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Mid-regional pro-adrenomedullin (MR-proADM) is suggested to be a prognostic indicator for various diseases. Plasma MR-proADM concentration is commonly measured using immunoassays based on its immunochemical characteristics. However, some immunological interactions affect the measured concentration. We developed and validated a sensitive and selective method for measuring plasma MR-proADM concentration using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) and evaluated its clinical applicability. Plasma samples were prepared by protein precipitation and solid-phase extraction. Samples obtained from healthy volunteers (n = 38), patients with chronic kidney disease (CKD) stages 3 and 4-5 (non-dialysis; n = 20 and 17, respectively), and CKD stage 5D (dialysis; n = 34) were analyzed. Within-batch and batch-to-batch accuracy of the UPLC-MS/MS assay for quality control samples ranged from -0.69 % to 8.05 % and from 1.72 % to 5.76 %, respectively. The lower limit of quantification was 0.4 ng mL -1 . The MR-proADM concentration determined using the UPLC-MS/MS assay correlated strongly with that determined using the immunoassay (Pearson's product-moment correlation coefficient [r] = 0.7875, p < 0.001). Median (range) plasma MR-proADM concentrations of healthy volunteers, patients with CKD stages 3 and 4-5, and patients with CKD stage 5D were 0.67 (0.43-1.27), 1.89 (0.65-6.68), 3.86 (1.60-8.75) and 3.97 (0.66-9.20) ng mL -1 , respectively, and a significant difference among four groups was confirmed. We established a sensitive and selective method for determining plasma MR-proADM concentration using UPLC-MS/MS. Our novel UPLC-MS/MS assay for determining plasma MR-proADM concentration can be used in the clinical setting and may have better selectivity than the immunoassay method., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Recently, increased plasma mid-regional pro-adrenomedullin (MR-proADM) concentrations have been demonstrated in patients with chronic renal failure. In this study, we attempted to identify significant clinical factors associated with MR-proADM concentration in stable kidney transplant recipients., Methods: Forty-seven Japanese kidney transplant recipients who underwent transplantation >180days prior to the study were analyzed. To facilitate comparability of anti-hypertensive regimens across recipients taking different drugs, we calculated the treatment intensity score of anti-hypertensive drugs in each recipient. Morning blood samples were collected and plasma MR-proADM concentrations were measured using an enzyme immunoassay., Results: Multiple regression analysis identified treatment intensity score for anti-hypertensive drugs, serum albumin, creatinine clearance and use of lipid-lowering agents as significant independent factors associated with plasma MR-proADM concentration. Adjusted coefficient of determination for this model was 0.46., Conclusion: Apart from indicating lowered renal function, plasma MR-proADM concentration may be a useful biomarker for metabolic disorders, especially hypertension and hyperlipidemia, in stable kidney transplant patients., (Copyright © 2015 Elsevier B.V. All rights reserved.)

We investigated the relationship between plasma mid-regional pro-adrenomedullin (MR-proADM)-like immunoreactive substance (IS) level and clinical characteristics associated with renal failure or resistance to antihypertensive therapy in stable kidney transplant recipients. Forty-six Japanese kidney transplant recipients who underwent transplantation more than 90 days prior to the study were included. To evaluate resistance to antihypertensive therapy, we calculated the treatment intensity score of the antihypertensive drugs in each recipient. Morning blood samples were collected and plasma MR-proADM-IS levels were measured using an enzyme immunoassay. A significant correlation was observed between plasma MR-proADM-IS level with creatinine clearance or treatment intensity score. Multiple regression analysis identified plasma MR-proADM level and body mass index as significant independent factors associated with treatment intensity score. Plasma MR-proADM level may be a useful biomarker indicating the degree of resistance to antihypertensive therapy., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Impaired renal function has been suggested to significantly impact plasma midregional proADM (MR-proADM) level. The aim of this study was to assess whether improvement of renal function after living kidney transplantation has an impact on plasma MR-proADM-like immunoreactive substance (IS) level. Eleven patients with end-stage renal disease (ESRD) who were scheduled to undergo the first living kidney allograft transplantation were enrolled. Plasma MR-proADM-IS levels were measured before and 3, 7, 10, 14, 21, 30, 60 and 90 days after kidney transplantation. Plasma MR-proADM-IS level decreased significantly from day 3 after kidney transplantation compared to before kidney transplantation. A significant negative correlation was observed between creatinine clearance and plasma MR-proADM-IS level from before to 90 days after kidney transplantation (rs=-0.70, p<0.0001). These results suggest that recovery of kidney function after kidney transplantation may lead to decrease in plasma MR-proADM level in patients with ESRD, and that plasma MR-proADM level may depend largely on renal function., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Adrenomedullin (ADM) is a 52-amino acid peptide with a variety of physiologic functions such as immunomodulating activity, direct bactericidal activity, maintenance of renal homeostasis, and vasodilatory activity. Midregional proADM (MR-proADM) is derived from a larger 185-amino acid precursor peptide, prepro-adrenomedulin (preproADM), by posttranslational processing. It is suggested to be co-synthesized with ADM in equimolar amounts and has the advantages over ADM in having a longer half-life, no bioactivity, and no binding to protein. Therefore, MR-proADM serves as a surrogate for ADM secretion. In this study, we attempted to develop an enzyme immunoassay (EIA) for quantifying MR-proADM-like immunoreactive substance (IS), which is applicable for monitoring plasma MR-proADM levels. By using β-d-galactosidase-labeled preproADM(83-94) as a marker antigen, anti-rabbit IgG-coated immunoplate as a bound/free separator, and 4-methylumbelliferyl-β-d-galactopyranoside as a fluorogenic substrate, a sensitive and specific EIA was developed for the quantification of MR-proADM-IS in human plasma. The lower limit of quantification was 0.032 pmol/well, and the steep competitive inhibition EIA calibration curve obtained was linear between 0.16 and 10 nmol/L. By using human plasma samples containing 0.2 and 2.0 nmol/L of MR-proADM, the interassay coefficients of variation (reproducibility) were 10.78% and 8.83%, respectively, and intraassay coefficients were 3.91% and 7.81%. Plasma MR-proADM-IS level was significantly higher in patients with chronic renal failure (1.39 ± 0.50 nmol/L) compared with healthy subjects (0.19 ± 0.07 nmol/L). These results suggest that our EIA may be useful to evaluate plasma MR-proADM levels as a biomarker in various clinical settings., (Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.)