Haemoglobin is complex protein found in red blood cells that contains an iron molecule. The main function of haemoglobin is to carry oxygen from the lungs to the body tissues, and to exchange the oxygen for carbon dioxide, and then carry the carbon dioxide back to the lungs and where it is exchanged for oxygen. The iron molecule in haemoglobin helps maintain the normal shape of red blood cells.

What does low haemoglobin mean?

Low haemoglobin means that a person's haemoglobin level when measured, is below the lowest limits of normal for their age and sex. For example, an adult male would have low haemoglobin if the detected blood value was below 13.6 g/dl. Another term frequently used in place of low haemoglobin is anaemia. Some of the more common causes of anaemia are as follows:

  • Nutritional (iron, folic acid, or vitamin B12 deficiency)
  • Gastrointestinal blood loss (ulcers, colon cancer)
  • Kidney problems
  • Blood loss (from trauma or surgery)
  • Red Blood cell synthesis problems (bone marrow disorders, genetic disorders such as sickle cell anaemia)
  • Bone marrow suppression by chemotherapy or radiation exposure

What does high haemoglobin mean?

High haemoglobin levels mean that measured haemoglobin levels are above the upper limits of normal for the age and sex of the person. For example, an adult male that has a detected haemoglobin level of above 17.7 g/dl would have a high haemoglobin level. Some causes for high haemoglobin levels are as follows:

  • Living at a high altitude
  • Lung disease
  • Cancer
  • Tobacco smoking
  • Bone marrow disorders
  • Overdose or inappropriate use of the drug Epoetin alfa
  • Blood doping (adding RBC's by IV to the bloodstream)