What is Haemoglobin (Hb)?

About Haemoglobin (Hb):

• It is an iron-containing protein found in the red blood cells that carries oxygen from the lungs to the body's tissues and returns carbon dioxide from the tissues back to the lungs.
• It is made up of four protein molecules (globulin chains) that are connected together.
• Haemoglobin forms an unstable, reversible bond with oxygen. In the oxygenated state, it is called oxyhemoglobin and is bright red; in the reduced state, it is purplish blue.
• It also plays an important role in maintaining the shape of the RBCs. In their natural shape, RBCs are round with narrow centers resembling a donut without a hole in the middle. Abnormal haemoglobin structure can, therefore, disrupt the shape of RBCs and impede their function and flow through blood vessels.
• Haemoglobin levels vary from person to person. Men usually have higher levels than women.
• What does a low haemoglobin level mean?
  • A low haemoglobin level is referred to as anemia or low red blood count. 
  • A lower than normal number of RBCs is referred to as anemia and haemoglobin levels reflect this number.
  • Some of the more common causes of anemia are:
    • loss of blood (traumatic injury, surgery, bleeding, colon cancer, or stomach ulcer),
    • nutritional deficiency (iron, vitamin B12, folate),
    • bone marrow problems (replacement of bone marrow by cancer),
    • suppression by red blood cell synthesis by chemotherapy drugs,
    • kidney failure, and
    • abnormal haemoglobin structure (sickle cell anemia or thalassemia).