Erythropoietin (EPO)

Erythropoietin (EPO) is a hormone the kidneys produce in response to hypoxia and anemia. Its job is to stimulate red blood cell production in the bone marrow. Physiological changes in pregnancy dramatically affect reference ranges, yet this marker may be used to identify certain patterns of anemia in pregnancy. 

EPO Testing

An erythropoietin (EPO) blood test measures the amount of erythropoietin in a blood sample.

Erythropoietin is a glycoprotein hormone primarily produced by the kidneys. It stimulates the maturation of red blood cells. The production of EPO is regulated by the amount of oxygen in cells. When oxygen levels are low, hypoxia and EPO production increase, which leads to an increase in RBC production. 

The fibroblasts of the renal cortex are the primary site of EPO production. It is regulated by the transcription of hypoxia-inducible factor (HIF). HIF is degraded when oxygen levels are normal but will accumulate and bind to EPO gene promoter regions, increasing EPO secretion when oxygen levels are low. 

EPO in Pregnancy

During the first trimester, erythropoietin production is slightly increased but slightly blunted in response to maternal hypoxia. 

EPO levels are relatively low in pregnancy when compared to the degree of maternal anemia. Erythropoietin levels steadily rise throughout the remainder of pregnancy. This is triggered by a combination of hemodilution, mild anemia, increased glomerular filtration rate and overall decreased oxygen in the kidneys.

During pregnancy, the placenta also contributes to erythropoietin production in response to lower oxygen levels in the placental cells, and more significantly in fetal hypoxia. 

Severe blood loss may cause a sharp rise in EPO levels during the postpartum weeks.

High EPO in Pregnancy

Erythropoietin levels have been known to increase two to four times normal ranges during maternal anemia, in some cases reaching levels as high as 10,000 mUI/mL in acute hypoxic stress. 

Abnormally elevated EPO levels are seen in gestational diabetes mellitus. 

Elevated EPO levels are seen in preeclampsia, due to increased placental production in response to placental hypoxia. 

Most Common Causes of High EPO in Pregnancy

• Hypoxia
• Sleep Apnea/Snoring
• Asthma
• Iron Deficiency Anemia
• Secondary Polycythemia
• Anemia of Chronic Inflammation
• Hemolytic Anemia
• Abnormal Clotting/Ischemia of the Placenta
• Thalassemia
• Nutritional Deficiencies (Vitamin B6 (Pyridoxine), Copper)
• Zinc Overload
• Internal Bleeding
• Carrying Multiples
• Hyperthyroidism
• Genetics 

Low EPO in Pregnancy

There is limited data on the application of this indice in pregnancy.

Most Common Causes of Low EPO in Pregnancy

• Primary Polycythemia 
• Hypothyroidism
• Low Progesterone
• Nutritional Deficiencies (Vitamin A, Vitamin D)
• Heavy Metal Exposure
• Autoimmune Disease
• Iron Overload/Hemochromatosis
• Genetics

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Medical Disclaimer:
This content is for educational purposes only and is intended for licensed medical professionals. It is based on current research, subject to change, and not intended to diagnose, treat, or prevent any medical condition. This information does not replace consultation with a qualified healthcare provider. Seek professional medical evaluation and treatment from a licensed provider. Use of this information is at your own risk.​

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