Blood Count

Erythropoietin (EPO) – The Hormone That Controls Red Blood Cell Production

Erythropoietin (EPO) is a hormone primarily produced by the kidneys that regulates the formation of red blood cells. When the body detects low oxygen levels, the kidneys increase EPO production to stimulate the bone marrow to make more red blood cells. A blood test for EPO is used to investigate abnormal red blood cell levels -- both in suspected anemia and in elevated values such as polycythemia.

Why Test Erythropoietin (EPO)?

EPO testing helps distinguish between different causes of anemia and polycythemia. It is recommended when hemoglobin is abnormally high (above 170 g/L in men, 160 g/L in women), when polycythemia vera is suspected, or when investigating anemia that may be due to impaired kidney function. The test guides diagnosis and treatment strategy for blood formation disorders.

What Do High Erythropoietin (EPO) Levels Mean?

High EPO levels may indicate the body is responding to low oxygen levels or anemia. Common causes include chronic hypoxia (lung disease, heart failure, high altitude), iron deficiency or B12/folate deficiency anemia, EPO-producing tumors (some kidney or liver cancers), and secondary polycythemia.

What Do Low Erythropoietin (EPO) Levels Mean?

Low EPO levels are often seen when the kidneys are not producing enough EPO despite a need for it. Causes include chronic kidney disease, primary polycythemia (polycythemia vera, where the body makes too many red blood cells independently of EPO), certain bone marrow disorders, and chronic inflammation.

Symptoms to Watch For

  • Fatigue and weakness (if anemic)
  • Shortness of breath
  • Headache and facial redness (if polycythemic)
  • Dizziness
  • Pale skin
  • Poor exercise tolerance

Who Should Get Tested?

  • People with unexplained anemia or elevated hemoglobin
  • Those with suspected polycythemia vera
  • Patients with chronic kidney disease
  • Individuals with chronic lung or heart disease
  • Anyone being evaluated for blood formation disorders

How to Prepare for Your Test

No special preparation is needed. Bring valid ID to your appointment.

Frequently Asked Questions

Where is erythropoietin produced?
About 90% of EPO is produced by specialized cells in the kidneys. The liver produces a smaller amount. Kidney disease significantly reduces EPO production.
Is EPO the same substance used in sports doping?
Yes. Synthetic EPO (recombinant human erythropoietin) is used medically for anemia in kidney failure but has been misused in endurance sports to boost red blood cell production and oxygen-carrying capacity.
Can EPO help distinguish polycythemia vera from other causes?
Yes. In polycythemia vera, EPO levels are typically low because the bone marrow produces red blood cells autonomously. In secondary polycythemia (e.g., from lung disease), EPO is usually elevated.
How does kidney disease affect EPO?
Damaged kidneys produce less EPO, leading to reduced red blood cell production and anemia. This is called anemia of chronic kidney disease and may be treated with synthetic EPO injections.
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Wellth

Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.

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Medical Disclaimer

The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.