Anaemia

What is anaemia?

Anaemia is a condition where the blood lacks enough healthy red blood cells or haemoglobin, leading to reduced oxygen delivery to the body's tissues. This can result in symptoms like fatigue, weakness, shortness of breath and pale or yellowish skin. The severity of anaemia can vary from mild to severe and may affect individuals of all ages.

What are the different types of anaemia?

Anaemia can be classified based on its underlying causes, which are generally grouped into three categories:

Reduced production of red cells

• Iron deficiency anaemia: This is the most common type and occurs when your body doesn't have enough iron to produce haemoglobin. It can result from poor diet, chronic blood loss (such as heavy periods or ulcers) or certain chronic diseases.

• Vitamin deficiency anaemia: This type occurs when the body lacks essential vitamins like B12 or folate, which are crucial for producing red blood cells. For example, pernicious anaemia is caused by the body's inability to absorb vitamin B12 properly.

• Anaemia of chronic disease: Chronic illnesses such as kidney disease or chronic infections can impair the body's ability to produce enough red blood cells.

Increased red cell destruction or breakdown

• Haemolytic anaemia: Occurs when red blood cells are destroyed faster than the bone marrow can replace them. Causes include autoimmune diseases, inherited disorders like sickle cell anaemia or reactions to certain medications.

• Sickle cell anaemia: A genetic disorder where red blood cells are abnormally shaped, causing blockages in blood flow, pain and other complications.

Blood loss

• Acute blood loss anaemia: Results from a sudden and significant blood loss, such as from injury or surgery, leading to a rapid decrease in red blood cells.

• Chronic blood loss anaemia: Results from long-term, slow bleeding, often due to conditions like ulcers or heavy menstrual periods, which gradually deplete the body's iron stores.

What are the symptoms of anaemia?

Anaemia often presents with a variety of symptoms, which can differ depending on the severity and underlying cause of the condition. Common symptoms include:

What causes of anemia?

Anaemia can arise from a range of causes, typically grouped into:

• Iron deficiency
  
• Folate and vitamin B12 deficiency
  
• Inflammation
  
• Bone marrow underproducing
  
• Malignant bone marrow disorders (e.g. myelodysplastic syndrome, leukemia, myelofibrosis)
  
•  Increased red blood cell breakdown
  
• Thalassemia
  
  

How is anaemia treated?

The treatment for anaemia is tailored to address its underlying cause. A haematologist will evaluate the patient to determine the specific cause of the anaemia and recommend appropriate treatment options. Depending on the diagnosis, the following treatments may be considered:

• Transfusion or red blood cells
• Infusions of iron
• Hormonal injections to boost red cell production
  
• Replacement of iron or vitamins and dietary advice
• Immunosuppressive medication to control an immune system that is destroying red blood cells

For anaemia due to blood cancers such as leukemias, myelomas, lymphomas or myelodysplastic syndrome, dedicated teams in the blood cancer service will assess and plan treatment with chemotherapy, immunotherapy or haematopoietic stem cell transplant as needed.

Is anaemia that is caused by blood loss more life-threatening?

• It depends on the rate and volume of blood loss and the fitness of the individual. Sudden, rapid and ongoing blood loss can be life-threatening.
• If blood loss is slow and over a long period of time (eg. over a few months), the patient may not even experience any symptoms until the blood level has dropped considerably.
• Anaemia that causes a sudden rapid drop in red blood cells, such as haemolytic anaemia (red blood cell breakdown) can also be life threatening as there is no time for the body to compensate.  There is no one cause of anaemia that is more life threatening than another. The cause needs to be identified early such that treatment can stop the blood loss and supportive transfusions can be given in the meantime.  

How common is anaemia in Singapore?

• In a study (Sahadevan et al. 1995) of hospitalized patients above 65 years of age, about 1 in 3 patients (35.8%) were found to be anemic. More males (55.6%) than females (44.4%) have anaemia.
• In the younger age group, iron deficiency anaemia is more common in females than males. Iron deficiency anaemia in younger females is mainly due to excessive menstrual loss with inadequate iron replacement which may go untreated or undetected.
• Anaemia is a World Bank development indicator. In 2016, it was reported that 22% of non-pregnant women between the ages of 15-49 had anaemia in Singapore. Among pregnant women, 31% had anaemia. 

Who is more prone to anaemia and why?

• Causes of anaemia are wide ranging and there are several groups that are more prone to have anaemia. In women who have their menses, iron deficiency anaemia is common. In pregnant women, anaemia can occur due to dietary deficiencies and increased blood volume.
• In older patients with multiple medical problems or kidney disease, there is underproduction of red blood cells by the bone marrow due to inflammation, suppression, or lack of erythropoietin (which is a hormone produced by the kidneys to stimulate red blood cell production).
• Patients with malignancies may have anaemia due to the disease or due to medications that suppress the bone marrow.
• A common inherited anaemia in Singapore is thalassemia where abnormal production of haemoglobin results in anaemia. About 4% of our population are carriers of the thalassemia gene.  A large proportion have thalassemia minor (thalassemia trait) with mild or undetectable anaemia and can lead a normal life. A small proportion have thalassemia major or intermedia that require blood transfusion. The risk of thalassemia major increases when both parents are carriers of the thalassemia gene. Therefore, screening is recommended for couples that are planning to start a family.