Final answer:
Madison Cawein suspected methemoglobinemia, a condition distinguished by high methemoglobin levels, different from sickle cell anemia or thalassemia which affect hemoglobin's shape or production, respectively.
Step-by-step explanation:
Madison Cawein, a hematologist, suspected the rare hereditary blood disorder that results in excess levels of methemoglobin in the blood to be methemoglobinemia. This condition is characterized by an abnormally high level of methemoglobin, which is a form of hemoglobin that is unable to release oxygen effectively to body tissues. It's distinguished from other hematologic disorders like sickle cell anemia, which involves abnormally shaped red blood cells that can lead to blockages in blood vessels and reduced oxygen delivery, and thalassemia, which is caused by a defect in the hemoglobin subunits leading to ineffective oxygen transport and anemia. Neither sickle cell anemia nor thalassemia are associated with the high levels of methemoglobin found in methemoglobinemia.