Erythropoietin (EPO)

Background

Erythropoietin is a glycoprotein (about 30, 400 Daltons) that is produced primarily by the kidney and maintains red blood cell turnover. Renal production of EPO is regulated by changes in oxygen availability. Under conditions of hypoxia, the level of EPO in the circulation increases and this leads to increased production of red blood cells.

The over-expression of EPO may be associated with certain pathophysiological conditions. Polycythemia exists when there is an over-production of red blood cells. Primary polycythemia or polycytemia vera, are caused by EPO-independent growth of red cell progenitors from abnormal bone marrow stem cells and in most cases decreased levels of EPO are found in the serum of affected individuals.

Conversely, various types of secondary polcytemias are associated with the production of elevated levels of EPO. The over-production of EPO may be an adaptive response associated with conditions that produce tissue hypoxia, such as living at high altitude, chronic obstructive pulmonary disease, cyanotic heart disease, sleep apnea, high oxygen affinity haemoglobinopathy, smoking or localised renal hypoxia.

Cases of increased EPO production and erythrocytosis have been reported for patients with renal carcinoma, polycystic kidney disease, Wilm’s disease, hepatoma, liver carcinoma, cerebella hemangioblastomas, adrenal gland tumours and leimyomas.

Deficient EPO production is found in conjunction with certain forms of anaemia. These include anaemia of renal failure, end-stage renal disease, anaemia of prematurity, anaemia of hypothyroidism, and anaemia of malnutrition. Many of these conditions are associated with the generation of IL-1 and TNF-α, factors that have been shown to be inhibitors of EPO activity.

Recombinant human EPO (rh EPO) is used as treatment to stimulate red cell production mainly in chronic renal failure and anaemia caused by chemotherapy, and also the AIDS drug zidovudine.

Reference ranges

Serum: 2.5 – 18.5 IU/L

Specimen requirements

Sample type:

Serum EPO is diurnal in nature, therefore it is important to collect samples at a consistent time of the day.
Morning samples taken between 07:30 and 12.00 noon have been recommended.

Sample identification:

Three patient identifiers from
- Name
- D.O.B.
- Address
- N.H.S. number
- Unit Number
should match on the specimen and request form. This check may be performed prior to centrifugation by the Central Sort department.