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Introduction ⬇

Erythropoietin (EPO) is a glycoprotein hormone that regulates erythropoiesis, which promotes the development of RBCs. The levels of EPO in anemia are primarily determined by the degree of anemia; EPO is inversely related to RBC volume and Hct.

EPO is used to investigate obscure anemias. This test is useful in differentiating primary from secondary polycythemia and in detecting the recurrence of EPO-producing tumors. It is also used as an indicator of need for Ep therapy in patients with renal failure (end-stage renal disease).

Normal Findings ⬆ ⬇

5–36 mIU/mL or 5–36 IU/L

Procedure ⬆ ⬇

  1. Obtain a venous blood serum sample of 5 mL using a red-topped tube or SST. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

  2. Separate serum from cells as soon as possible and place in polypropylene tube (not clear plastic-polystyrene). Freeze.

Clinical Implications ⬆ ⬇

  1. EPO is increased appropriately in:

    1. Anemias with very low Hb (e.g., aplastic anemia, hemolytic anemia); hematologic cancers have very high levels

    2. Patients with any iron-deficiency anemia have moderately high levels

    3. Myelodysplasia, chemotherapy, AIDS

    4. Secondary polycythemia vera caused by tissue hypoxia (e.g., high altitude, COPD)

    5. Pregnancy (very high values)

  2. EPO is increased inappropriately in EPO-producing tumors such as the following:

    1. Kidney cysts, kidney transplant rejection

    2. Renal adenocarcinoma

    3. Pheochromocytomas

    4. Cerebellar hemangioblastomas

    5. Polycystic kidney disease

    6. Occasionally, adrenal, ovarian, testicular, breast, and hepatic carcinoma

  3. EPO is decreased appropriately in:

    1. RA

    2. Multiple myeloma

    3. Cancer

  4. EPO is decreased inappropriately in:

    1. Polycythemia vera (primary)

    2. After bone marrow transplantation (weeks 3 and 4)

    3. AIDS before initiating therapy

    4. Autonomic neuropathy

    5. Kidney disease and adult nephrotic syndrome

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure.

  2. Draw blood at the same time for serial determinations: Circadian rhythm is lowest in the morning and 40% higher in late evening.

  3. Alert patient that fasting is not necessary, but a morning specimen is needed.

  4. Note use of any drugs.

  5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Have the patient resume normal activities and medications.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. Monitor for anemia.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care. see Appendix C for more information on vitamin testing.

Interfering Factors ⬆

  1. EPO is increased in:

    1. Pregnancy

    2. Use of anabolic steroids

    3. Administration of thyroid-stimulating hormone, ACTH, epinephrine

    4. Growth hormone (see Appendix E)

  2. EPO is decreased in:

    1. Transfusions

    2. Use of some prescribed drugs (see Appendix E)

    3. Drugs that increase kidney blood flow (e.g., enalapril)

    4. High plasma viscosity