Bone marrow examination may be performed on patients over the age of 60 and those who do not respond to treatment, or when the diagnosis is in doubt.  On examination of the marrow, an increase in the production of megakaryocytes may be observed and may help in establishing a diagnosis of ITP.  An analysis for anti-platelet antibodies is a matter of clinician's preference, as there is disagreement on whether the 80 percent specificity of this test is sufficient to be clinically useful.