibrinogenemia
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Old 09-25-2012
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Quote:
Originally Posted by Fuser00 View Post
A 5-year-old boy is being evaluated for recurrent epistaxis and other abnormal bleeding episodes, including excessive bleeding from the umbilical cord at birth. Laboratory studies reveal the following: decreased hemoglobin (with microcytic hypochromic red cell indices), normal platelet count, markedly prolonged prothrombin time (PT) and partial thromboplastin time (PTT), and unmeasurable thrombin time (TT). Platelet aggregation studies reveal a normal platelet response to ristocetin, but with other substances (including collagen, ADP, and epinephrine), this patientís platelets exhibit a primary wave defect. Based on these findings, this patient most likely has:

a. Afibrinogenemia
b. Bernard-Soulier syndrome
c. Glanzmannís thrombasthenia
d. Gray platelet syndrome
e. Wiskott-Aldrich syndrome
b and c has normal PT/APTT. E has MRTEXT: decreased igM, Recurrent infection,T and B cell defect, Eczema,X linked,Thrombocytopenia,. Dont know about d. best guess ==a.
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Old 09-25-2012
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Wow, nice question!
Will go with A..
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  #9  
Old 09-25-2012
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Default Answer A

Platelet aggregation refers to platelets binding to other platelets. One mechanism for this involves fibrinogen, which can act as a molecular bridge between adjacent platelets by binding to GpIIb and GpIIIa receptors on the surface of platelets. Abnormalities of platelet aggregation (aggregation defects or primary wave defects) include Glanzmannís thrombasthenia and afibrinogenemia.

Patients with Glanzmannís thrombasthenia have a deficiency of GpIIb-IIIa and defective platelet aggregation. Patients with low or no fibrinogen levels characteristically have prolonged PT, PTT, and TT values: in fact, they are so prolonged they are unmeasurable.
In contrast to platelet aggregation, platelet secretion refers to the secretion of the contents of two types of granules within the platelet cytoplasm.

Alpha granules contain fibrinogen, fibronectin, and platelet-derived growth factor, while dense bodies contain ADP, ionized calcium, histamine, epinephrine, and serotonin. Decreased platelet secretion (activation defects) is seen with deficiencies of these granules; these diseases are called storage pool defects. They can involve either alpha granules (gray platelet syndrome) or dense bodies (Chťdiak-Higashi syndrome, Wiskott-Aldrich syndrome, or TAR).

Wiskott-Aldrich syndrome is an X-linked disorder that is characterized by eczema, thrombocytopenia (small platelets), and immunodeficiency consisting of decreased levels of IgM and progressive loss of T cell function. These patients have recurrent infections with bacteria, viruses, and fungi. Thrombocytopenia-absent radius (TAR) syndrome refers to the combination of thrombocytopenia and absent radii
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