What is the best diagnosis for the following patient?
A 49-year-old female presents with signs of anemia and states that every morning her urine is dark. Work-up reveals that her RBCs lyse in vitro with acid (positive Ham’s test).
A. Warm, autoimmune hemolytic anemia
B. Paroxysmal nocturnal hemoglobinuria
C. Cold-agglutinin autoimmune hemolytic anemia
D. G6PD deficiency
Paroxysmal nocturnal hemoglobinuria-b) paroxysmal nocturnal hemoglobinuria (pnh) is an acquired clonal stem cell disorder that is characterized by abnormal red cells, granulocytes and platelets. the rbcs are abnormally sensitive to the lytic activity of complement due to a deficiency of gpi linked proteins, namely decay accelerating factor (daf; or cd55), membrane inhibitor of reactive lysis (cd55) or cd59 (a c8 binding protein). complement is normally activated by acidotic states, such as occur with exercise or sleep. in patients with pnh, the acidotic condition that develops during sleep ( which is usually at night) causes hemolysis of red cells and results in red urine in the morning. the rbcs of these patients lyse in vitrowith acid (sucrose lysis test).a positive coombs test suggests immune-related hemolysis.