Platelet Autoantibody Test (ITP Workup)

Also Known as (Alias) Platelet Flow Cytometry
Method Flow Cytometry
Test Information Idiopathic Thrombocytopenic Purpura (ITP) is a diagnosis associated with elevated platelet associated IgG, IgM or both. Positive autoantibody test results are indicative of autoimmune destruction. Positive indirect antibody test results, using patient’s plasma against normal random platelets, may indicate ITP depending upon the patient’s transfusion or pregnancy history. In approximately 85% of patients with ITP, the presence of an autoantibody can be detected.
Additional Test Information Patients who require autoantibody testing must be platelet transfusion independent for approximately 5 days to ensure that the platelets being tested are the patient’s own platelets and not circulating donor platelets.
Sample Requirements Citrate (blue top)
EDTA (lavender top)
Requested Volume 5cc Citrate (blue top)

EDTA (lavender top) for amount refer below

Platelet Count
Greater or equal to 50,000    Draw 20cc EDTA
20,000 to 49,999                     Draw 30cc EDTA
10,000 to 20,000                     Draw 40cc EDTA
Less than 10,000                     DO NOT DRAW***

***We cannot recover sufficient platelets to perform a direct assay of antibody bound to  autologous platelets. Contact Lab Supervisor for testing options at 206-689-6542.

Sample Information Samples must be received Monday thru Friday morning.  Samples received after 10:00am on Friday or over the weekend will have to be re-drawn.
Shipping Information Send whole blood specimens at ambient temperature. Specimens should arrive in the lab within 24 hours from draw time.

Send samples to:
Bloodworks Northwest
Attn: Platelet Immunology Lab, Rm 619
921 Terry Avenue
Seattle, WA 98104

For additional information, please see Ordering Information

Requisition Form RFT- Platelet Immunology Laboratory
Transaction Code 3640-00
CPT Codes 86022 x2, 86023 x2
Test Schedule Monday thru Friday morning
Turn around Time (analytic time) 1 business day
Report/Results Fax number required to receive report

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