Basis: Recombinant erythropoietin carries fewer negative charges (less anionic) than natural erythropoietin. It therefore does not travel as close to the anode as natural erythropoietin.
Samples: serum or urine
Method:
(1) Erythropoietin is separated and electrophoresed.
(2) The mean value of the peak is determined (reported in mAMU, with AMU = albumin mobility unit).
where:
• Albumin has multiple negative charges so moves close to the anode.
• Albumin shows 1 AMU = 1,000 m AMU.
Interpretation:
• A mean value for the erythropoietin > 670 mAMU is seen if there is no recombinant erythropoietin.
• A mean value for erythropoietin < 670 mAMU indicates that recombinant erythropoietin may be present.
Limitations:
• This assumes that the athlete's personal chemist has not found a way to add more negative charges to the recombinant erythropoietin.
• Positive results are seen 1 to 3 days after use in most men given recombinant erythropoietin. Serum testing appears to be more sensitive after 24 hours.
• 1 week after use the erythropoietin peak is back in the normal range.
