Erythropoietin, often abbreviated to EPO, is a hormone that is primarily produced by the kidneys. Its main function is to stimulate the production of red blood cells in the bone marrow, which transport oxygen to the body's tissues. This process is essential for maintaining healthy oxygen levels and ensuring the proper functioning of vital organs.

When the body detects a lack of oxygen, such as at high altitudes or in cases of anemia, the kidneys produce more EPO to increase red blood cell production and restore oxygen balance.

Erythropoietin is also a key biomarker used to diagnose and monitor various health conditions. Measuring EPO levels can help identify the cause of anemia, assess kidney function, and detect other disorders that affect red blood cell production.

An EPO test is generally recommended when the doctor suspects an imbalance in red blood cell production, which may be due to a variety of conditions. Here are the most common scenarios:

• To differentiate the types of anemia: Especially when initial blood tests suggest anemia, an EPO test can identify the underlying cause.
• To assess kidney function: Chronic kidney disease can affect erythropoietin production, leading to anemia.
• To monitor bone marrow function: If bone marrow disorders are suspected, such as marrow diseases or cancers.
• To assess the effects of chemotherapy: EPO levels can be tested in patients undergoing cancer treatment to check the impact on red blood cell production.
• In case of unexplained fatigue or weakness: If other symptoms suggest problems transporting oxygen, the EPO test can provide information.

Erythropoietin levels are measured by a blood test. A blood test is taken, usually from a vein in the arm, and analyzed in the laboratory using specialized techniques such as immunochemiluminescence assay.

This test is often done in addition to other blood tests such as:

• Complete blood count (CBC): To assess the total number of red blood cells and other blood components.
• Reticulocyte count: To measure immature red blood cells and assess bone marrow activity.
• Kidney function tests: To check for possible kidney problems that could affect the production of EPO.

Specific preparations before the test:

• Fast for at least 8 hours to ensure accurate results.
• Stopping some medications: After consultation with a doctor, some treatments may be stopped 24 hours before the test.

In adults, normal erythropoietin levels are generally between 2.6 and 18.5 mLu/ml.

Note: Normal measurement units and ranges may vary depending on the laboratory and the specific methods used.

High erythropoietin levels

High levels of EPO may indicate overproduction of red blood cells or compensation for insufficient oxygen levels. Common causes:

• Kidney cysts or adenocarcinoma: Kidney tumors can cause increased erythropoietin production.
• Cerebellar tumors: Some brain tumors stimulate excessive production of EPO.
• Polycystic kidney disease: This genetic condition leads to the formation of kidney cysts that can stimulate EPO.
• Iron Deficiency Anemia: The body produces more EPO to make up for the lack of oxygen transport caused by iron deficiency.
• Hemolytic anemia: The rapid destruction of red blood cells leads to an increase in EPO levels.
• Pregnancy: Increased oxygen demand during pregnancy can lead to higher levels of EPO.

Recommendations for managing high levels:

• Consult a doctor to identify and treat the underlying cause, especially if there are kidney tumors or disorders.
• Watch your iron intake to avoid iron deficiency anemia.
• Maintain adequate hydration to promote kidney function.
• Take regular tests to monitor red blood cell counts and kidney function.

Low erythropoietin levels

Low levels of EPO often signal problems in red blood cell production, leading to insufficient oxygenation in the body. Common causes:

• Chronic kidney disease: Damaged kidneys produce less erythropoietin, leading to anemia.
• Primary polycythemia: This rare condition causes an overproduction of red blood cells, suppressing the production of EPO.
• Rheumatoid arthritis: Chronic inflammations caused by this autoimmune condition can reduce EPO levels.
• Multiple myeloma: This cancer affecting plasma cells in the bone marrow can cause a reduction in EPO.

Recommendations for managing low levels:

• Treat underlying kidney conditions with the help of a health professional.
• Eat foods that are rich in iron, such as leafy green vegetables and lean meats.
• Engage in regular physical activity to improve circulation and oxygenation in the body.
• Follow the doctor's advice to do further tests for suspected autoimmune or bone disorders.

Depending on the cause of your abnormal erythropoietin levels, you may need to see:

• General practitioner: For global management and additional tests.
• Hematologist: In case of blood disorders such as anemia or polycythemia.
• Nephrologist: If kidney disease or dysfunction affects EPO production.
• Oncologist: In case of tumors or cancers affecting the production of erythropoietin.

Regular follow-ups and tailored advice from your medical team are essential to manage any condition related to erythropoietin levels.