Paroxysmal nocturnal hemoglobinuria with elevated fetal hemoglobin.

A persistent elevation of the fetal hemoglobin in the low-density, reticulocyte-rich cell frac(Hgb F) level (5%-15%) was observed in a tion. In contrast, the highest Hgb F levels were 22-yr-old white male with paroxysmal nocfound in the high-density, reticulocyte-poor turnal hemoglobinuria (PNH). Acid treatment fraction. Further evidence for the segregation of the peripheral smear (Betke-Kleihauer techof these two abnormalties was obtained from nique) demonstrated a heterogeneous distributhe observation that less 11gb F was present in tion of Hgb F in the red cells. As expected, the the hemolysate obtained after acid lysis than lowest acetylcholinesterase activity and the was present in the mixed blood sample or the most hemolysis after acid stress were found remaining nonhemolyzed red cells.