These laboratory findings are associated with TTP and HUS:
- Thrombocytopenia -- Platelet count is often less than 20 x 109/L in TTP, but may not be as low in HUS.
- Schistocytes (red blood cell fragments, as indicated by the arrows in the image to the right) may be observed on the peripheral blood smear. Schistocytes are the result of erythrocytic membrane damage caused by sheering of red blood cells as they pass through a fibrin mesh of clot formation occurring in the blood vessels.
- LDH, serum bilirubin, and reticulocyte counts are elevated.
- Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are usually normal.
- Proteinuria and hematuria may be present.