Thrombasthenia Workup

Updated: Oct 25, 2018
  • Author: Vivian Y Chang, MD, MS; Chief Editor: Robert J Arceci, MD, PhD  more...
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Workup

Laboratory Studies

A history of prolonged bleeding, a prolonged bleeding time, and failure of platelets to aggregate in response to L-epinephrine, adenosine 5'-diphosphate (ADP), collagen, and arachidonic acid are diagnostic of thrombasthenia. Note that response to ristocetin in platelet aggregation studies is normal.

The platelet function assay PFA-100 (Dade-Behring; Miami, Fla) can replace bleeding times and may aid in the diagnosis of Glanzmann thrombasthenia (GT). The PFA-100 measures the time to closure when blood is passed through a collagen filter. This time is prolonged in patients with GT. [14]

A CBC count and peripheral smear may also be helpful to suggest the degree of bleeding and rule out other potential causes. Patients who are thrombasthenic have platelet counts within the reference range and, on blood smear findings, normal platelet morphology.

Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are within reference ranges.

A urinalysis may reveal proteinuria and microscopic hematuria.

The diagnosis of GT should always be confirmed by documenting the deficiency of GP IIb-IIIa using flow cytometry or immunoblot analysis.

Various methods have been used for genetic testing and screening for mutations in GPIIb and GPIIIa, including single strand conformation analysis (SSCP), conformation sensitive gel electrophoresis (CSGE), and denaturing gradient gel electrophoresis (DGGE).

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Imaging Studies

Perform head CT scanning in patients with a history of the disease and head trauma. Abdominal CT should be performed after abdominal trauma.

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