Platelet Antibody Test
Synonyms
Serotonin Release,
Specimen
Plasma
Container
Two blue top (sodium citrate) tubes
Collection
Routine venipuncture. If multiple tests are ordered, coagulation tests should be drawn last.
Storage Instructions
Separate plasma from red blood cells, place it in a plastic tube (12 x 75 mm), and freeze at -25°C.
If testing for platelet-associated IgG and the sample is to be sent to a reference lab, draw into acid citrate dextrose and store at 4°C to preserve platelet yield.
Preserved platelet-based testing is emerging as a more streamlined approach.
Reason to Reject Sample
- Hemolyzed specimen
- Unfrozen stored plasma
- Clotted specimen
Special Instructions
Contact the laboratory before ordering. Platelet antibody testing is not routinely available in all labs.
Reference Range
Within control range (determined with each test run)
Use
Used to detect and monitor immune thrombocytopenia and the presence of antiplatelet antibodies causing platelet destruction.
Limitations
The serotonin release assay may not detect all platelet antibodies in patients with idiopathic thrombocytopenic purpura (ITP).
Methodology
Serotonin Release Assay: Patient plasma is incubated with 14C-serotonin labeled platelets from healthy donors.
The release of serotonin indicates antibody-mediated activation.
Additional Information
Detection of platelet antibodies is complex and clinically significant.
Even healthy individuals may have ~4,000 IgG molecules per platelet without thrombocytopenia.
These IgGs can be true antiplatelet antibodies or nonspecifically bound immunoglobulins or immune complexes.
There are over 20 commercial tests for platelet antibody detection due to ongoing challenges in achieving standardization and specificity.
Autoantibodies in ITP often target glycoprotein IIb/IIIa or unknown platelet proteins.
In ITP diagnosis and post-transfusion monitoring:
Combining platelet crossmatching with ELISA for IgA and radiolabeled staphylococcal protein A assays helps evaluate platelet survival and transfusion efficacy.
References
- Jacobs et al., Laboratory Test Handbook, Lexi-Comp Inc, 1994
- George JN, Prog Hemost Thromb, 1991; 10:97–126
- Karpatkin S, Semin Hematol, 1985; 22:260–88
- McMillan R, Clin Lab Haematol, 1983; 12:69–88
- Schwartz KA, Am J Hematol, 1988; 29:106–14
