Answer to CBC Case Study on TTP

Patient 1 has ITP, patient 2 has Evans syndrome.

What are some of the clues from the CBCs?

• The severe degree of thrombocytopenia in patient 1 is more typical of TTP.
• The daily blood tests in patient 1 are consistent with being an inpatient, while the cadence of testing in patient 2 is not.
• The initial microcytosis in patient 1 is consistent with TTP (a low MCV is part of the PLASMIC score). This occurs because red blood cell fragments (schistocytes) are, by definition, smaller than intact mature red blood cells.

Note: patient 1 does not mount a very brisk retic response, presumably because of an inflammatory block.

Patient 1

Patient 2