What is Eos in Blood Test?

An EOS in blood test is a protein that occurs naturally in the blood. Eos is made of two different proteins called haemoglobin and myoglobin and can be seen under a microscope if there has been inflammation or damage to a muscle. Eos refers to ‘the ocean’ in Greek, for this reason eosinophils are often referred as ‘sea-people’.

White cells, called eosinophils, bear many protrusions on their surface, usually derived from cytoplasmic projections (filopodia), which are membrane-sealed and prevent the cell from penetrating membranes. They can move over a surface using the filopodia to crawl. If a parasite enters the body, eosinophils will be attracted to its particular smell or antigens. They are phagocytic and can ingest foreign particles or microorganisms via a process called phagocytosis. Their protrusions can then break down the ingested material and it converts them into toxic compounds. Toxic compounds are then released to kill the parasite.

Eosinophils circulate in the blood and can be found in tissues throughout the body; they are found more often near sites of parasites and inflammation. They have a higher number of granular bodies than other white cells and can also produce eosinophilic cytoplasmic inclusions.

What do eos do?

Eosinophils are part of the innate immune system. And when they encounter an infection, they release many different types of degranulating molecules (cytokines) that can activate macrophages. These cytokines cause additional inflammatory cells to be attracted to the site of infection (the same way as parasites excite eosinophils). They play a major role in allergic reactions and parasitic infections; however, the level at which they are needed is not well understood.

Note: This picture may not be related to eos in blood test

Eosinophils in blood tests are often elevated when doing a blood test for parasites or inflammation. But the normal range is not established. While in some cases the cause of the increase is clear, an eosinophil can be found in other situations, such as joint and bone pain. More commonly it is used to evaluate one’s health. Many medical conditions have been related to an elevation of eosinophils in blood which include parasitic infection, rheumatoid arthritis, Crohn’s disease and inflammatory bowel disease (such as ulcerative colitis). They are also found with autoimmune disorders such as Graves’ disease and several types of celiac disease. The increase in eosinophils is not always accompanied by an increase in inflammatory markers.

Eosinophilic disorders and places where it is found

Eosinophilic disorders are caused by the over-production of eosinophils, where they can be used to help with allergic responses or in parasitic infections. Eosinophil counts (as well as neutrophil and basophil) have been found to predict disease risk for several autoimmune disorders including rheumatoid arthritis and Crohn’s disease, where a higher count will indicate increased risk of these diseases. Eosinophils have also been found to be associated with ulcerative colitis, Kawasaki disease, and heart disease.

EOS are mostly found in the intestines to help fight parasites and allergic reactions. Along with the eosinophils also come basophils, neutrophils, lymphocytes, monocytes and mast cells. An eosinophil is a type of white blood cell produced in the bone marrow by immature myeloid cells. The presence of granules within the eosinophil makes eosinophilia distinct from other granulocytopenias that can be mistaken for other diseases such as leukemia or other blood diseases.

Eosinophilia is most commonly seen in those with parasitic infections, primarily those involving worms such as schistosomes. They are also found in the blood of people who have had a severe allergic reaction known as anaphylaxis.

Eosinophilia is also associated with inflammatory diseases such as rheumatoid arthritis, Crohn’s disease and ulcerative colitis. Ulcerative colitis is also often called eosinophilic inflammation.

Some Facts about eos in blood test

  • Eosinophils are part of the innate immune system.
  • Eosinophil counts (as well as neutrophils, basophils and mast cells) have been found to predict disease risk for several autoimmune disorders.
  • Eosinophilia is also associated with inflammatory diseases such as rheumatoid arthritis, Crohn’s disease and ulcerative colitis. Ulcerative colitis is also often called eosinophilic inflammation
  • Eos are mostly found in the intestines to help fight parasites and allergic reactions. Along with the eosinophils also come basophils, neutrophils, lymphocytes, monocytes and mast cells.
  • Eosinophils in blood tests are often elevated when doing a blood test for parasites or inflammation. But the normal range is not established.
  • Eosinophilia is most commonly seen in those with parasitic infections, primarily those involving worms such as schistosomes. They are also found in the blood of people who have had a severe allergic reaction known as anaphylaxis.
  • They can be found in cases of joint and bone pain.

Also Read: How can I lower my blood pressure?

Why EOS is done?


An eosinophil count in your blood can help your doctor diagnose underlying conditions such as allergic asthma, parasitic infection, or inflammatory bowel disease.

Please note that this article should not be taken as a medical advice.

Leave a Comment

Your email address will not be published.