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Chapter 35: Thrombotic Microangiopathies

A 47-year-old woman is admitted with weakness and fevers. Laboratory testing reveals a hemoglobin level of 7.4 g/dL and a platelet count of 20,000/μL. Further testing reveals a serum creatinine of 1.5 mg/dL and proteinuria (1+ by dipstick testing). Her medical history is otherwise unremarkable and she is not on any medications. Blood and urine cultures are sent.

Which ONE of the following should be done next?

A. Transfusion of packed red blood cells and platelets while awaiting blood culture results.

B. Treatment with corticosteroids and rituximab.

C. ADAMTS13 activity should be measured, and the patient should be empirically treated with plasma exchange while awaiting the results.

D. The patient should be started on captopril, and the dose should be titrated to achieve a blood pressure of less than 140/80 mm Hg.

E. Computed tomography and bone marrow biopsy should be performed to look for an occult tumor.

The answer is D. This patient’s findings are consistent with thrombotic thrombocytopenic purpura. ADAMTS13 activity should be measured in a sample collected prior to plasma exchange, but treatment with plasma exchange should not be delayed while awaiting the results. Corticosteroids may be beneficial, but rituximab can be reserved for patients with refractory or recurrent disease. Alternative diagnoses should be considered, including autoimmune disease, infections, and cancer. Transfusion of packed red blood cells or platelets can be performed if necessary, but should not be undertaken based on lab values.

A 15-year-old girl is admitted with a 1-day history of anuria and anasarca. Her serum creatinine is 5.4 mg/dL, her hemoglobin level is 8 g/dL, and the platelet count is 50,000/μL. Testing for Shiga-like toxin is negative and ADAMTS13 activity is 30%. A presumptive diagnosis is atypical hemolytic uremic syndrome is made, and treatment with the complement inhibitor eculizumab is planned.

Which ONE of the following should be done next?

A. A renal biopsy should be performed to confirm the diagnosis.

B. The patient should empirically be treated with corticosteroids and plasma exchange.

C. The patient should be tested for systemic lupus erythematosus, and corticosteroids should be empirically started while awaiting the results.

D. The patient should be empirically treated with ciprofloxacin for a possible asymptomatic enteric infection.

E. The patient should be immunized for meningococcus and empirically treated to cover meningococcal infection for 2 weeks.

The answer is E. Treatment with eculizumab increases the risk ...

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