Review Question - QID 106270

The patient presents with signs and symptoms of thrombotic thrombocytopenic purpura (TTP). The vWF metalloprotease ADAMTS13 is deficient in TTP, leading to decreased degradation of vWF multimers and subsequent clotting disorders due to a deficiency of available vWF.

Patients presenting with thrombocytopenia and microangiopathic hemolytic anemia should be admitted to the hospital with a presumptive diagnosis of TTP. Signs and symptoms include fever, neurological symptoms and mental status changes, renal impairment, and thrombocytopenia. Labs may also show prolonged bleeding time and evidence of hemolytic anemia such as elevated bilirubin and LDH.

Gauer and Braun review thrombocytopenia. TTP is relatively rare with an incidence of 4-11 patients per million annually in the United States. The absence or deficiency of a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13) is thought to cause the disorder. Treatment for TTP is plasma exchange. Since TTP is fatal without treatment, prompt initiation of therapy is critical.

Lotta et al. review ADAMTS13 activity in TTP. TTP is a clinically heterogenous disease. Developments that have allowed researchers to measure ADAMTS13 activity have demonstrated a relationship between levels of ADAMTS13 activity below 10% and the clinical manifestations of TTP. Residual activity of ADAMTS13 may be a major determinant of disease severity and outcome in TTP.

Figure A shows schistocytes, or helmet cells, on peripheral blood smear. Schistocytes are a characteristic finding in microangiopathic anemia.
Illustration A shows renal changes in TTP. A thrombus is present in the hilum of the glomerulus at the center of the image.

Incorrect Answers:
Answer 1: Platelet aggregation defects are seen in Glanzmann's thrombasthenia, a rare platelet disorder. Blood smear shows a lack of platelet clumping.
Answer 3: Antibody-mediated peripheral platelet destruction occurs in idiopathic thrombocytopenic purpura (ITP). ITP does not cause fever, renal impairment, or neurologic changes.
Answer 4: Defect in platelet-to-collagen adhesion is seen in Bernard-Soulier disease, an autosomal recessive bleeding disorder. Renal impairment and neurologic symptoms are not seen.
Answer 5: Decreased levels of vWF cause von Willebrand's disease, an autosomal dominant bleeding disorder. Renal impairment and neurologic symptoms are not present in von Willebrand's disease.