RT Journal A1 MENGEL CE, WALLACE AG, McDANIEL HG T1 INfectious mononucleosis, hemolysis, and megaloblastic arrest JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1964 FD September 1 VO 114 IS 3 SP 333 OP 335 DO 10.1001/archinte.1964.03860090067004 UL http://dx.doi.org/10.1001/archinte.1964.03860090067004 AB Introduction  Acute hemolytic anemia with hemoglobinuria is an unusual complication of infectious mononucleosis.1-18 It is most often secondary to the production of high titers of cold agglutinins and hemolysins and usually occurs between the second and third week of illness.19,20 Aregenerative crises have occurred during the course of certain chronic hemolytic anemias and have been considered to result from "relative folie acid deficiency."21-23 The patient described here illustrated the development of megaloblastic marrow arrest during an acute episode of massive hemolysis associated with infectious mononucleosis.Report of a Case  A 15-year-old white schoolboy entered the hospital complaining of weakness and fever. Except for the usual childhood diseases, he had been in excellent health until this illness. Three weeks prior to admission he developed a nonproductive eough, coryza, and malaise without fever. Despite persistent fatigue, he went on a camping trip two weeks prior to admission. Generalized malaise increased and he