What is the normal adult hemoglobin composition?

What is the normal adult hemoglobin composition?

• A. More than 90% HbA, 1% HbA2, 5% HbF
• B. More than 95% HbA, less than 3.5% HbA2, less than 1-2% HbF
• C. Less than 90% HbA, 10% HbA2, 5% HbF
• D. More than 90% HbA, 1% HbA2, 5-10% HbF

Answer: (B)

The normal adult hemoglobin composition is characterized primarily by the presence of hemoglobin A (HbA), which constitutes the majority of hemoglobin in healthy adults. Typically, HbA makes up more than 95% of total hemoglobin in the adult population. The minor components include hemoglobin A2 (HbA2) and hemoglobin F (HbF). HbA2 is expected to be less than 3.5%, while HbF is normally found in very small amounts, generally less than 1-2%. This composition reflects the transition from fetal hemoglobin (HbF) to adult hemoglobin (HbA) that occurs as a person ages, leading to higher proportions of HbA and lower amounts of HbF and HbA2 in normal adults. Such a composition is pivotal for appropriate oxygen transport and delivery throughout the body, as HbA has a higher affinity for oxygen compared to HbF. The other options do not accurately represent the normal adult hemoglobin composition, either overstating the levels of other hemoglobin types or misrepresenting the normal range for HbA. It's critical to understand these percentages to appreciate the physiological role of hemoglobin in adults.

The normal adult hemoglobin composition is characterized primarily by the presence of hemoglobin A (HbA), which constitutes the majority of hemoglobin in healthy adults. Typically, HbA makes up more than 95% of total hemoglobin in the adult population. The minor components include hemoglobin A2 (HbA2) and hemoglobin F (HbF). HbA2 is expected to be less than 3.5%, while HbF is normally found in very small amounts, generally less than 1-2%.

This composition reflects the transition from fetal hemoglobin (HbF) to adult hemoglobin (HbA) that occurs as a person ages, leading to higher proportions of HbA and lower amounts of HbF and HbA2 in normal adults. Such a composition is pivotal for appropriate oxygen transport and delivery throughout the body, as HbA has a higher affinity for oxygen compared to HbF.

The other options do not accurately represent the normal adult hemoglobin composition, either overstating the levels of other hemoglobin types or misrepresenting the normal range for HbA. It's critical to understand these percentages to appreciate the physiological role of hemoglobin in adults.