Endocrine Abstracts

Objective: The response of the hypothalamo-pituitary-adrenal axis to stress is mediated mainly through corticotrophin-releasing hormone and vasopressin. Accordingly, vasopressin levels are increased in septic shock. However, measurement of vasopressin is difficult because of its instability and short half-life. Copeptin is a more stable peptide derived from the same precursor molecule. This study aims to evaluate copeptin levels and its prognostic value in a prospective observational study of 101 consecutive critically ill patients, as compared to 50 healthy controls.

Methods: Copeptin was measured in the serum of all patients with a newly developed sandwich immunoassay.

Results: On admission, 53 patients had sepsis, severe sepsis or septic shock and 48 had systemic inflammatory response syndrome (SIRS). Copeptin levels correlated with basal cortisol levels (r=0.40, P<0.001). Median (range) copeptin values on admission in pmol/l were in patients with SIRS 27.6 (2.3–297), with sepsis 50.0 (8.5–268), with severe sepsis 73.6 (15.3–317) and in patients with septic shock 171.5 (35.1–504), as compared to 5.0 (1.5–30.3) in healthy controls (p for all comparisons versus controls <0.001). On admission, circulating copeptin levels in patients with sepsis, severe sepsis or septic shock were higher in non-survivors (171.5, 46.5–504.0) as compared to survivors (86.8, 8.5–386.0, P=0.01). In a receiver operating curve (ROC) analysis for the survival of patients with sepsis, the AUC for copeptin was 0.75 (95%CI 0.64–0.82). In comparison, the AUC for CRP was 0.55 (0.44–0.65, P=0.02), for basal cortisol 0.60 (0.49–0.69, P=0.08) and for the APACHE II score (0.71, 0.61–0.80, P=0.78).

Conclusions: Copeptin levels are elevated in sepsis, correlate with stress-induced cortisol levels and might provide a useful new tool for an individual risk assessment of septic patients. The availability of a reliable assay for the measurement of vasopressin could also prove useful for the assessment of fluid status in various diseases.