EPO levels alone cannot reliably distinguish between primary and secondary polycythemia; EPO levels are within normal limits in some patients with primary polycythemia.
People living at high altitudes may have higher EPO levels than people living at lower altitudes.
This assay cannot distinguish between endogenous and exogenous EPO.
There are no specific assays for measuring recombinant EPO compounds. Drug levels can only be roughly estimated from the cross-reactivity of the compounds in EPO assays.
Because results obtained with one commercial EPO assay may differ significantly from those obtained with any other, it is recommended that any serial testing performed on the same patient over time should be performed with the same commercial EPO test.
Heterophilic antibodies may interfere in this assay. Results markedly at variance with presentation should be questioned. Additional specimen workup to eliminate heterophilic antibody interference will be performed upon request.
Lower EPO levels than expected have been seen with anemias associated with the following conditions: rheumatoid arthritis, acquired immunodeficiency syndrome, cancer, and ulcerative colitis, sickle cell disease, and in premature neonates.
After allogenic bone marrow transplant, impaired erythropoietin response may delay erythropoietin recovery.
Patients with hypergammaglobulinemia associated with multiple myeloma or Waldenstroms’s disease have impaired production of erythropoietin in relation to hemoglobin concentration. This has been linked to increased plasma viscosity.