Reference Range

Erythropoietin testing, in combination with other tests, can be used to differentiate polycythemia vera from secondary polycythemia. It can also help differentiate between appropriate and inappropriate secondary polycythemia.

Normal findings^[1]: 5-35 IU/L

Interpretation

Elevated erythropoietin levels are associated with the following:

Iron-deficiency anemia
Anemia due to thalassemia^[2]
Hemolytic anemia
Anemia due to bone marrow suppression
Secondary polycythemia (appropriate [eg, high-altitude, lung disease] or associated with erythropoietin-secreting tumors)
Pregnancy
Testosterone therapy

Suppressed erythropoietin levels are associated with the following:

Anemia due to chronic kidney disease or other chronic diseases (eg, rheumatoid arthritis, HIV infection)^{[3, 4]}
Polycythemia vera
After transfusion
Estrogen therapy

Collection and Panels

Specimen type: Serum

Patient instruction: No need for fasting

Collection tube: Red-top tube or gel-barrier tube

Unacceptable conditions: Grossly hemolyzed specimens

Specimen preparation: Separate serum from cells and transfer to transport tube

Storage/transport temperature: Refrigerated

Stability: Refrigerated, 7 days; frozen, 2 weeks

Panels: None

Description

Erythropoietin is produced by the liver during fetal life. After birth, the kidneys constitute the major source of production. Erythropoietin, a member of class 1 cytokines, is a 30.4-kDa glycoprotein composed of 4 chains of carbohydrate and a protein chain composed of 193 amino acids that undergo a cleavage process, resulting in the production of mature erythropoietin (165 amino acids).

Erythropoietin is secreted by fibroblasts in the renal cortex. These cells possess specific regulatory mechanisms, called hypoxia-inducible factors (HIFs), which, under hypoxic conditions, stimulate the production of erythropoietin, which stimulates the production of erythrocytes.

Indications/Applications

In some conditions, erythropoietin testing can be used in the assessment and differentiation of anemia, especially in patients receiving erythropoietin replacement therapy with an inadequate response.