Which type of hemoglobin is not normally found in adults?

In adults, hemoglobin type Hb-F (fetal hemoglobin) is typically present in small amounts due to its function during fetal development, while Hb-A (the primary adult hemoglobin) accounts for the majority of hemoglobin found in adults. Hb-S (sickle hemoglobin) and Hb-C are abnormal hemoglobins that can be present in specific populations or in individuals with certain hemoglobinopathies.

The primary reason Hb-S is considered the correct answer is that it is not normally present in a healthy adult population. Instead, Hb-S is a variant associated with sickle cell disease and is typically found in individuals who have inherited the trait from parents who are carriers or those who are affected by the disease itself. While Hb-S does appear in certain ethnic groups, it is not part of the normal adult hemoglobin spectrum.

In summary, Hb-S is not a normal component of adult hemoglobin, as it is primarily associated with disease states, marking it distinct from the other hemoglobins mentioned, which may either be present in low concentrations or represent variations of normal hemoglobin.