Erythropoietin Test

The erythropoietin test, also known as the serum erythropoietin test or EPO level test, is a test that measures the amount of erythropoietin (EPO) in the blood. EPO is a hormone mostly made by the kidneys. It helps bone marrow to make red blood cells, which carry oxygen from the lungs to the rest of the body.

Doctors use this test to identify the cause of diseases associated with abnormal red blood cell production, such as anaemia (a low red blood cell count) and polycythaemia (a high red blood cell count).

The test also helps to check whether the kidneys are making the correct amount of EPO. Abnormal EPO levels may be associated with kidney problems or bone marrow conditions.

Your doctor may recommend an erythropoietin test if you have symptoms or test results that suggest a problem with red blood cell production.

Symptoms of anaemia (low blood cell count):

• Pale skin
• Feeling tired or weak
• Shortness of breath
• Dizziness
• Headaches

Symptoms of polycythaemia (high red blood cell count):

• Headaches
• Blurred vision
• Flushed face
• Dizziness
• Itchy skin

People who may need this test include:

• Those with anaemia.
• Those with abnormal haemoglobin or haematocrit (percentage of blood that is made up of red blood cells) levels detected during a complete blood count (CBC).
• Those with chronic kidney disease, where reduced EPO production may contribute to anaemia.
• Individuals being evaluated for disorders that affect red blood cell production, including bone marrow problems.
• If further evaluation is required after a routine blood test.

The erythropoietin test is not a routine screening test. Your doctor may recommend the test in the following situations:

The test may help detect or support the diagnosis of the following conditions:

• Iron-deficiency anaemia: This is the most common type of anaemia and occurs when the body does not have enough iron to produce healthy red blood cells. EPO levels may increase as the body tries to produce more red blood cells.
• Haemolytic anaemia: This condition occurs when red blood cells are destroyed faster than they can be replaced. EPO levels often rise to compensate for the increased red blood cell loss.
• Anaemia due to bone marrow suppression: Bone marrow suppression reduces the body's ability to produce blood cells. Measuring EPO levels may help assess the body's response to anaemia.
• Chronic kidney disease (CKD): Healthy kidneys produce most of the body's EPO. Damage to the kidneys may lead to reduced production of EPO, which can result in anaemia.
• Haematological malignancies: Certain blood cancers may be associated with abnormal EPO levels. Measuring these levels in the blood may help identify the cause of unexplained anaemia.

What to Expect Before the Erythropoietin Test

No fasting is required for a standalone Erythropoietin test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise erythropoietin levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Erythropoietin Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes

The erythropoietin test measures the concentration of EPO in the blood.

The normal range of erythropoietin (EPO) is shown in the table below:

Note: The range may vary slightly depending on the laboratory and the testing method used.

The table below explains what the erythropoietin test results may indicate:

The erythropoietin test is generally safe. However, as with any blood test, there are some minor risks.

• Excessive bleeding at the site where the blood sample is collected.
• Feeling faint or light-headed during or after drawing the blood.
• Haematoma, where blood collects under the skin, causing bruising or swelling.
• Infection at the puncture site (rare).

Understanding the Erythropoietin Test Limitations:

• The EPO test cannot identify the exact cause of abnormal red blood cell production. Further tests, like checking iron levels, kidney function, bone marrow, or genes, may be needed to confirm the diagnosis.
• EPO levels may increase during pregnancy. This should be considered when interpreting the test results.
• Recent blood transfusions may temporarily affect EPO levels, making test results more difficult to interpret accurately.

Depending on the results of the erythropoietin test, your doctor may recommend additional tests to identify the underlying cause of abnormal EPO levels or red blood cell production.

• Complete blood count (CBC): Measures the number of red blood cells, white blood cells, and platelets, as well as haemoglobin and haematocrit levels.
• Kidney function tests: Tests such as serum creatinine and estimated glomerular filtration rate (eGFR) help evaluate kidney function because the kidneys produce most of the body's EPO.