A 23-year-old man of nohern European lineage presents with anemia. His father and paternal aunt had a similar illness that was treated successfully by splenectomy. His peripheral blood smear is similar to that shown in the illustration. Which of the following additional abnormalities is expected?

- Spherocytes are present in given peripheral smear; along with the history, strongly suggests diagnosis of hereditary spherocytosis. - Similar cells are also observed in warm antibody autoimmune hemolytic anemia. - These two conditions can be distinguished by direct Coombs test, which is negative in hereditary spherocytosis & positive in warm antibody autoimmune hemolytic anemia. - An expected finding in HS is increase in indirect (unconjugated) serum bilirubin, not direct (conjugated). - Polychromatophilic erythrocytes are an expected finding, as in any hemolytic anemia.