The three isoforms of Hepcidin measured in human serum by liquid chromatographytandem mass spectrometry

Abstract

H the iron regulatory hormone, is known to have three isoforms (-20, -22, -25 amino acids). Research into hepcidin-25 has been extensive whereas the other isoforms have not received much attention. Because hepcidin dysregulation is evident in iron overload disorders, quantifying this peptide will prove vital in understanding its role in the development of such diseases. However, hepcidin assay methods still remain widely unavailable. Reports on the measurement of this peptide suggest that whereas hepcidin-25 and hepcidin-20 can be found in serum and urine, hepcidin -22 is only found in urine and not in serum. We sought to measure the three hepcidin isoforms in human serum using a method we previously established, based on LC-tandem/ MS and to elucidate their characteristics. Using our LC-tandem/MS method, we identified the hepcidin isoforms in sera from 40 randomly selected healthy volunteers. All three hepcidin isoforms were detected in human sera. Hepcidin-25 levels were highest; however, hepcidin isoform concentrations varied among the individual samples. All three hepcidin isoforms correlated positively with serum ferritin, consistent with the role of hepcidin in iron metabolism. Also, all three isoforms correlated positively with each other. Hepcidin-20 showed a relatively positive correlation with serum creatinine. We found high concentrations of hepcidin-20 in the sera of chronic renal dysfunction patients. In conclusion, we found all three hepcidin isoforms in human sera. Although further studies on the other hepcidin isoforms are required, a simultaneous quantification of all the hepcidin isoforms may provide researchers with novel information and also serve as novel biomarkers.