We have all got our haemoglobin levels checked at least once in our lives. Haemoglobin is an essential part of red blood cells (RBCs) which transport oxygen to the entire body. Heme is the part of haemoglobin that binds with oxygen and globin is the protein that surrounds and protects heme. The normal concentration of haemoglobin in an adult is around 14 to 18 grams per deciliter of blood in men and 12 to 16 grams per deciliter of blood in women.
The RBC is an oval-shaped biconcave disc which contains haemoglobin - for this reason, the RBC is also known as the sac of haemoglobin. The percentage of haemoglobin in a single red blood cell is around 33%.
Our blood gets 97% of its oxygen from the lungs and the remaining 3% gets absorbed in the plasma. Haemoglobin enables the blood to carry 30 to 100 times more oxygen than would have been possible if the body were to transport oxygen only through plasma. When the blood reaches the lungs, the haemoglobin present in the blood binds with oxygen molecules and releases it into the blood capillaries. The blood capillaries then pass the oxygen on to different parts.
Each molecule of haemoglobin contains four atoms of iron. Each iron atom binds with one molecule of oxygen. Also, iron is responsible for giving blood its red colour. Whenever there is a deficiency of iron in the body, the production of heme gets hampered. This causes the levels of haemoglobin to go down.
Here's what you need to know about the functions and normal limits of haemoglobin in a person’s body:
Haemoglobin function
There are two main functions of haemoglobin in the body:
- Haemoglobin carries oxygen in the blood.
- Haemoglobin helps in maintaining the shape of the red blood cells.
In addition to this, haemoglobin is responsible for the red colour of blood. When the liver breaks down old red blood cells, the haemoglobin in them degrades to iron, globin protein and bilirubin. This bilirubin is responsible for the yellow colour of faeces.
Normal haemoglobin levels
The amount of haemoglobin is measured per 100 millilitres of blood. Clinically, haemoglobin is measured in decilitres (dl) which is equivalent to 100 ml. The levels of haemoglobin vary at different stages of life. The levels are found to be different for men, women and children. As per laboratory testing, the normal limits of haemoglobin are:
Age | Normal limits (per 100ml of blood) |
Newborn | 17-22 gm/100 ml |
1-week old infant | 15-20 gm/100 ml |
1-month old infant | 11-15 gm/100 ml |
Children | 11-13 gm/100 ml |
Adult male | 14-18 gm/100 ml |
Adult female | 12-16 gm/100 ml |
Middle-aged males | 12.4-14.9 gm/100 ml |
Middle-aged females | 11.7-13.8 gm/100 ml |
Causes of high haemoglobin
People who live at high altitudes or smoke on a regular basis tend to have an unusually high haemoglobin level. There are also certain medical conditions in which the levels of haemoglobin increases to unusual limits:
- Polycythemia vera: Polycythemia vera is a condition where the bone marrow starts producing a large number of red blood cells. Once the levels of RBCs rise, the haemoglobin levels spike simultaneously.
- Kidney tumour: Many people with kidney cancer have shown an unexplained hike in their haemoglobin.
- Lung diseases: Haemoglobin levels can rise in some lung diseases like chronic obstructive pulmonary disease (COPD), emphysema and pulmonary fibrosis.
- Dehydration: The levels of haemoglobin spike in a person with dehydration, but settle down as soon as the body gets hydrated.
- Hypoxia: As soon the body gets hypoxic (lack of oxygen), the body starts producing more red blood cells, to compensate for the loss. This spikes the haemoglobin levels in the blood.
- Drugs: People who take anabolic steroids like synthetic testosterone would have high levels of haemoglobin in their blood.
Causes of low haemoglobin
People with low haemoglobin would present with anaemia. Low haemoglobin can occur in cases of heavy bleeding, conditions in which the body makes fewer than normal red blood cells and diseases in which the body destroys red blood cells prematurely. Some of these conditions include:
- Aplastic anemia
- Different types of cancer that affect the blood such as Non-Hodgkin's Lymphoma and multiple myloma and leukemia.
- Chronic kidney disease
- Liver disease, including liver cirrhosis: the liver is responsible for breaking down old red blood cells. A problem with this mechanism could affect the amount of haemoglobin in the blood.
- Hypothyroidism: people with an underactive thyroid gland may produce fewer red blood cells.
- Porphyria: People with this condition have inadequate quantities of certain enzymes needed to make heme in the body.
- Sickle cell disease: The red blood cells of people with this condition live up 20 days compared with 90-120 days normally.
- Thalassemia: A genetic condition in which the red blood cells are destroyed too quickly.
- Vasculitis: inflammation of the blood vessels
- Heavy periods (menorrhagia)