A 25-year-old woman comes to the hospital because of abdominal pain, yellowish discoloration of the skin and eyes, and fatigue. She has a recurrent episodes of reddish discoloration of her urine over the past year. Physical examination shows pallor and scleral icterus. The spleen is not palpable. Her hemoglobin concentration is 7.8 g/dL, leukocyte count is 2,000/mm3, and platelet count is 80,000/mm3. Serum LDH and unconjugated bilirubin concentrations are elevated. Addition of a serum containing anti-human globulins to a blood sample shows no agglutination. A urine dipstick shows blood; urinalysis shows no RBCs. A CT scan of the abdomen shows a thrombus in a hepatic vein thrombosis. Which of the following is the most likely cause of this patient's anemia?

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Quizplus · Accepted Answer

Eductional Objective: The triad of hemolytic anemia, hypercoagulability, and pancytopenia suggests paroxysmal nocturnal hemoglobinuria (PNH).  PNH results from an acquired mutation in the PIGA gene that causes absence of the glycosylphosphatidylinositol anchor and associated deficiency of CD55 and CD59 complement inhibitor proteins.

A 25-Year-Old Woman Comes to the Hospital Because of Abdominal