Background: Arginine vasopressin (AVP) is a key regulator of water balance, but its instability makes reliable measurement difficult and precludes routine use. We present a method for quantifying AVP release by use of copeptin, a glycopeptide comprising the C-terminal part of the AVP prohormone. Methods: We measured copeptin in 50-L serum and plasma samples from healthy individuals and from critically ill patients with sepsis. Our sandwich immunoluminometric assay used 2 polyclonal antibodies to amino acids 132-164 of pre-provasopressin. Results: The assay yielded results within 3 h. The analytical detection limit was 1.7 pmol/L, and the interlaboratory CV was <20% for values >2.25 pmol/L. The assay was linear on dilution of the analyte. Ex vivo copeptin stability (<20% loss of analyte) for at least 7 days at room temperature and 14 days at 4°C was shown for serum and EDTA-, heparin-, and citrate plasma. Copeptin (median, 4.2 pmol/L; range, 1-13.8 pmol/L) was detectable in 97.5% of 359 healthy individuals and was not associated with age. Median concentrations were considerably higher in men than women, increased significantly after exercise, and were influenced by fasting and water load. Copeptin was significantly (P <0.001) increased in 60 critically ill patients with sepsis (median, 79.5 pmol/L; range, 10.6 -228.0 pmol/L). The correlation between copeptin and AVP for 110 samples was r ‫؍‬ 0.78 (P <0.0001). Conclusions: Copeptin is stable for days after blood withdrawal and can be quickly and easily measured.

The additional use of copeptin seems to allow a rapid and reliable rule out of AMI already at presentation and may thereby obviate the need for prolonged monitoring and serial blood sampling in the majority of patients. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE]; NCT00470587).

Blood pressure is a heritable trait, but no common genetic variants contributing to blood pressure in humans have been definitively established. Natriuretic peptides (NP) have blood pressure-lowering properties. Genotyping SNPs at the NPPA/NPPB locus in 14,743 individuals of European ancestry identified associations of plasma atrial natriuretic peptide with rs5068 (P=8×10−70), rs198358 (P=8×10−30), and rs632793 (P=2×10−10), and of plasma B-type natriuretic peptide with rs5068 (P=3×10−12), rs198358 (P=1×10−25), and rs632793 (P=2×10−68). In 29,717 individuals, the alleles of rs5068 and rs198358 related to increased circulating NP concentrations were associated with lower systolic (P=2×10−6 and 6×10−5, respectively) and diastolic blood pressure (P=1×10−6 and 5×10−5), and reduced odds of hypertension (odds ratio 0.85, 95% confidence interval, 0.79–0.92, P=4×10−5; odds ratio 0.90, 95% confidence interval, 0.85–0.95, P=2×10−4, respectively). Common genetic variants related to circulating NP concentrations contribute to inter-individual variation in blood pressure and hypertension.

Background: 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. Methods: 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 MRproADM concentrations were found in 95 patients with sepsis and 54 patients with cardiovascular disease. Results: 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°C, and 1 year at ؊20°C. MR-proADM values followed a gaussian distribution in healthy individuals with a mean (

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