Paroxysmal Nocturnal Hemoglobinuria with Elevated Fetal Hemoglobin

A persistent elevation of the fetal hemoglobin (Hgb F) level (5%-15%) was observed in a 22-yr-old white male with paroxysmal nocturnal hemoglobinuria (PNH). Acid treatment of the peripheral smear (Betke-Kleihauer technique) demonstrated a heterogeneous distribution of Hgb F in the red cells. As expected, the lowest acetylcholinesterase activity and the most hemolysis after acid stress were found in the low-density, reticulocyte-rich cell fraction. In contrast, the highest Hgb F levels were found in the high-density, reticulocyte-poor fraction. Further evidence for the segregation of these two abnormalties was obtained from the observation that less Hgb F was present in the hemolysate obtained after acid lysis than was present in the mixed blood sample or the remaining nonhemolyzed red cells.