Eosinophilia


What is it about ?

Blood is made up of a liquid part, plasma. Plasma is responsible for transporting nutrients and blood cells (red blood cells, white blood cells and platelets). White blood cells (also called leukocytes) play an important role in our body’s defense mechanism. They are divided into three main groups: lymphocytes, monocytes and granulocytes. Granulocytes in turn are made up of neutrophils (important in fighting infections), basophils (their function is poorly understood, but is for example greatly increased in a certain type of blood cancer) and eosinophils.

We have three types of cells in our blood: red blood cells, white blood cells, and platelets. These cells all have a different function.

White blood cells play an important role in our immune system. If our body has to defend itself against intruders (viruses, bacteria or parasites), it makes more white blood cells. Leukocytosis is the increase in the total number of white blood cells.

There are different kinds of white blood cells. The main ones are neutrophils and lymphocytes. Eosinophils make up 1-5% of the total number of white blood cells. They contribute to the defense of our body against a large number of diseases.

We speak of eosinophilia when the amount of eosinophils in the blood is greater than normal. The number of eosinophils can vary; the rate is higher in the evening, during menstruation and during physical exertion, and lower in the morning or under the influence of certain drugs (beta blockers) and stress.

Eosinophilia can have many causes:

  • allergic diseases (asthma and hay fever),
  • parasitic infections (worms, toxoplasmosis),
  • medicines (some antibiotics),
  • toxic substances (tryptophan),
  • skin diseases (eczema or psoriasis),
  • lung problems (pneumonia),
  • connective tissue diseases (eg severe rheumatoid arthritis);
  • gastrointestinal diseases (celiac disease or gluten intolerance),
  • bacterial (often eosinophilia at the initial stage) or parasitic infections (recent trip to the tropics),
  • blood diseases (blood cancers), cancer metastasized or after radiotherapy,
  • endocrine diseases (Addison’s disease), immune disorders.

Eosinophilia can be inherited, and therefore present in some families. Sometimes it is not possible to explain why a person gets the disease.

What is its frequency?

Eosinophilia is common. In industrialized countries, allergic reactions are the most common cause of the problem, but globally, parasitic infections are probably the main culprit. Some level of eosinophilia occurs with 60% of cancers.

How to recognize it?

Eosinophilia is associated with a whole host of potential symptoms, depending on the cause of the problem. These symptoms are usually due to the underlying condition and are rarely caused by eosinophilia per se.

How is the diagnosis made?

This abnormality is diagnosed from a blood test. Sometimes the condition is caught accidentally during a routine check-up or diagnosed after certain symptoms caused by the underlying disease.

What can your doctor do?

If the number of eosinophils in the blood has increased only slightly and there are no symptoms, it is necessary to carry out a check every 1 to 2 months: the doctor will check the evolution of the number of eosinophils and if you develop any symptoms. But if you have symptoms, he will usually refer you to a specialist.

If the number of eosinophils is much higher than normal, a careful examination is done to find the possible cause. The doctor will ask specific questions, perform a physical examination, and perform a detailed analysis of the blood and stool to try to distinguish mild eosinophilia (eg with allergy) from uncontrolled eosinophilia (eg with some forms of leukemia).

If it does not find a clear cause for the problem, further investigations are indicated. Sometimes it is not possible to make a diagnosis.

Treatment depends on the cause of the problem.

Sources

Foreign clinical practice guide ‘Eosinophilia’ (2000), updated on 01.06.2017 and adapted to the Belgian context on 09.07.2019 – ebpracticenet