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A 30-year-old female patient is seen for evaluation of fatigue. Initial labs show a hemo globin of 7.6 g/dl, MCV of 106 FL. WBC of 3,200/,LLL. and platelets of 178.000/,LLL. LDH is 1 .200 U/L and haptoglobin is low. On review of symptoms, she states that her urine is dark in the morning, but clears toward the evening. Test tubes showing serial urine samples are shown below.
Which of the following tests would most likely lead to a definitive diagnosis in this patient?
- Cytogenetic analysis of a bone marrow aspirate
- Direct antigen test
- Flow cytometry of peripheral blood
- Complement levels
- Urine protein electrophoresis
Medicine
C. The urine demonstrates early morning hemoglobinuria, which clears during the day. This observation in a patient with evidence of hemolysis (increased LDH and decreased haptoglobin) should raise concern for paroxysmal nocturnal hemoglobinuria (PNH). Hemolytic anemia in PNH is due to increased sensitivity to complement lysis secondary to deficiency of CD 55 (decay accelerating factor) and CD 59 (membrane inhibitor of reactive lysis). Flow cytometry can detect decreased expres sion of these complement proteins and is a standard test used in the diagnosis of PNH.
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