Copeptin Responses to Isotonic and Hypertonic Saline Infusion in Healthy Adults

Abstract

Copeptin, a c‐terminal segment of arginine vasopressin (AVP) prohormone, has equimolar secretion to AVP in response to osmotic, stress‐related, and hemodynamic stimulation. For this reason, and because of the difficulties in measuring AVP directly linked to its short half‐life, copeptin has been used as a stable and sensitive surrogate marker for AVP for various clinical indications. However, the plasma copeptin response to osmotic stimulation remains poorly documented.PURPOSEExamine the plasma copeptin response to plasma hyperosmolality induced by hypertonic saline infusion.METHODSSixty healthy adults (50% male, age: 30±1 y, weight: 78.2±15.2 kg, body mass index: 26.9±4.0 kg·m−2) were infused intravenously with 3% (HYPER) or 0.9% (ISO) NaCl for 2 h (0.1 ml·kg−1·min−1) in a counterbalanced, cross‐over design. Blood samples were collected every 30 minutes. Plasma osmolality (POsm), copeptin (PCop; BRAHAMS copeptin proAVP, Thermo Fisher Scientific, Germany), and sodium (PNa) were measured, and changes in plasma volume (PV) were calculated from hematocrit and hemoglobin using the Dill & Costill equation.RESULTSFollowing the HYPER trial, PNa increased from 136±2 mmol ·L−1 to 146.5±3 mmol ·l−1 (P < 0.001), with PV expansion of 18.7±7.3% (P < 0.001). Both POsm and PCop increased significantly (0 min: 286±3 mmol·kg−1 and 4.5±3.7 pmol·L−1; 120 min: 305±4 mmol·kg−1 and 20.4±12.8 pmol·L−1, respectively, P < 0.001). Mean (95% CI) PCop increased with increasing POsm: 3.2 (2.5–3.8) pmol·L−1 for POsm ≤ 284.9 mmol·kg−1; 5.4 (3.8–7.0) pmol·L−1 for POsm 285–289.9; 6.2 (4.3–8.0) pmol·L−1 for POsm 290–294.9; 8.5 (7.1–9.9) pmol·L−1 for POsm 295–299.9; 12.3 (10.2–14.4) pmol·L−1 for POsm 300–304.9; and 19.2 (16.3–22.2) pmol·L−1 for POsm ≥ 305 mmol·kg−1. In contrast, during the ISO trial PNa remained unchanged during the 2‐h infusion (135.9±1.9 vs. 137.6±1.6 mmol·L−1), while PV expanded by 10.5±4.4% (P < 0.001 compared to baseline; P < 0.001 compared to HYPER). Neither POsm (0 min: 285±4,120 min: 287±3 mmol·kg−1) nor PCop (0 min: 4.1±1.8, 120 min: 3.8±3.0 pmol·L−1) were affected during the ISO trial.CONCLUSIONPlasma copeptin was stimulated by increased plasma osmolality during a hypertonic infusion.Support or Funding InformationThis research was supported by Danone ResearchThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.