Copeptin and acute renal failure in critically ill patients

Introduction

Acute renal failure (ARF) is a common problem in critically ill patients and associated with an adverse prognosis [1]. Vasopressin is a peptide hormone that is released in response to osmotic and haemodynamic changes. An elevation of vasopressin has been suggested to decrease the glomerular filtration rate [2]. In the present study we aimed to assess whether an elevation of vasopressin is associated with the development of ARF in critically ill patients. As vasopressin is highly unstable, copeptin – a stable fragment of the precursor molecule pre-pro-vasopressin that is secreted in equimolar quantities [3] – is used for analysis.

Methods

Three hundred and fifty-two consecutive patients (228 males, age 64 ± 15 years, SAPS 2 52 ± 23) admitted to the ICU of the Department of Cardiology/Medical University of Vienna were included. In addition to routine laboratory assessment, blood samples for determination of copeptin were obtained in all patients on admission. Copeptin was determined by use of the chemiluminescence/coated tube format [3].

Results

Two hundred and seventy-seven patients survived to ICU discharge and 75 patients died. There was a significant inverse correlation between copeptin and glomerular filtration rate (-0.266; P < 0.0001). Patients who developed ARF (n = 114) had higher copeptin plasma levels (180 ± 167 pmol/l vs 95 ± 107 pmol/l; P < 0.0001), a lower mean blood pressure (48 ± 28 mmHg vs 60 ± 24 mmHg; P < 0.0001), were more often in need of vasopressor support (81% vs 63%; P < 0.001) and were more often in shock (72% vs 20%; P < 0.0001) than patients with preserved renal function. Entering all these variables in a stepwise logistic regression model, only shock (P < 0.0001) and copeptin (P < 0.005) were independent predictors for development of ARF.

Conclusion

In critically ill patients, an elevation of plasma copeptin is strongly associated with development of ARF. The therapeutic impact of this observation is still to be elucidated.