A 32-year-old woman is evaluated in the emergency department for a 3-day history of worsening fatigue, generalized weakness, and intermittent episodes of confusion. She has no significant past medical history and takes no medications. Her temperature is 37.8°C (100.0°F), blood pressure is 142/86 mm Hg, heart rate is 105/min, and respiratory rate is 18/min. Physical examination is notable for scattered petechiae over her lower extremities and mild scleral icterus. Neurological examination reveals mild disorientation but no focal deficits.
Laboratory results are as follows:
| Test | Result |
|---|---|
| Hemoglobin | 8.4 g/dL |
| Platelet count | 22,000/mm³ |
| Leukocyte count | 8,500/mm³ |
| Creatinine | 1.6 mg/dL |
| Total bilirubin | 3.2 mg/dL |
| Indirect bilirubin | 2.8 mg/dL |
| Lactate dehydrogenase | 950 U/L |
| Prothrombin time (PT) | 12 seconds |
| Activated partial thromboplastin time (aPTT) | 30 seconds |
A peripheral blood smear demonstrates numerous fragmented red blood cells. Which of the following best describes the underlying molecular mechanism responsible for this patient's condition?
- Failure to cleave ultra-large von Willebrand factor multimersCevap
- BUnregulated systemic activation of the coagulation cascade and fibrinolysis
- CAutoantibody-mediated clearance of circulating platelets by splenic macrophages
- DDecreased stabilization of factor VIII and impaired primary hemostasis
- EAbsence of glycosylphosphatidylinositol-anchored complement inhibitors on cell membranes