A 45-year-old previously healthy man is brought to the emergency department due to headaches and confusion for 2 days. He has no focal weakness or sensory symptoms. The patient has no significant past medical history and does not take any medications. He does not use tobacco, alcohol, or illicit drugs. Temperature is 37.9 C (100.2 F), blood pressure is 140/86 mm Hg, pulse is 96/min, and respirations are 16/min. Mild icterus is present. His neck is supple and without rigidity. Cardiopulmonary and abdominal examinations are normal. Neurologic examination shows no focal deficits. Laboratory results are as follows: A peripheral blood smear shows many fragmented red blood cells. The prothrombin time is normal. Which of the following is the most appropriate next step in the management of this patient?

Question

A 45-year-old previously healthy man is brought to the emergency department due to headaches and confusion for 2 days.  He has no focal weakness or sensory symptoms.  The patient has no significant past medical history and does not take any medications.  He does not use tobacco, alcohol, or illicit drugs. Temperature is 37.9 C (100.2 F), blood pressure is 140/86 mm Hg, pulse is 96/min, and respirations are 16/min.  Mild icterus is present.  His neck is supple and without rigidity.  Cardiopulmonary and abdominal examinations are normal.  Neurologic examination shows no focal deficits.  Laboratory results are as follows:  A peripheral blood smear shows many fragmented red blood cells.  The prothrombin time is normal.  Which of the following is the most appropriate next step in the management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d431_4bd5_bc81_55703831187b_MD0003_00 Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder of the microvasculature characterized by the formation of small vessel thrombi that consume platelets, shear red blood cells, and cause end organ damage. Classically, TTP is marked by the pentad of: Thrombocytopenia Microangiopathic hemolytic anemia (MAHA) Renal insufficiency Neurologic changes (eg, headache, confusion, coma, stroke) Fever TTP is caused by a deficiency of plasma protease ADAMTS13 (due to the formation of an autoantibody). In the absence of this protease, long chains of von Willebrand factor accumulate on the endothelial wall, trapping platelets and generating thrombi in areas of high shearing force (eg, arterioles, capillaries). The diagnosis is based largely on clinical and laboratory findings; evidence of MAHA on peripheral blood smear (schistocytes/red blood cell fragments) is an important diagnostic finding. Laboratory markers of coagulation (eg, prothrombin time [PT]) are normal in TTP (unlike in disseminated intravascular coagulation [DIC]). TTP is life threatening and must be treated emergently with plasma exchange (PEX). PEX removes the patient's plasma and replaces it with donor plasma. This replenishes ADAMTS13 and removes the autoantibodies. Without emergent PEX, the mortality rate is approximately 90%. TTP is closely related to hemolytic uremic syndrome (HUS). Both cause MAHA and thrombocytopenia. Unlike TTP, HUS is typically associated with Escherichia coli O157:H7 and is primarily a disorder of the renal system; neurologic findings and fever are uncommon. (Choice A) Cryoprecipitate contains clotting factors, fibrinogen, and von Willebrand factor. It is often used in patients with DIC. This patient's PT is normal, making DIC unlikely. (Choice B) This patient's renal insufficiency is mild. Hemodialysis would not be required. (Choice C) This patient has headache and confusion but no focal neurologic deficits. If there was concern for intracranial bleeding (given thrombocytopenia), a noncontrast head CT scan could be ordered. MRI of the brain is expensive and time consuming, and it would not be a useful next step. (Choices D and H) Red blood cell transfusions are considered for life-threatening bleeding or a hemoglobin <7 g/dL (and possibly higher in patients with coronary artery disease). (Choice F) There is nothing that suggests this patient has severe bleeding. Platelets should not be transfused in TTP unless an invasive procedure or significant bleeding occurs. (Choice G) Urine drug screens are often useful in patients with confusion. However, given this patient's anemia, thrombocytopenia, and evidence of intravascular hemolysis, TTP is likely. Emergent PEX is necessary. Educational objective: Thrombotic thrombocytopenic purpura (TTP) is caused by autoantibodies to plasma protease ADAMTS13 and is marked by microangiopathic hemolytic anemia and thrombocytopenia. TTP is life threatening and requires emergent treatment with plasma exchange.

A 45-Year-Old Previously Healthy Man Is Brought to the Emergency