Erythropoietin

Clinical Use
1 Differential diagnosis of anaemia.
2 Differentiation between primary and secondary polycythaemia.
3 Monitoring erythropoietin therapy.

Applications
1 Differential diagnosis of anaemia.
Most anaemic patients have appropriately elevated serum erythropoietin which is dependent on the degree and type of anaemia. Aplastic anaemia, haemolytic anaemia, and anaemia due to iron deficiency result in increased levels of erythropoietin. The erythropoietin concentration in patients with anaemia associated with chronic renal failure is usually inappropriately low due to reduced erythropoietin production in the kidney.

2 Differentiation between primary and secondary polycythaemia.
Patients with polycythaemia rubra vera (primary polycythaemia) typically present with normal or below normal serum erythropoietin whereas those with secondary polycythaemia brought on by hypoxia, as in congestive heart failure or chronic obstructive pulmonary disease, present with elevated erythropoietin levels.

3 Monitoring erythropoietin therapy.
Treatment with recombinant erythropoietin has been shown to be successful in disease states such as anaemia of renal failure, multiple myeloma and AIDS. Monitoring serum erythropoietin reduces toxicity and ensures adequate therapeutic concentrations are achieved.

Patient Preparation
None. Take blood (5 mL).
It is recommended that blood is taken 48h post dose in patients receiving recombinant erythropoietin therapy.

Sample Preparation
Transfer the blood to a sterile glass tube to yield 1 mL of serum. Separate the serum promptly and store at 4C. The sample is stable for 7 days at 4C. Send sample to the SAS laboratory. State all relevant clinical information including whether the patient is receiving recombinant erythropoietin treatment and current haemoglobin level.

Reference Range
Adults: 5.0 – 25.0 mU/mL

Centre offering this assay
King’s College Hospital Erythopoietin and Steroids Service

References
Marsden JT, Sherwood RA, Hillis A and Peters TJ. Monitoring erythropoietin therapy for anaemia of chronic renal failure by serum erythropoietin assays. Ann Clin Biochem 1993; 30: 205-206.
Winearls CG. Erythropoietin. Proc R Coll Physicians Edinb. 1992; 22: 426-443.

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