Darbepoetin Alfa Increases Plasma N-acetyl-seryl-aspartyl-lysyl-proline Level in Kidney Transplant Recipient: A Case Report

We report a case of elevated plasma N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP)-like immunoreactive substance (IS) level after multiple doses of a recombinant human erythropoietin (rHuEPO), darbepoetin alfa, in a 50 year-old Japanese female who underwent kidney transplantation. Plasma AcSDKP-IS levels showed a gradual decline after kidney transplantation. However, plasma AcSDKP-IS level showed a rapid rise on day 70, and remained at high levels for a period of time and then declined sharply on day 119. After maintaining relatively constant levels from day 119, plasma AcSDKP level showed a rapid rise again on day 168, and declined again on day 238. The two abrupt increases and subsequent sharp decreases of plasma AcSDKP-IS levels correlated temporally with the initiation and discontinuation of the two course of darbepoetin alfa. Although further detailed studies are necessary, administration of darbepoetin alfa may cause a marked increase in plasma AcSDKP level.