Which lab studies are indicated in the workup of platelet-associated immunoglobulin G?

Updated: Nov 30, 2019
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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The autoantibodies responsible for autoimmune thrombocytopenia do not induce complement-mediated lysis. Furthermore, when platelets are destroyed in the circulation, they internalize plasma proteins, including immunoglobulin. Platelets also have low affinity to the crystallizable fragment (Fc) receptor, FcgRIIa, that binds immunoglobulin.

In patients with autoimmune thrombocytopenia, the larger platelets have proportionately more membrane surface and more Fc receptor than normal platelets. For these reasons, the detection of increased platelet-associated immunoglobulin is not useful because it is elevated in almost all conditions associated with thrombocytopenia, which limits the value of this test in the diagnosis of ITP. Specialized tests to identify antibodies that react specifically against platelet membrane glycoproteins are not clinically available.

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