Plasma levels of mature form of adrenomedullin in patients with haemodialysis.

BACKGROUND Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide with hypotensive effects. Immunoreactive AM in human plasma consists of the biologically active mature form, AM (1-52)-CONH2 (mAM) and the intermediate form, AM-gly-COOH (iAM). However, the different effects of mAM and iAM in patients on haemodialysis (HD) have remained unclear. METHODS Thirty-nine patients on HD and 10 controls were included in this study. We determined plasma levels of mAM and iAM using an immunoradiometric assay that recognizes total AM (tAM) and another that is specific for only mAM. RESULTS The plasma concentrations of mAM and iAM in patients before HD were significantly higher than those in the controls (n=10) (4.76+/-0.28 vs 1.28+/-0.22 fmol/ml, P<0.001, 25.99+/-1.47 vs 8.52+/- 0.91 fmol/ml, P<0.001 respectively). The plasma levels of mAM and iAM before HD significantly and negatively correlated with systolic blood pressure (SBP) (r=-0.46, P<0.01, and r=-0.32, P<0.05 respectively) and diastolic blood pressure (DBP) (r=-0.32, P<0.05, and r=-0.35, P<0.05 respectively). After HD, plasma mAM and iAM levels as well as SBP and DBP were significantly lower than before HD. Plasma levels of mAM and iAM correlated significantly (r=0.73, P<0.001). CONCLUSIONS These data suggest that mAM and/or iAM are involved in blood pressure regulation in patients undergoing HD, and further work is needed to understand the precise role of adrenomedullin in this regulation.