It can be due to a reduction in the number of red cells, which may be the result of decreased production or increased destruction or both. It can also be due to abnormally formed haemoglobin and abnormal red cells which affect the stability of the red cells making them more prone to be destroyed.

Blood consists of three types of blood cells:

• White blood cells are cells that fight infection.
  
• Platelets help the blood to clot.
  
• Red blood cells carry oxygen from the lungs in the blood to the vital organs and other tissues.
  

Red blood cells contain hemoglobin, an iron-containing protein that gives blood its red color.

In anaemia, the body produces fewer red blood cells, loses too many of them or these cells are destroyed more quickly than they can be replaced.

Types of Anaemia

Common types of anaemia include:

• Iron deficiency anaemia is the most common form of anaemia that is caused by a deficiency of iron in the body.
  
• Vitamin B12 and folate deficiency anemia is also called megaloblastic anaemia.
  
• Anaemia of chronic disease may be due to cancer, kidney failure, rheumatoid arthritis, Crohn's disease and other chronic inflammatory diseases which interfere with the production of red blood cells.
  
• Aplastic anaemia is a life-threatening anaemia caused by a decrease in the bone marrow's ability to produce red blood cells, white blood cells and platelets.
  
• Anaemia associated with bone marrow diseases such as leukemia.
  
• Hemolytic anaemia develops when red blood cells are destroyed.
  
• Sickle cell anaemia is an inherited anaemia which is caused by a defective form of haemoglobin that forces red blood cells to assume an abnormal crescent (sickle).

Symptoms

Anaemia in its early stage may not have any specific symptoms and the main symptom may just be fatigue.

Other symptoms may include:

• Pale skin
  
• A fast or irregular heartbeat
  
• Shortness of breath
  
• Chest pain
  
• Dizziness
  
• Cognitive problems
  
• Numbness or coldness in your extremities
  
• Headache
  
• Yellowing of the skin in anaemia due to increased red cell destruction
  

Risk factors

These factors include:

• Poor diet consistently low in iron and vitamins such as folate which increase the risk of developing anaemia.
  
• Intestinal disorders that affect the absorption of nutrients in the small intestine such as Crohn's disease and Celiac disease.
  
• Menstrual disorders with increased blood loss. Women are at greater risk of iron deficiency anaemia because women lose blood during periods especially those with heavy blood loss during periods.
  
• Pregnancy increases the risk of iron deficiency anaemia because of increased blood volume during pregnancy well as increasing demands from the growing fetus.
  
• Chronic conditions like cancer, kidney or liver failure, rheumatoid arthritis increase the risk of developing anaemia of chronic disease.
  
• Family history of inherited anaemia also increases the risk of developing anaemia.
  

Diagnosis of Anaemia

Anaemia is diagnosed based on:

• medical history
  
• physical examination
  
• blood tests such as peripheral smear and full blood count (FBC) and other blood indices
  
• bone marrow biopsy to confirm the diagnosis in more difficult cases
  

Treatment

The treatment of anaemia depends on the cause:

• Iron deficiency anaemia is treated with iron supplements. In severe cases, a blood transfusion may be necessary.​
  
• Vitamin deficiency anaemia such as Pernicious anaemia is treated with Vitamin B-12 injections and folic acid deficiency anaemia is treated with folic acid supplements.
  
• Anaemia of chronic disease has no specific treatment for anaemia as iron supplements and vitamins are generally not helpful. If the symptoms are severe, a blood transfusion may be required.
  
• Aplastic anaemia treatment may include blood transfusions to boost levels of red blood cells or a bone marrow transplant.
  
• Hemolytic anaemia treatment includes taking drugs that suppress the immune system such as steroids or gamma globulin. If the spleen is enlarged, the spleen may need to be removed.
  
• Sickle cell anaemia treatment includes blood transfusions, folic acid supplements, antibiotics, bone marrow transplant and cancer drugs such hydroxyurea in adults.
  

Prevention

1. Avoid iron deficiency anaemia and vitamin deficiency anaemia by eating a healthy diet that includes foods rich in iron, folate and vitamin B-12.

   The best sources of iron are:

   • beef and other red meats
   • beans
   • lentils
   • iron-fortified cereals
   • dark green leafy vegetables​
   • dried fruit
   • nuts and seeds
   
   
   ​​​​Folate can be found in citrus juices and fruits, dark green leafy vegetables, legumes and fortified breakfast cereals. Vitamin B-12 is plentiful in meat and dairy products.
   
   ​​
   
2. Take iron supplements for iron deficiency anaemia as recommended by your doctor.
   ​

3. Vegans can consume non-haem sources of iron such as green leafy vegetables and fruits rich in Vitamin C to maximise their iron absorption. They can also get alternative sources of iron from beans (eg, bean products such as soy beans, tempeh, lentils, tofu, chickpeas), whole-grains, nuts and seeds.

   Even then, it may not be enough especially for women, whose recommended RDA for iron is 19mg. Vegans should talk to their doctors about iron supplements if they suspect they may be lacking the nutrient.