Which statement is true about Haemoglobin F (HbF)?

Which statement is true about Haemoglobin F (HbF)?

• A. It persists unchanged throughout adulthood.
• B. It is the main adult haemoglobin.
• C. It is foetal haemoglobin and is replaced by HgbA shortly after birth.
• D. It binds carbon dioxide more efficiently than HgbA.

Answer: (C)

HbF is the fetal form of hemoglobin produced during fetal life, made with gamma chains. Its key property is a higher affinity for oxygen, which helps the fetus extract oxygen from the mother’s blood across the placenta. After birth, the body switches to producing adult hemoglobin (HbA, with alpha and beta chains), and HbF levels fall rapidly. By several months of life, HbA becomes the predominant form, with only small amounts of HbF remaining. This is why the statement describing HbF as the foetal form and noting that it is replaced by HbA shortly after birth is true. The other statements don’t fit because HbF does not persist unchanged into adulthood, it is not the main adult hemoglobin, and its defining difference isn’t that it binds carbon dioxide more efficiently than HbA.

HbF is the fetal form of hemoglobin produced during fetal life, made with gamma chains. Its key property is a higher affinity for oxygen, which helps the fetus extract oxygen from the mother’s blood across the placenta. After birth, the body switches to producing adult hemoglobin (HbA, with alpha and beta chains), and HbF levels fall rapidly. By several months of life, HbA becomes the predominant form, with only small amounts of HbF remaining. This is why the statement describing HbF as the foetal form and noting that it is replaced by HbA shortly after birth is true.

The other statements don’t fit because HbF does not persist unchanged into adulthood, it is not the main adult hemoglobin, and its defining difference isn’t that it binds carbon dioxide more efficiently than HbA.