Article

Measurement of midregional proadrenomedullin in plasma with an immunoluminometric assay

Research Department, B.R.A.H.M.S AG, Biotechnology Centre Hennigsdorf/Berlin, Germany.
Clinical Chemistry (Impact Factor: 7.91). 10/2005; 51(10):1823-9. DOI: 10.1373/clinchem.2005.051110
Source: PubMed

ABSTRACT

Adrenomedullin (ADM) is a potent vasodilatory peptide, and circulating concentrations have been described for several disease states, including dysfunction of the cardiovascular system and sepsis. Reliable quantification has been hampered by the short half-life, the existence of a binding protein, and physical properties. Here we report the technical evaluation of an assay for midregional pro-ADM (MR-proADM) that does not have these problems.
MR-proADM was measured in a sandwich immunoluminometric assay using 2 polyclonal antibodies to amino acids 45-92 of proADM. The reference interval was defined in EDTA plasma of 264 healthy individuals (117 male, 147 female), and increased MR-proADM concentrations were found in 95 patients with sepsis and 54 patients with cardiovascular disease.
The assay has an analytical detection limit of 0.08 nmol/L, and the interassay CV was <20% for values >0.12 nmol/L. The assay was linear on dilution with undisturbed recovery of the analyte. EDTA-, heparin-, and citrate-plasma samples were stable (<20% loss of analyte) for at least 3 days at room temperature, 14 days at 4 degrees C, and 1 year at -20 degrees C. MR-proADM values followed a gaussian distribution in healthy individuals with a mean (SD) of 0.33 (0.07) nmol/L (range, 0.10-0.64 nmol/L), without significant difference between males or females. The correlation coefficient for MR-proADM vs age was 0.50 (P < 0.001). MR-proADM was significantly (P < 0.001) increased in patients with cardiovascular disease [median (range), 0.56 (0.08-3.9) nmol/L] and patients with sepsis [3.7 (0.72-25.4) nmol/L].
MR-proADM is stable in plasma of healthy individuals and patients. MR-proADM measurements may be useful for evaluating patients with sepsis, systemic inflammation, or heart failure.

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    • "Finally, tubes were washed four times with 1 ml of washing solution, and bound chemiluminescence was measured spectroscopically in a luminometer . According to the literature, the lower detection limit of the assay is 0.08 nmol/l, and the functional assay sensitivity defined as the lowest concentration detectable is less than 0.2 nmol/l with an inter-assay coefficient of variation of 20% (Morgenthaler et al., 2005). "
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    • "Median concentrations of MR-proANP are considered to be b45 pmol/L in healthy individuals and the URL is b 250 pmol/L [4] [5]. A reference value study on healthy blood donors and a population-based cohort revealed a median MR-proADM concentration b 0.45 nmol/L and an URL of ~ 0.52 nmol/L [6] [7]. The information given in the package insert and a published study on blood donors [8] refer to a median CT-proET-1 plasma concentration b 47 pmol/L in healthy individuals and an URL b 75 pmol/L. "
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