Copeptin: clinical use of a new biomarker

Reduction in central venous pressure enhances erythropoietin synthesis: role of volume-regulating hormones

AIMS

Erythropoiesis is a tightly controlled biological event, but its regulation under non-hypoxic conditions, however, remains unresolved. We examined whether acute changes in central venous blood pressure (CVP) elicited by whole-body tilting affect erythropoietin (EPO) concentration according to volume-regulating hormones.

METHODS

Plasma EPO, angiotensin II (ANGII), aldosterone, pro-atrial natriuretic peptide (proANP) and copeptin concentrations were measured at supine rest and up to 3 h during 30° head-up (HUT) and head-down tilt (HDT) in ten healthy male volunteers. Plasma albumin concentration was used to correct for changes in plasma volume and CVP was estimated through the internal jugular vein (IJV) aspect ratio with ultrasonography.

RESULTS

From supine rest, the IJV aspect ratio was decreased and increased throughout HUT and HDT respectively. Plasma EPO concentration increased during HUT (13%; P = 0.001, P for linear component = 0.017), independent of changes in albumin concentration. Moreover, ANGII and copeptin concentrations increased during HUT, while proANP decreased. The increase in EPO concentration during HUT disappeared when adjusted for changes in copeptin. During HDT, EPO, ANGII and copeptin concentrations remained unaffected while proANP increased. In regression analyses, EPO was positively associated with copeptin (β = 0.55; 95% CI = 0.18, 0.93; P = 0.004) irrespective of changes in other hormones and albumin concentration.

CONCLUSION

Reduction in CVP prompts an increase in plasma EPO concentration independent of hemoconcentration and hence suggests CVP per se as an acute regulator of EPO synthesis. This effect may be explained by changes in volume-regulating hormones.

Low-Osmolar Diet and Adjusted Water Intake for Vasopressin Reduction in Autosomal Dominant Polycystic Kidney Disease: A Pilot Randomized Controlled Trial

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) affects millions of people worldwide. Vasopressin promotes disease progression.

STUDY DESIGN

A randomized controlled trial with equal (1:1) allocation.

SETTING & PARTICIPANTS

This trial examined the effect of combining a low-osmolar (low-sodium [1,500mg/d], low-protein [0.8g per kilogram of body weight]) diet and adjusted water intake on vasopressin secretion in 34 patients with ADPKD.

INTERVENTION

Participants were randomly assigned to receive a low-osmolar diet followed by adjusted water intake to achieve urine osmolality ≤ 280mOsm/kg water versus no intervention for 2 weeks.

OUTCOME

The primary outcome of the study was change (delta) in copeptin levels and urine osmolality between the intervention and control groups from baseline to 2 weeks.

MEASUREMENTS

Fasting plasma copeptin level, 24-hour urine osmolality, and total solute intake.

RESULTS

Baseline characteristics of the 2 groups were similar. Mean plasma copeptin levels and urine osmolality declined from 6.2±3.05 (SD) to 5.3±2.5pmol/L (P=0.02) and from 426±193 to 258±117mOsm/kg water (P=0.01), respectively, in the intervention group compared to a nonsignificant change in the control group (from 4.7±3.6 to 5.07±4pmol/L [P=0.2] and 329±159 to 349±139mOsm/kg water [P=0.3], respectively). The change in copeptin levels (primary outcome) and urine osmolality was statistically significant between the intervention and control groups (delta copeptin, -0.86±1.3 vs +0.39±1.2pmol/L [P=0.009]; delta urine osmolality, -167±264 vs +20±80mOsm/kg water [P=0.007], respectively). Total urinary solute decreased in only the intervention group and significantly differed between groups at week 1 (P=0.03), reducing mean water prescription from 3.2 to 2.6L/d.

LIMITATIONS

Small sample size and short follow-up.

CONCLUSIONS

We developed a stepwise dietary intervention that led to a significant reduction in vasopressin secretion in patients with ADPKD. Furthermore, this intervention led to a reduction in water required for vasopressin reduction.

Serum NGAL and copeptin levels as predictors of acute kidney injury in asphyxiated neonates

Background

Acute kidney injury (AKI) is the most common complication of perinatal asphyxia. Recent research indicates that serum neutrophil gelatinase-associated lipocalin (NGAL) is an early marker for AKI, but there are the lacks of data about its use in term neonates with perinatal asphyxia.

Methods

A prospective cohort study was conducted on 43 term neonates. Umbilical cord blood and 24 h after birth serum NGAL, copeptin, creatinine, and molality were measured in all asphyxiated and controls neonates.

Results

During the study period, 8 of asphyxiated nenates (18.6 %) suffered from AKI, while 35 newborns have no signs of AKI and 30 healthy infants. We did not observe any differences in creatinine and copeptin levels, as well as serum osmolality in all three investigated groups (AKI, no-AKI, and controls) in cord blood, and 24 h after birth. Serum NGAL levels in umbilical cord blood were significantly higher in the AKI group (174.3 ng/mL) compared with no-AKI (88.5 ng/mL, p = 0.01) and control groups (28.5 ng/mL, p < 0.001), and 24 h after birth (respectively, AKI 152.5 ng/mL vs no-AKI 74.9 ng/mL, p = 0.02 vs controls 39.1 ng/mL, p < 0.001). NGAL concentration showed a strong negative correlation to umbilical artery pH (Rho = −0.42, p = 0.04), base excess (Rho = −0.31, p = 0.03), and Apgar score in 1st min (Rho = −0.41, p = 0.02) and 5th min of life (Rho = −0.20, p = 0.001). ROC curve analysis demonstrated a good predictive value for NGAL levels (>140.7 ng/mL) which allows to diagnose AKI in asphyxiated patients with 88.9 % sensitivity (95 % CI 75–95 %) and 95.0 % specificity (95 % CI 76–99 %).

Conclusion

NGAL seems to be a promising marker, even in subclinical AKI in neonates, due to its high specificity, but copeptin did not meet expectations.

[Usefulness of copeptin in the diagnosis of acute coronary syndrome in the emergency department of a tertiary hospital]

OBJECTIVES

This study was conducted in order to evaluate the usefulness of copeptin (a stable fragment of the precursor of arginine vasopressin) in the differential diagnosis of acute chest pain of probable coronary origin.

MATERIAL AND METHODS

The study includes 82 patients who were initially evaluated according to the protocol of a patient with suspected acute coronary syndrome (ACS) in our Emergency Department, including the determination of troponin and copeptin with specimens taken on admission (time 0) and at 6h.

RESULTS

Statistically significant differences were observed in copeptin concentrations at time 0 among patients diagnosed with non-ST-segment elevation (NTEACS): 42.1±38.7pmol/L and non-NSTEACS patients: 15.6±21.2pmol/L (P<. 01). However, the differences did not reach statistical significance at 6h (P=.093). The analysis of the area under the ROC curve for Copeptin in NSTEACS patients at time 0 was 0.713, with a confidence interval of 95% from 0.592 to 0.834 and a significance level of P=.001.

CONCLUSIONS

The concentration of copeptin represents an additional value in the differentiation between NSTEACS patients and non-NSTEACS patients, as well as between ACS patients and patients with stable angina. The cut-off point of 10pmol/L provides the best values for sensitivity, negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) in the diagnosis of NSTEACS patients.

Elevated copeptin is a prognostic factor for mortality even in patients with renal dysfunction

BACKGROUND

Copeptin has turned out to give valuable prognostic information for future cardiovascular events. However, since its plasma concentration directly depends on renal function, the value of copeptin as a predictor for outcome also in patients with chronic kidney disease (CKD) is unknown.

METHODS

In this single-center substudy of the German Coronary Artery Disease-REnal Failure (CAD-REF) registry, 301 patients with an angiographically diagnosed stenosis ≥50% in at least one major coronary vessel were included. Estimated glomerular filtration rate (eGFR) was determined using the MDRD formula and patients were classified according to their CKD stage. Copeptin concentrations were measured before initial angiography. Follow-up was performed at 180days, study endpoint was all-cause mortality.

RESULTS

Of the 301 included patients, 35 (11.6%) patients had no CKD, 113 (37.5%) had CKD stage 1 or 2, 117 (38.9%) had CKD stage 3, and 36 (12.0%) had CKD stage 4 or 5. Copeptin was elevated (≥14pmol/L) in 81 (26.9%) patients and normal (<14pmol/L) in 220 (73.1%) patients. Copeptin values significantly increased with decreasing eGFR (p<0.001) and were strongly correlated with creatinine values (r=0.567, p<0.001). During 180days of follow-up, 15 patients (5.0%) died, 10 of them with elevated copeptin values. Multivariate Cox regression analysis showed that copeptin was the sole predictor for mortality (HRR 5.317 (95% CI 1.653-17.098), p=0.005), independent of serum creatinine.

CONCLUSION

Elevated copeptin can be used as a valuable prognostic factor for intermediate-term mortality in patients with both coronary artery and renal disease.

Copeptin, insulin-like growth factor binding protein-1 and sitagliptin: A report from the BEta-cell function in Glucose abnormalities and Acute Myocardial Infarction study

PURPOSE

To investigate whether sitagliptin affects copeptin and osmolality, suggesting arginine vasopressin activation and a potential for fluid retention, compared with placebo, in patients with a recent acute coronary syndrome and newly discovered type 2 diabetes or impaired glucose tolerance. A second aim was to confirm whether copeptin correlated with insulin-like growth factor binding protein-1.

METHODS

Fasting blood samples were used from the BEta-cell function in Glucose abnormalities and Acute Myocardial Infarction trial, in which patients recently hospitalized due to acute coronary syndrome and with newly detected abnormal glucose tolerance were randomized to sitagliptin 100 mg once daily (n = 34) or placebo (n = 37). Copeptin, osmolality and insulin-like growth factor binding protein-1 were analysed at baseline and after 12 weeks.

RESULTS

Copeptin and osmolality were unaffected by sitagliptin. There was no correlation between copeptin and insulin-like growth factor binding protein-1.

CONCLUSION

Sitagliptin therapy does not appear to be related to activation of the arginine vasopressin system.

Maternal serum copeptin concentrations in early- and late-onset pre-eclampsia

OBJECTIVE

Early-onset pre-eclampsia is primarily associated with placental dysfunction, whereas late-onset pre-eclampsia is defined as a maternal constitutional disorder. As a protein cosynthesized with vasopressin, copeptin is a potential marker of metabolic syndrome and insulin resistance, which shares similar risk factors with pre-eclampsia. The aim of this study was to investigate the copeptin levels in patients with early-onset and late-onset pre-eclampsia.

MATERIALS AND METHODS

A total of 80 pregnant women receiving antenatal and obstetric care were recruited. The patients were subdivided into four groups: Early-onset pre-eclampsia (n = 20), late-onset pre-eclampsia (n = 20), and two control groups of similar gestational ages for both pre-eclamptic groups (n = 20 in each group). The maternal serum copeptin levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

The mean copeptin levels were 0.92 ± 0.57 ng/mL and 1.65 ± 0.95 ng/mL in the early-onset and late-onset pre-eclampsia groups, respectively. These values were higher compared with the control groups (0.54 ± 0.25 ng/mL and 1.15 ± 0.94 ng/mL, respectively). However, the difference was only statistically significant in the early-onset pre-eclampsia group (p = 0.011). Copeptin levels were associated only with gestational age and systolic-diastolic blood pressure.

CONCLUSION

Our results suggest that copeptin levels might be useful in the evaluation of the severity of pre-eclampsia. However, copeptin might be involved in early- rather than late-onset pre-eclampsia.

Prognostic assessment in COPD without lung function: the B-AE-D indices

Several composite markers have been proposed for risk assessment in chronic obstructive pulmonary disease (COPD). However, choice of parameters and score complexity restrict clinical applicability. Our aim was to provide and validate a simplified COPD risk index independent of lung function.The PROMISE study (n=530) was used to develop a novel prognostic index. Index performance was assessed regarding 2-year COPD-related mortality and all-cause mortality. External validity was tested in stable and exacerbated COPD patients in the ProCOLD, COCOMICS and COMIC cohorts (total n=2988).Using a mixed clinical and statistical approach, body mass index (B), severe acute exacerbations of COPD frequency (AE), modified Medical Research Council dyspnoea severity (D) and copeptin (C) were identified as the most suitable simplified marker combination. 0, 1 or 2 points were assigned to each parameter and totalled to B-AE-D or B-AE-D-C. It was observed that B-AE-D and B-AE-D-C were at least as good as BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity), ADO (age, dyspnoea, airflow obstruction) and DOSE (dyspnoea, obstruction, smoking, exacerbation) indices for predicting 2-year all-cause mortality (c-statistic: 0.74, 0.77, 0.69, 0.72 and 0.63, respectively; Hosmer-Lemeshow test all p>0.05). Both indices were COPD specific (c-statistic for predicting COPD-related 2-year mortality: 0.87 and 0.89, respectively). External validation of B-AE-D was performed in COCOMICS and COMIC (c-statistic for 1-year all-cause mortality: 0.68 and 0.74; c-statistic for 2-year all-cause mortality: 0.65 and 0.67; Hosmer-Lemeshow test all p>0.05).The B-AE-D index, plus copeptin if available, allows a simple and accurate assessment of COPD-related risk.

American Society of Nephrology Quiz and Questionnaire 2015: Electrolytes and Acid-Base Disorders

The Nephrology Quiz and Questionnaire remains an extremely popular session for attendees of the annual Kidney Week meeting of the American Society of Nephrology. During the 2015 meeting the conference hall was once again overflowing with eager quiz participants. Topics covered by the experts included electrolyte and acid-base disorders, glomerular disease, end-stage renal disease and dialysis, and kidney transplantation. Complex cases representing each of these categories together with single-best-answer questions were prepared and submitted by the panel of experts. Before the meeting, training program directors of nephrology fellowship programs and nephrology fellows in the United States answered the questions through an internet-based questionnaire. During the live session members of the audience tested their knowledge and judgment on the same series of case-oriented questions in a quiz. The audience compared their answers in real time using a cell-phone app containing the answers of the nephrology fellows and training program directors. The results of the online questionnaire were displayed, and then the quiz answers were discussed. As always, the audience, lecturers, and moderators enjoyed this highly educational session. This article recapitulates the session and reproduces selected content of educational value for theClinical Journal of the American Society of Nephrologyreaders. Enjoy the clinical cases and expert discussions.

Copeptin is an independent prognostic factor for transplant-free survival in cirrhosis

BACKGROUND & AIMS

Copeptin is a stable cleavage product of the arginine vasopressin (AVP) precursor and is equimolarly secreted with AVP. Copeptin is currently considered a reliable prognostic marker in a wide variety of diseases other than cirrhosis. We aimed to investigate the association between severity of cirrhosis and copeptin concentrations and to confirm whether copeptin is of prognostic significance in cirrhosis.

METHODS

One hundred and eighty-four cirrhotic patients hospitalized in two tertiary referral centres were studied. Serum copeptin was measured in samples obtained at hospital admission. Differences in serum copeptin between Child-Pugh classes were evaluated using the Kruskal-Wallis test. Cox proportional hazard regression and Kaplan-Meier analyses were performed to evaluate associations of copeptin and other possible prognostic factors with 6- and 12-month mortality.

RESULTS

Median serum copeptin (interquartile range) increased significantly through Child-Pugh classes A [5.4 (3.1-10.7) pmol/L], B [9.6 (6.0-17.3) pmol/L] and C [13.8 (5.8-34.1) pmol/L, P < 0.01]. Patients with serum copeptin >12.3 pmol/L displayed significantly higher mortality rates at 6 and 12 months as compared to those with serum copeptin ≤12.3 pmol/L (Log-rank test: P < 0.01). Serum copeptin >12.3 pmol/L was significantly associated with mortality, particularly at 6 months, independently of age, clinical parameters and Model for End stage Liver Disease (MELD), MELD-sodium and Child-Pugh score.

CONCLUSIONS

Serum copeptin concentration increases significantly along with the severity of cirrhosis as defined by the Child-Pugh classification. A high serum copeptin concentration predicts survival, particularly at 6 months, independently of liver-specific scoring systems in a heterogeneous population of hospitalized cirrhotic patients.

A novel AVP gene mutation in a Turkish family with neurohypophyseal diabetes insipidus

PURPOSE

Familial neurohypophyseal diabetes insipidus (FNDI) is a rare, autosomal dominant, inherited disorder which is characterized by severe polydipsia and polyuria generally presenting in early childhood. In the present study, we aimed to analyze the AVP gene in a Turkish family with FNDI.

METHODS

Four patients with neurohypophyseal diabetes insipidus and ten healthy members of the family were studied. Diabetes insipidus was diagnosed by the water deprivation test in affected family members. Mutation analysis was performed by sequencing the whole coding region of AVP-NPII gene using DNA isolated from peripheral blood samples.

RESULTS

Urine osmolality was low (<300 mOsm/kg) during water deprivation test, and an increase more than 50 % in urine osmolality and recovery of the symptoms were observed by the administration of desmopressin in all patients. Plasma copeptin levels were lower than expected according to plasma osmolality. Pituitary MRI revealed partial empty sella with a bright spot in index patient and a normal neurohypophysis in the other affected subjects. Genetic screening revealed a novel, heterozygous mutation designated as c.-3A>C in all patients.

CONCLUSION

c.-3A>C mutation in 5'UTR of AVP gene in this family might lead to the truncation of signal peptide, aggregation of AVP in the cytoplasm instead of targeting in the endoplasmic reticulum, thereby could disrupt AVP secretion without causing neuronal cytotoxicity, which might explain the presence of bright spot. The predicted effect of this mutation should be investigated by further in vitro molecular studies.

A copeptin-based classification of the osmoregulatory defects in the syndrome of inappropriate antidiuresis

The syndrome of inappropriate antidiuretic hormone secretion (SIADH), also referred to as syndrome of inappropriate antidiuresis (SIAD), is the most common cause of hyponatremia characterized by extracellular hypotonicity and impaired urine dilution in the absence of any recognizable nonosmotic stimuli for the antidiuretic hormone arginine vasopressin (AVP). Hyponatremia in SIADH is primarily the result of excessive water retention caused by a combination of inappropriate antidiuresis and persistent fluid intake in the presence of impaired osmoregulated inhibition of thirst. It is sometimes aggravated by a sodium deficiency caused by a decreased intake or a secondary natriuresis in response to elevated extracellular volume. Inappropriate antidiuresis usually results from endogenous production of AVP that can be either ectopic (from a malignancy) or eutopic (from the hypothalamus/neurohypophysis). Regardless of its origin, different types of osmotic dysregulation of AVP have been reported with possibly fundamental deviations in treatment need and efficacy. A recent quantitative analysis of 50 patients with SIADH, which underwent serial measurements of copeptin during hypertonic saline infusion, revealed five distinct types of osmoregulatory defect ("type A to E") without affiliation to specific underlying diseases. In addition to apparently impaired osmoregulated inhibition of AVP release in the majority of patients, 12% of patients showed an AVP-independent mechanism of inappropriate antidiuresis, whilst 20% of them presented a reverse relation between hormone release and serum osmolality, presumably related to interrupted nonosmotic inhibitory pathways. The interference of these different types of SIAD with clinical presentation and therapy response will be a relevant subject for future research.

Copeptin Levels Do Not Correlate With Cross-Clamping Time in Patients Undergoing Carotid Endarterectomy Under General Anesthesia

Copeptin is a sensitive and more stable surrogate marker for arginine vasopressin. In this study, we evaluated copeptin levels in carotid endarterectomy (CEA) patients, perioperatively, to determine whether copeptin levels can be related to carotid artery cross clamping (CC) time and to postoperative neurological outcomes. Copeptin, interleukin 6, C-reactive protein, cortisol, and brain natriuretic peptide were measured preoperatively (T1) and 3 hours postoperatively (T3) as well as intraoperatively (T2). We recruited 77 patients. Values of copeptin rose gradually over the observed times: T1 = 7.9 (6.4-9.6), T2 = 12.6 (9.3-16.8), and T3 = 72.3 (49.1-111.2) pmol/L. There was a significant difference for repeated measurement ( P = .000, P = .000, and P = .000). Duration of carotid artery CC during CEA does not affect postoperative copeptin level (CC ≤ 13 minutes: 106.8 ± 93.6 pmol/L, CC > 13 minutes: 96.7 ± 89.1 pmol/L; P = .634). Preoperative copeptin level was significantly higher in patients with ulcerated plaque morphology. Activation of the stress axis in patients undergoing CEA results in copeptin elevation. Duration of CC during CEA does not affect postoperative copeptin levels.

Copeptin in Heart Failure

Heart failure (HF) is one of the most common causes of hospitalization and mortality in the modern Western world and an increasing proportion of the population will be affected by HF in the future. Although HF management has improved quality of life and prognosis, mortality remains very high despite therapeutic options. Medical management consists of a neurohormonal blockade of an overly activated neurohormonal axis. No single marker has been able to predict or monitor HF with respect to disease progression, hospitalization, or mortality. New methods for diagnosis, monitoring therapy, and prognosis are warranted. Copeptin, a precursor of pre-provasopressin, is a new biomarker in HF with promising potential. Copeptin has been found to be elevated in both acute and chronic HF and is associated with prognosis. Copeptin, in combination with other biomarkers, could be a useful marker in the monitoring of disease severity and as a predictor of prognosis and survival in HF.

Serum copeptin and pregnancy outcome in preeclampsia

Background:

A number of biochemical predictors of preeclampsia have been reported, but little is known about their possible relationship with maternal and fetal outcomes. This study determined serum copeptin in pregnant women with preeclampsia and assessed its relationship with pregnancy outcomes.

Materials and Methods:

Thirty women with severe preeclampsia (SP), 30 with mild preeclampsia (MP), and 30 with uncomplicated pregnancy were enrolled into this study. Serum copeptin, creatinine, and liver function were determined using enzyme-linked immunosorbent assay and colorimetry as appropriate. Pregnancy outcomes, both maternal and fetal, were taken using standard methods.

Results:

Copeptin was significantly elevated in preeclampsia subjects compared with controls and in SP compared with MP. Assessing the diagnostic property of copeptin for preeclampsia, the area under the curve for copeptin was 0.99. Nine (30%) and 3 (10%) of SP and MP, respectively had abruptio placenta while 6 (20%), 2 (6.7%), and 1 (3.3%) still births were recorded in SP, MP, and controls, respectively. Neonates of mothers with preeclampsia had significantly lower birth weight, infant length, ponderal index, and head circumference compared with neonates of the controls. Copeptin had a significant inverse relationship with birth weight, ponderal index, head circumference, Apgar score, and infant length in neonates of mothers with preeclampsia.

Conclusion:

Serum copeptin level in the third trimester could predict preeclampsia and its elevation is associated with adverse perinatal outcome.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

Association of HPA axis hormones with copeptin after psychological stress differs by sex

INTRODUCTION

Copeptin levels are elevated in severe medical conditions, an effect that is attributed to elevated arginine vasopressin (AVP) levels in response to physiological stress, resulting in activation of hypothalamus-pituitary-adrenal (HPA) axis. In the current study, we wanted to determine if copeptin is responsive to psychological stress, correlates with cortisol and adrenocorticotropin hormone (ACTH), and if associations differed by sex.

MATERIALS AND METHODS

In a cross-sectional study that included 100 healthy men (41%) and women (59%) (aged 18-30 years; mean 24.6 ± 3 years), who underwent the Trier Social Stress Test (TSST), we examined the association between percent change (peak-baseline/baseline) in copeptin levels and percent change in log ACTH and cortisol. Three baselines samples were drawn followed by blood sampling at 20, 35, 50, 65 and 85 min after TSST.

RESULTS

There was a significant positive association between the percent change in copeptin and the percent change in log-transformed salivary cortisol (β-coefficient=0.95; p=0.02). The association between percent change in copeptin and log-transformed serum cortisol was not statistically significant in the overall population. There was a trend for a non-significant association between percent change in copeptin and percent change in log-transformed ACTH (β-coefficient=1.14; p=0.06). In males, there was a significant positive association between the percent change in copeptin levels and log-transformed salivary (β-coefficient=1.33, p=0.016) and serum cortisol (β-coefficient=0.69, p=0.01), whereas in women there was no statistically significant association.

CONCLUSIONS

We found a significant positive association between percent change in copeptin and percent change in salivary and serum cortisol among males only.

Copeptin predicts 10-year all-cause mortality in community patients: a 10-year prospective cohort study

Background:

Copeptin, the C-terminal part of the arginine vasopressin (AVP) precursor peptide, is secreted in response to stress and correlates with adverse clinical outcomes in the acute-care hospital setting. There are no comprehensive data regarding its prognostic value in the community. We evaluated associations of copeptin levels with 10-year mortality in patients visiting their general practitioner (GP) for a respiratory infection included in a previous trial.

Methods:

This is a post hoc analysis including data from 359 patients included in the PARTI trial. Copeptin was measured in batch-analysis on admission and after 7 days. We calculated Cox regression models and area under the receiver operating characteristic curve (AUC) to assess an association of copeptin with mortality and adverse outcome. Follow-up data were collected by GP, patient and relative tracing through phone interviews 10 years after trial inclusion.

Results:

After a median follow-up of 10.0 years, mortality was 9.8%. Median admission copeptin levels (pmol/L) were significantly elevated in non-survivors compared to survivors (13.8, IQR 5.9–27.8; vs. 6.3 IQR 4.1–11.5; p<0.001). Admission copeptin levels were associated with 10-year all-cause mortality [age-adjusted hazard ratio 1.7 (95% CI, 1.2–2.5); p<0.001, AUC 0.68]. Results were similar for discharge copeptin levels. Copeptin also predicted adverse outcomes defined as death, pulmonary embolism and major adverse cardiac and cerebrovascular events.

Conclusions:

In a sample of community-dwelling patients visiting their GP for a respiratory infection, copeptin levels were associated with 10-year all-cause mortality. In conjunction with traditional risk factors, this marker may help to better direct preventive measures in this population.

Arginine Vasopressin and Copeptin in Perinatology

Arginine vasopressin (AVP) plays a major role in the homeostasis of fluid balance, vascular tonus, and the regulation of the endocrine stress response. The measurement of AVP levels is difficult due to its short half-life and laborious method of detection. Copeptin is a more stable peptide derived from the same precursor molecule, is released in an equimolar ratio to AVP, and has a very similar response to osmotic, hemodynamic, and stress-related stimuli. In fact, copeptin has been propagated as surrogate marker to indirectly determine circulating AVP concentrations in various conditions. Here, we present an overview of the current knowledge on AVP and copeptin in perinatology with a particular focus on the baby's transition from placenta to lung breathing. We performed a systematic review of the literature on fetal stress hormone levels, including norepinephrine, cortisol, AVP, and copeptin, in regard to birth stress. Finally, diagnostic and therapeutic options for copeptin measurement and AVP functions are discussed.

Effect of increased water intake on plasma copeptin in patients with chronic kidney disease: results from a pilot randomised controlled trial

OBJECTIVES

Increased water intake may have a beneficial effect on the kidney through suppression of plasma vasopressin. We examined the effect of increased water intake on plasma copeptin (a marker of vasopressin) over 6 weeks in patients with chronic kidney disease.

DESIGN

Secondary analysis of a randomised controlled parallel-group pilot trial.

SETTING

Canada, 2012-2013.

PARTICIPANTS

28 patients with stage 3 chronic kidney disease randomised (2:1) to a hydration (n=17) or control group (n=11).

INTERVENTION

The hydration group was coached to increase water intake by up to 1.5 L/day for 6 weeks. The control group was asked to maintain regular water intake.

MEASURES AND OUTCOMES

Participants provided blood and 24 h urine samples at baseline and 6 weeks. Change in plasma copeptin was compared within and between study groups.

RESULTS

Participants were 64% male with a mean age of 62 years and an estimated glomerular filtration rate of 40 mL/min/1.73 m(2). Between baseline and 6 weeks, 24 h urine volume increased by 0.7 L/day in the hydration group, rising from 2.3 to 3.0 L/day (p=0.01), while decreasing by 0.3 L/day among controls, from 2.0 to 1.7 L/day (p=0.07); between-group difference: 0.9 L/day (95% CI 0.37 to 1.46; p=0.002). In the hydration group, median copeptin decreased by 3.6 pmol/L, from 15.0 to 10.8 pmol/L (p=0.005), while remaining stable among controls at 19 pmol/L (p=0.76; p=0.19 for the between-group difference in median change); the between-group difference in mean change was 5.4 pmol/L (95% CI -1.2 to 12.0; p=0.11).

CONCLUSIONS

Adults with stage 3 chronic kidney disease can be successfully randomised to drink approximately 1 L more per day than controls. This increased water intake caused a significant decrease in plasma copeptin concentration. Our larger 12-month trial will examine whether increased water intake can slow renal decline in patients with chronic kidney disease.

TRIAL REGISTRATION NUMBER

NCT01753466.

High incidence of hyponatremia in rowers during a four-week training camp

PURPOSE

To investigate the incidence of hyponatremia and its relationship to plasma copeptin, a surrogate marker for arginine vasopressin (AVP) during 28 days of high-volume rowing training.

METHODS

Thirty rowers from the German junior national team (21 male) were studied during a training camp. Serum sodium ([Na(+)]), osmolality, and copeptin were measured before the beginning of the camp (day 0), and at days 7, 13, 18, 24, and 28. Daily fluid intake, body weight, urine parameters, and training volume were recorded.

RESULTS

Seventy percent of the rowers developed hyponatremia at least once. At day 18, training volume and incidence of hyponatremia (43%) were highest. [Na(+)] decreased from 143 ± 9 mmol·L(-1) (day 0) to 135 ± 5 mmol·L(-1) (day 18, P < .01). Hyponatremia was correlated significantly with weight gain compared with the previous day (P < .01). Copeptin decreased from day 0 to 28 (male: 6.7 ± 2.8 to 3.6 ± 1.7 pmol·L(-1); P < .05; female: 4.8 ± 1.1 to 3.2 ± 1.5 pmol·L(-1); P < .05), being only partially suppressed. Relative fluid intake per body surface area increased from day 7 (male: 2.79 ± 0.78 L·m(-2); female: 2.20 ± 0.70 L·m(-2)) to day 28 (3.88 ± 0.69 L·m(2) and 2.65 ± 0.93 L·m(-2); P < .05). No athlete developed symptomatic hyponatremia.

CONCLUSION

Prolonged high-volume rowing training can lead to a high incidence of hyponatremia. Overdrinking and inadequate suppression of AVP contribute to its development.

Copeptin: Pathophysiology and potential clinical impact

Copeptin, a C-terminal part of the precursor pre-provasopressin is a novel biomarker of arginine-vasopressin (AVP) system. Measurements of AVP concentration are not used in clinical practice because of technical difficulties. Copeptin is synthesized in stoichiometric ratio with AVP, hence it reflects vasopressin concentration in human plasma and serum. This review outlines current research concerning the role of copeptin as a prognostic marker in different diseases and its potential clinical value.

Copeptin as a biomarker in heart failure

Increased neurohormonal activation is a key feature of heart failure (HF). Copeptin is a surrogate marker for proarginine vasopressin and the prognostic value of copeptin has been reported for multiple disease states of both nonvascular and cardiovascular etiology. Elevated plasma copeptin in HF has been associated with adverse outcomes such as increased mortality, risk of hospitalization and correlates with the severity of HF. Copeptin may add prognostic information to already established predictors such as clinical variables and natriuretic peptides in HF. In addition, copeptin has been found to be a superior marker when compared with BNP and NT-proBNP in HF patients discharged after hospitalization caused by HF or myocardial infarction (MI). The optimal use of copeptin in HF remains unresolved and future appropriately sized and randomized trials must determine the role of copeptin in HF as a marker of adverse outcomes, risk stratification or as a target in biomarker-guided therapy with arginine vasopressin-antagonists in individualized patient treatment and everyday clinical practice.

Diagnostic Accuracy of Copeptin in the Differential Diagnosis of the Polyuria-polydipsia Syndrome: A Prospective Multicenter Study

CONTEXT

The polyuria-polydipsia syndrome comprises primary polydipsia (PP) and central and nephrogenic diabetes insipidus (DI). Correctly discriminating these entities is mandatory, given that inadequate treatment causes serious complications. The diagnostic "gold standard" is the water deprivation test with assessment of arginine vasopressin (AVP) activity. However, test interpretation and AVP measurement are challenging.

OBJECTIVE

The objective was to evaluate the accuracy of copeptin, a stable peptide stoichiometrically cosecreted with AVP, in the differential diagnosis of polyuria-polydipsia syndrome.

DESIGN, SETTING, AND PATIENTS

This was a prospective multicenter observational cohort study from four Swiss or German tertiary referral centers of adults >18 years old with the history of polyuria and polydipsia.

MEASUREMENTS

A standardized combined water deprivation/3% saline infusion test was performed and terminated when serum sodium exceeded 147 mmol/L. Circulating copeptin and AVP levels were measured regularly throughout the test. Final diagnosis was based on the water deprivation/saline infusion test results, clinical information, and the treatment response.

RESULTS

Fifty-five patients were enrolled (11 with complete central DI, 16 with partial central DI, 18 with PP, and 10 with nephrogenic DI). Without prior thirsting, a single baseline copeptin level >21.4 pmol/L differentiated nephrogenic DI from other etiologies with a 100% sensitivity and specificity, rendering a water deprivation testing unnecessary in such cases. A stimulated copeptin >4.9 pmol/L (at sodium levels >147 mmol/L) differentiated between patients with PP and patients with partial central DI with a 94.0% specificity and a 94.4% sensitivity. A stimulated AVP >1.8 pg/mL differentiated between the same categories with a 93.0% specificity and a 83.0% sensitivity.

LIMITATION

This study was limited by incorporation bias from including AVP levels as a diagnostic criterion.

CONCLUSION

Copeptin is a promising new tool in the differential diagnosis of the polyuria-polydipsia syndrome, and a valid surrogate marker for AVP. Primary Funding Sources: Swiss National Science Foundation, University of Basel.

New prognostic markers in liver cirrhosis

Determining the prognosis of cirrhotic patients is not an easy task. Prognostic scores, like Child-Pugh and Model of End-stage Liver Disease scores, are commonly used by hepatologists, but do not always reflect superimposed events that may strongly influence the prognosis. Among them, bacterial intestinal translocation is a key phenomenon for the development of cirrhosis-related complications. Several biological variables (C-reactive protein, serum free cortisol, copeptin, von Willebrand factor antigen) are surrogates of "inflammatory stress" and have recently been identified as potential prognostic markers in cirrhotic patients. Most of these above mentioned markers were investigated in pilot studies with sometimes a modest sample size but allow us to catch a glimpse of the pathophysiological mechanisms leading to the worsening of cirrhosis. These new data should generate further well-designed studies to better assess the benefit for liver function of preventing intestinal bacterial translocation and microvascular thrombosis. The control of infection is vital and among all actors of immunity, vitamin D also appears to act as an anti-infective agent and therefore has probably a prognostic value.

Changes in Plasma Copeptin Levels during Hemodialysis: Are the Physiological Stimuli Active in Hemodialysis Patients?

OBJECTIVES

Plasma levels of copeptin, a surrogate marker for the vasoconstrictor hormone arginine vasopressin (AVP), are increased in hemodialysis patients. Presently, it is unknown what drives copeptin levels in hemodialysis patients. We investigated whether the established physiological stimuli for copeptin release, i.e. plasma osmolality, blood volume and mean arterial pressure (MAP), are operational in hemodialysis patients.

METHODS

One hundred and eight prevalent, stable hemodialysis patients on a thrice-weekly dialysis schedule were studied during hemodialysis with constant ultrafiltration rate and dialysate conductivity in this observational study. Plasma levels of copeptin, sodium, MAP, and blood volume were measured before, during and after hemodialysis. Multivariate analysis was used to determine the association between copeptin (dependent variable) and the physiological stimuli plasma sodium, MAP, excess weight as well as NT-pro-BNP immediately prior to dialysis and between copeptin and changes of plasma sodium, MAP and blood volume with correction for age, sex and diabetes during dialysis treatment.

RESULTS

Patients were 63 ± 15.6 years old and 65% were male. Median dialysis vintage was 1.6 years (IQR 0.7-4.0). Twenty-three percent of the patients had diabetes and 82% had hypertension. Median predialysis copeptin levels were 141.5 pmol/L (IQR 91.0-244.8 pmol/L). Neither predialysis plasma sodium levels, nor NT-proBNP levels, nor MAP were associated with predialysis copeptin levels. During hemodialysis, copeptin levels rose significantly (p<0.01) to 163.0 pmol/L (96.0-296.0 pmol/L). Decreases in blood volume and MAP were associated with increases in copeptin levels during dialysis, whereas there was no significant association between the change in plasma sodium levels and the change in copeptin levels.

CONCLUSIONS

Plasma copeptin levels are elevated predialysis and increase further during hemodialysis. Volume stimuli, i.e. decreases in MAP and blood volume, rather than osmotic stimuli, are associated with change in copeptin levels during hemodialysis.

Coordinated Regulation of Vasopressin Inactivation and Glucose Uptake by Action of TUG Protein in Muscle

In adipose and muscle cells, insulin stimulates the exocytic translocation of vesicles containing GLUT4, a glucose transporter, and insulin-regulated aminopeptidase (IRAP), a transmembrane aminopeptidase. A substrate of IRAP is vasopressin, which controls water homeostasis. The physiological importance of IRAP translocation to inactivate vasopressin remains uncertain. We previously showed that in skeletal muscle, insulin stimulates proteolytic processing of the GLUT4 retention protein, TUG, to promote GLUT4 translocation and glucose uptake. Here we show that TUG proteolysis also controls IRAP targeting and regulates vasopressin action in vivo. Transgenic mice with constitutive TUG proteolysis in muscle consumed much more water than wild-type control mice. The transgenic mice lost more body weight during water restriction, and the abundance of renal AQP2 water channels was reduced, implying that vasopressin activity is decreased. To compensate for accelerated vasopressin degradation, vasopressin secretion was increased, as assessed by the cosecreted protein copeptin. IRAP abundance was increased in T-tubule fractions of fasting transgenic mice, when compared with controls. Recombinant IRAP bound to TUG, and this interaction was mapped to a short peptide in IRAP that was previously shown to be critical for GLUT4 intracellular retention. In cultured 3T3-L1 adipocytes, IRAP was present in TUG-bound membranes and was released by insulin stimulation. Together with previous results, these data support a model in which TUG controls vesicle translocation by interacting with IRAP as well as GLUT4. Furthermore, the effect of IRAP to reduce vasopressin activity is a physiologically important consequence of vesicle translocation, which is coordinated with the stimulation of glucose uptake.

Urine and plasma osmolality in patients with autosomal dominant polycystic kidney disease: reliable indicators of vasopressin activity and disease prognosis?

BACKGROUND

Vasopressin plays an essential role in osmoregulation, but has deleterious effects in patients with ADPKD. Increased water intake to suppress vasopressin activity has been suggested as a potential renoprotective strategy. This study investigated whether urine and plasma osmolality can be used as reflection of vasopressin activity in ADPKD patients.

METHODS

We measured urine and plasma osmolality, plasma copeptin concentration, total kidney volume (TKV, by MRI) and GFR ((125)I-iothalamate). In addition, change in estimated GFR (eGFR) during follow-up was assessed.

RESULTS

Ninety-four patients with ADPKD were included (56 males, age 40 ± 10, mGFR 77 ± 32 ml/min/1.73 m(2), TKV 1.55 (0.99-2.40) l. Urine osmolality, plasma osmolality and copeptin concentration were 420 ± 195, 289 ± 7 mOsmol/l and 7.3 (3.2-14.6) pmol/l, respectively. Plasma osmolality was associated with copeptin concentration (R = 0.54, p < 0.001), whereas urine osmolality was not (p = 0.4). In addition, urine osmolality was not associated with TKV (p = 0.3), in contrast to plasma osmolality (R = 0.52, p < 0.001) and copeptin concentration (R = 0.61, p < 0.001). Fifty-five patients were followed for 2.8 ± 0.8 years. Baseline plasma and urine osmolality were not associated with change in eGFR (p = 0.6 and p = 0.3, respectively), whereas baseline copeptin concentration did show an association with change in eGFR, in a crude analysis (St. β = -0.41, p = 0.003) and also after adjustment for age, sex and TKV (St. β = -0.23, p = 0.05).

CONCLUSIONS

These data suggest that neither urine nor plasma osmolality are valid measures to identify ADPKD patients that may benefit from increasing water intake. Copeptin appears a better alternative for this purpose.

Copeptin testing in acute myocardial infarction: ready for routine use?

Suspected acute myocardial infarction is one of the leading causes of admission to emergency departments. In the last decade, biomarkers revolutionized the management of patients with suspected acute coronary syndromes. Besides their pivotal assistance in timely diagnosis, biomarkers provide additional information for risk stratification. Cardiac troponins I and T are the most sensitive and specific markers of acute myocardial injury. Nonetheless, in order to overcome the remaining limitations of these markers, novel candidate biomarkers sensitive to early stage of disease are being extensively investigated. Among them, copeptin, a stable peptide derived from the precursor of vasopressin, emerged as a promising biomarker for the evaluation of suspected acute myocardial infarction. In this review, we summarize the currently available evidence for the usefulness of copeptin in the diagnosis and risk stratification of patients with suspected acute myocardial infarction in comparison with routine biomarkers.

Renal function interferes with copeptin in prediction of major adverse cardiac events in patients undergoing vascular surgery

OBJECTIVE

Precise perioperative risk stratification is important in vascular surgery patients who are at high risk for major adverse cardiovascular events (MACE) peri- and postoperatively. In clinical practice, the patient's perioperative risk is predicted by various indicators, e.g. revised cardiac index (RCRI) or modifications thereof. Patients suffering from chronic kidney disease (CKD) are stratified into a higher risk category. We hypothesized that Copeptin as a novel biomarker for hemodynamic stress could help to improve the prediction of perioperative cardiovascular events in patients undergoing vascular surgery including patients with chronic kidney disease.

METHODS

477 consecutive patients undergoing abdominal aortic, peripheral arterial or carotid surgery from June 2007 to October 2012 were prospectively enrolled. Primary endpoint was 30-day postoperative major adverse cardiovascular events (MACE).

RESULTS

41 patients reached the primary endpoint, including 63.4% aortic, 26.8% carotid, and 9.8% peripheral surgeries. Linear regression analysis showed that RCRI (P< .001), pre- (P< .001), postoperative Copeptin (P< .001) and Copeptin level change (P= .001) were associated with perioperative MACE, but CKD remained independently associated with MACE and Copeptin levels. Multivariate regression showed that increased Copeptin levels added risk predictive information to the RCRI (P= .003). Especially in the intermediate RCRI categories was Copeptin significantly associated with the occurrence of MACE. (P< .05 Kruskal Wallis test). Subdivision of the study cohort into CKD stages revealed that preoperative Copeptin was significantly associated with CKD stages (P< .0001) and preoperative Copeptin measurements could not predict MACE in patients with more severe CKD stages.

CONCLUSION

Preoperative Copeptin loses its risk predictive potential for perioperative MACE in patients with chronic kidney disease undergoing vascular surgery.

Prognostic value of copeptin in patients with acute stroke

CONTEXT

There is a need to improve stroke care through the prompt identification of stroke patients at increased risk of an adverse outcome.

OBJECTIVE

To evaluate the prognostic value of copeptin in patients with stroke.

METHODS

We systematically searched PubMed and Embase for relevant studies. Poor outcome and mortality were analyzed.

RESULTS

Twelve studies, containing 2682 patients, were included. Pooled analysis showed that copeptin is an independent prognostic marker of poor outcome after acute stroke and there is a borderline effect of copeptin in predicting mortality after acute stroke.

CONCLUSIONS

Copeptin is an independent predictor of poor outcome and mortality for patients with acute stroke.

Gender-specific co-activation of arginine vasopressin and the hypothalamic-pituitary-adrenal axis during stress

OBJECTIVE

To study the interaction between copeptin and hypothalamic-pituitary-adrenal (HPA) activation in men and women during hypoglycaemic stress.

DESIGN AND PATIENTS

A prospective study in 118 patients (mean age 47·7 ± 13·6 years, n = 52 women) undergoing insulin tolerance testing for suspected pituitary dysfunction.

MEASUREMENTS

Serum copeptin was measured in serially collected blood samples and assessed in relation to ACTH, cortisol and other endocrine parameters.

RESULTS

Symptomatic hypoglycaemia (mean glucose nadir, 1·6 ± 0·5 mmol/l) resulted in a rapid significant increase of serum copeptin. Individuals with impaired pituitary function had lower stress-induced copeptin levels (median, 6·26 pmol/l) than patients with intact pituitary (8·46 pmol/l, P < 0·001). A weak overall correlation between stress-induced copeptin and cortisol levels was observed (rs  = 0·31, P < 0·001). In female individuals, there was a positive correlation between stress-induced copeptin and ACTH (rs  = 0·47, P < 0·001) or cortisol levels (rs  = 0·42, P = 0·002), while in males, no correlation with ACTH levels (rs  = 0·03, P = 0·75) and poor correlation with cortisol levels (rs  = 0·24, P = 0·045) was observed. Patients with central diabetes insipidus showed lowest baseline (2·20 pmol/l) and stimulated copeptin levels (3·68 pmol/l).

CONCLUSIONS

The data from this study indicate that stress-induced release of AVP in women, but not in men, is linked to the co-activation of the hypothalamic-pituitary-adrenal system.

[Usefulness of copeptin in discarding non-ST elevation acute myocardial infarction in patients with acute chest pain and negative first troponin I]

AIM

To evaluate the usefulness of copeptin as a rapid and reliable marker for discarding non-ST elevation acute myocardial infarction (NSTEMI) in patients attended in an Emergency Care Department due to acute chest pain with a normal or non-diagnostic electrocardiogram and a negative first troponin I result.

DESIGN

A prospective observational study was carried out.

SETTING

The Emergency Care Department of a university hospital.

PATIENTS

The study comprised a total of 97 patients attended in the Emergency Care Department due to chest pain suggestive of acute coronary syndrome with an evolution of under 12h, a non-diagnostic electrocardiogram and a negative first troponin I result.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Patient demographic data and baseline characteristics, copeptin upon admission, troponin I upon admission and after 6h, and final diagnosis.

RESULTS

The final diagnosis was NSTEMI in 14 patients (14.4%) -no significant differences in copeptin concentration being observed between the 2 groups, though a tendency towards higher values was recorded in the NSTEMI group (median: 24.6pmol/l [interquartile range: 42.0] vs. 12.0pmol/l [16.1]; P=.06). The AUC ROC for copeptin upon admission was 0.657 (95%CI: 0.504-0.810), with a negative predictive value of 92% for a cutoff point of 14pmol/l.

CONCLUSIONS

Copeptin determination upon admission to the Emergency Care Department in patients with chest pain for ≤12h, suggestive of acute coronary syndrome, with a non-diagnostic electrocardiogram and a negative first troponin I determination does not allow rapid and reliable exclusion of the presence of NSTEMI. Serial troponin I measurements are needed in this respect.

The role of copeptin as a novel cardiovascular biomarker

Copeptin is a provasopressin-derived peptide, the precursor for arginine vasopressin (AVP), which is an antidiuretic hormone from the hypothalamus. Copeptin is secreted together with AVP equally as a response of AVP stimulation. While AVP’s main function is water and blood volume regulation and maintaining electrolyte homeostasis, copeptin’s function is still not fully understood. AVP, copeptin, and other vasopressinergic neuropeptides’ levels are elevated in acute stress caused by pathological conditions. Clinical use of AVP levels has many weaknesses. Copeptin can act as a replacement because of its molecular stability, easier testing methods, and faster results. For example, combination of copeptin and cardiac troponins can eliminate myocardial infarction (MI) diagnosis faster, while combined with brain-type natriuretic peptide (BNP) or its precursor can predict heart failure (HF) outcome. In cardiovascular shock, copeptin levels are elevated. As such, copeptin is a potential biomarker for MI diagnosis and predictor for HF mortality and morbidity. 

Endocrine dysfunction in sepsis: a beneficial or deleterious host response?

Sepsis is a systemic, deleterious inflammatory host response triggered by an infective agent leading to severe sepsis, septic shock and multi-organ failure. The host response to infection involves a complex, organized and coherent interaction between immune, autonomic, neuroendocrine and behavioral systems. Recent data have confirmed that disturbances of the autonomic nervous and neuroendocrine systems could contribute to sepsis-induced organ dysfunction. Through this review, we aimed to summarize the current knowledge about the endocrine dysfunction as response to sepsis, specifically addressed to vasopressin, copeptin, cortisol, insulin and leptin. We searched the following readily accessible, clinically relevant databases: PubMed, UpToDate, BioMed Central. The immune system could be regarded as a "diffuse sensory organ" that signals the presence of pathogens to the brain through different pathways, such as the vagus nerve, endothelial activation/dysfunction, cytokines and neurotoxic mediators and the circumventricular organs, especially the neurohypophysis. The hormonal profile changes substantially as a consequence of inflammatory mediators and microorganism products leading to inappropriately low levels of vasopressin, sick euthyroid syndrome, reduced adrenal responsiveness to ACTH, insulin resistance, hyperglycemia as well as hyperleptinemia. In conclusion, clinical diagnosis of this "pan-endocrine illness" is frequently challenging due to the many limiting factors. The most important benefits of endocrine markers in the management of sepsis may be reflected by their potential to be used as biomarkers in different scoring systems to estimate the severity of the disease and the risk of death.

Association of arginine vasopressin surrogate marker urinary copeptin with severity of autosomal dominant polycystic kidney disease (ADPKD)

BACKGROUND

Experimental studies suggest a detrimental role for cyclic adenosine monophosphate (cAMP) and vasopressin in the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD). It is unknown, however, whether urinary cAMP and copeptin concentration are associated with disease severity in patients with ADPKD.

METHODS

Urinary cAMP (u-cAMP) and copeptin concentration (u-copeptin) were measured by immunoassay in ADPKD patients with CKD stage ≤4. We compared our measurements with clinical parameters including estimated glomerular filtration rate (eGFR), total kidney volume (TKV), and height-adjusted TKV (htTKV). Logarithmic transformation of all variables was performed to fulfill the requirement of equal distribution of the residuals.

RESULTS

We included 50 patients in this study (24 females and 26 males; mean age: 49.3 years). The median eGFR and TKV were 53.2 ml/min/1.73 m(2) (interquartile range: IQR; 29.4-68.45) and 1138.1 ml (IQR; 814.7-2065.0), respectively. The median u-copeptin level was 12.19 (IQR; 6.91-22.32) ng/ml. Although u-cAMP/u-Cr was not significantly correlated with TKV (R = -0.006, p = 0.967) and eGFR (R = 0.077, p = 0.602), urinary copeptin/u-Cr was statistically associated with the various markers of disease severity in ADPKD [positively with TKV (R = 0.351, p = 0.014), htTKV (R = 0.383, p = 0.008) and negatively with eGFR (R = -0.304, p = 0.036)].

CONCLUSIONS

In ADPKD subjects, a higher u-copeptin is associated with disease progression, suggesting that u-copeptin may be a new surrogate marker to predict renal prognosis in ADPKD.

Beyond cardiac troponin: recent advances in the development of alternative biomarkers for cardiovascular disease

Biomarkers complement clinical assessment, electrocardiogram and cardiac imaging in the diagnosis, risk stratification, triage and management of patients with suspected acute cardiovascular diseases. While there is broad consensus that cardiac troponin is the preferred biomarker in clinical practice for the detection of cardiomyocyte damage, the role of alternative biomarkers is less clear. In fact, despite high quality basic and clinical research by hundreds of groups worldwide, only a single new alternative cardiovascular biomarker (natriuretic peptides) has managed to achieve widespread clinical acceptance and inclusion in contemporary clinical practice guidelines in the last decade. This review aims to discuss the remaining unmet needs (and hence opportunities for new biomarkers) in two major clinical areas: early diagnosis of acute myocardial infarction; and early diagnosis and management of acute heart failure, and to evaluate in detail selected alternative biomarkers and recent insights gained from measuring novel biomarkers in large randomized treatment studies in patients with stable coronary artery disease, a setting in which alternative biomarkers may play a more prominent role in the future.

Randomised, double-blind, placebo-controlled, dose-escalating phase I study of QGC001, a centrally acting aminopeptidase a inhibitor prodrug

BACKGROUND AND OBJECTIVES

Inhibition of brain aminopeptidase A (APA), which converts angiotensin II into angiotensin III, has emerged as a novel antihypertensive treatment, as demonstrated in several experimental animal models. QGC001 (originally named RB150) is a prodrug of the specific and selective APA inhibitor EC33, and as such it is the prototype of a new class of centrally acting antihypertensive agents. Given by the oral route in hypertensive rats, it enters the brain and generates EC33, which blocks the brain renin-angiotensin system activity and normalises blood pressure. The aim of the present study was to evaluate the safety, pharmacokinetics and pharmacodynamic effects of QGC001 in humans.

DESIGN AND METHODS

Fifty-six healthy male volunteers were randomly assigned to receive in double-blind and fasted conditions single oral doses of 10, 50, 125, 250, 500, 750, 1,000 and 1,250 mg of QGC001 (n = 6/dose) or placebo (n = 2/dose). We measured plasma and urine concentrations of both QGC001 and EC33 by liquid chromatography-tandem mass spectrometry, plasma renin concentrations (PRC), plasma and free urine aldosterone (PAldo and UAldo), plasma copeptine (PCop), and plasma and urine cortisol (PCort and UCort) concentrations, and supine systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) at various time points.

RESULTS

All doses of QGC001 were clinically and biologically well-tolerated. Peak plasma concentrations (Cmax) of QGC001 and EC33 increased linearly with the dose, with a median time to reach Cmax (tmax) of 1.5 h for QGC001 and 3.0 h for EC33. The median plasma elimination half-life of QGC001 was 1.6 h consistently throughout doses. Urinary excretion of QGC001 and EC33 was below 2% of the administered dose. When compared with placebo, QGC001 did not significantly change PRC, PAldo, UAldo, PCop, PCort or UCort. No significant change was observed for supine HR, SBP and DBP in any treatment group.

CONCLUSION

Single oral administration of QGC001 up to 1,250 mg in healthy volunteers was well-tolerated. Following oral administration, QGC001 is absorbed via the gastrointestinal tract and converted partially into its active metabolite EC33 in plasma. As in animal experiments, in normotensive subjects QGC001 had no effect on the systemic renin-angiotensin-aldosterone parameters and on PCop concentrations, a marker of vasopressin release. In normotensive subjects, a single dose of QCG001 had no effect on SBP, DBP or HR. These data support further evaluation of multiple oral doses of QGC001 in human volunteers and its clinical efficacy in hypertensive patients.

Copeptin concentrations during psychological stress: the PsyCo study

OBJECTIVE

The prognostic/diagnostic biomarker copeptin, an arginine vasopressin surrogate, reflects physical stress. Whether copeptin concentration increases upon psychological stress is unknown. We investigated psychological stress effects on copeptin secretion in healthy volunteers and patients with central diabetes insipidus (DI).

DESIGN

A prospective observational study was conducted to study the relation between copeptin concentration and psychological stress.

METHODS

A total of 20 healthy adults (ten female) and eight patients with central DI (four female) underwent the Trier Social Stress Test including, in order, 30-min waiting period, 10-min anticipation period, 10-min test period and 40-min recovery. Serum copeptin and cortisol concentrations and self-rated stress component feelings were determined in the pre-/post-anticipation period, post-test period and twice post-recovery.

RESULTS

In healthy volunteers, the median (25th-75th percentile) copeptin concentration peaked immediately during the post-test period at 5.1 (3.2-7.0) pmol/l, vs 3.7 (2.6-5.4) pmol/l at baseline. Over the measurement course, copeptin concentration significantly elevated (coefficient; 95% CI) (0.14; 0.06-0.23, P=0.002). The important predictors of increase in copeptin concentration were feelings of tension (0.06; 0.04-0.08, P<0.001) and avoidance (0.07; 0.04-0.10; P<0.001). Copeptin and cortisol levels were associated (0.43; 0.13-0.72, P<0.005). Patients with DI had lower baseline concentrations (1.55 (1.2-3.1) pmol/l) when compared with healthy volunteers, P=0.006. Patients with DI showed no increase upon psychological stress (peak 2.15 pmol/l (1.5-2.28), P=0.79). By contrast, cortisol values were similar in patients and volunteers.

CONCLUSIONS

In healthy volunteers, copeptin levels significantly increased after psychological stress testing; this response was blunted in patients with DI.

Modifiable factors associated with copeptin concentration: a general population cohort

BACKGROUND

Vasopressin plays an important role in maintaining volume homeostasis. However, recent studies suggest that vasopressin also may play a detrimental role in the progression of chronic kidney disease. It therefore is of interest to identify factors that influence vasopressin concentration, particularly modifiable ones.

STUDY DESIGN

Cross-sectional analyses.

SETTING & PARTICIPANTS

Data used are from participants in a large general-population cohort study (Prevention of Renal and Vascular Endstage Disease [PREVEND]). Patients with a missing copeptin value (n=888), nonfasting blood sample (n=495), missing or assumed incorrect 24-hour urine collection (n=388), or heart failure (n=20) were excluded, leaving 6,801 participants for analysis.

FACTOR

Identification of lifestyle- and diet-related factors that are associated with copeptin concentration.

OUTCOMES

Copeptin concentration as surrogate for vasopressin.

MEASUREMENTS

Copeptin was measured by an immunoluminometric assay as a surrogate for vasopressin. Associations were assessed in uni- and multivariable linear regression analyses.

RESULTS

Median copeptin concentration was 4.7 (IQR, 2.9-7.6) pmol/L. When copeptin was studied as a dependent variable, the final stepwise backward model revealed associations with higher copeptin concentrations for lower 24-hour urine volume (P < 0.001), higher sodium excretion (P < 0.001), higher systolic blood pressure (P < 0.001), current smoking (P < 0.001), higher alcohol use (P < 0.001), higher urea excretion (P = 0.003), lower potassium excretion (P = 0.002), use of glucose-lowering drugs (P = 0.02), higher body mass index (P < 0.001), and higher plasma glucose level (P < 0.001). No associations with copeptin concentration were found for C-reactive protein or use of diuretics or nondiuretic antihypertensives.

LIMITATIONS

The cross-sectional study design does not allow firm conclusions on cause-effect relationships.

CONCLUSIONS

Important lifestyle- and diet-related factors associated with copeptin concentration are current smoking, alcohol use, protein and potassium intake, and particularly fluid and sodium intake. These data form a rationale to investigate whether intervening on these factors results in a lower vasopressin concentration with concomitant beneficial renal effects.

Copeptin and arginine vasopressin at high altitude: relationship to plasma osmolality and perceived exertion

PURPOSE

A diuresis is a key part of acclimatisation to high altitude (HA). Arginine vasopressin (AVP) is a hormone involved in salt and water balance and may potentially have a role in the development of altitude illness. ProAVP (copeptin) is more stable than AVP and is assayed by a straightforward, automated method. We investigated the relationship of AVP to copeptin and the copeptin response to exercise and altitude illness in a large cohort during a field study at HA.

METHODS

48 subjects took part in a 10-day trek at HA. Venous blood samples were taken at 3,833, 4,450 and 5,129 m post-trek (exercise) and the following day at rest. Daily recordings of symptoms of altitude illness, oxygen saturations and perceived exertion were carried out.

RESULTS

AVP and copeptin levels increased with exercise and correlated closely (ρ 0.621 p < 0.001), this was strongest in the stressed state when AVP secretion was highest, at 5,129 m post-exercise (ρ 0.834 p < 0.001). On two-way ANOVA, both altitude (F = 3.5; p = 0.015) and exercise (F = 10.2; p = 0.002) influenced copeptin levels (interaction F = 2.2; p = 0.08). AVP levels were influenced by exercise (F = 14.4; p = 0.0002) but not altitude (F = 2.0; p = 0.12) with no overall group interactions (F = 1.92.6; p = 0.06). There was no association between copeptin or arginine vasopressin and altitude illness. Copeptin correlated with the Borg RPE score and was significantly higher in the group with a Borg score ≥15 (7.9 vs. 3.7 p < 0.001).

CONCLUSION

We have shown that arginine vasopressin and copeptin levels correlate and are suppressed below 5,129 m. Furthermore, we have demonstrated that exertion, rather than altitude illness or increasing osmolality, is the stimulus for increases in copeptin.

Copeptin as a diagnostic biomarker for sepsis-related deaths

Copeptin has been shown to increase in patients with sepsis, severe sepsis and septic shock. In the study herein described, copeptin was measured in a series of sepsis-related fatalities and control cases that underwent medico-legal investigations. No age-dependent differences in copeptin levels in either sepsis or control cases were observed. No correlation between copeptin concentrations and postmortem interval was identified in either group. Copeptin levels were significantly higher in sepsis cases. Moreover, copeptin concentrations in septic cases correlated with procalcitonin, C-reactive protein and interleukin 6 values. These preliminary findings seem to indicate that copeptin can be reliably measured in biological samples collected during postmortem investigations. These results also suggest that hemodynamic instability associated with sepsis and septic shock can be characterized by copeptin measurement also in the forensic casework.

Copeptin is not a useful biomarker for small-for-gestational-age: a case control study

OBJECTIVE

To investigate copeptin as a biomarker for small-for-gestational-age.

METHODS

We conducted a nested case-control study on maternal copeptin levels measured in gestational week 12 and 19 and risk of small-for-gestational age. Cases were defined as pregnant women who delivered a small-for-gestational-age infant. Small-for-gestational age was defined as a birth weight - 22% or less than expected according to gestational age (n = 39). Controls were pregnant women who delivered a normal-weight infant (n = 119). The copeptin ultrasensitive Kryptor kit (BRAHMS) was used to determine copeptin in maternal serum. We established reference ranges for copeptin by 95% prediction intervals with 90% confidence intervals. Paired and unpaired t-tests were performed to test the null-hypothesis of no difference in copeptin levels within and between the groups.

RESULTS

The reference intervals for copeptin in normal pregnancies were 1.24-5.51 pmol/L (90% confidence intervals on upper and lower limit were 1.13-1.37 and 5.00-6.08 pmol/L) at gestational week 12, and 1.30-5.09 pmol/L (90% confidence intervals were 1.19-1.42 and 4.65-5.57 pmol/L) at gestational week 19. Copeptin levels decreased from week 12-19 in cases (p = 0.02), whereas no change was observed in controls (p = 0.61). We found no difference in copeptin levels in cases compared to controls in gestational week 12 (p = 0.10) and week 19 (p = 0.81).

CONCLUSION

The present study could not demonstrate copeptin as a novel biomarker for small-for-gestational-age.

[Essential cardiac biomarkers in myocardial infarction and heart failure]

With the discovery of novel biomarkers in cardiovascular diseases, over the past decades considerable improvements in diagnosis, risk stratification and patient care could be achieved; however, despite extensive research, only few biomarkers have met the requirements of significantly improving diagnostic or prognostic approaches. Among the most established markers are cardiac troponins and natriuretic peptides, which are recommended in current guidelines for myocardial infarction or heart failure and are routinely used in clinical practice. Cardiac troponins T and I are the preferred biomarkers of choice for definition of myocardial infarction and proved to be prognostically relevant not only in acute coronary syndrome but also in non-cardiac diseases. The natriuretic peptides B-type natriuretic peptide (BNP) and amino-terminal pro-B-type natriuretic peptide (NT-proBNP) aid in diagnosis, risk stratification and monitoring of heart failure. In recent years several new promising markers have been proposed which might add incremental clinical information, most notably copeptin and growth differentiation factor (GDF) 15; however, larger studies are still required before recommendations for routine clinical use can be made.

Cardiac biomarkers for infarct diagnosis and early exclusion of acute coronary syndrome

The acute coronary syndrome (ACS) represents a diagnostic challenge: on the one hand patients need to be quickly identified to initiate treatment and on the other hand early exclusion of patients without ACS is important to relieve patient stress as well as overcrowded emergency departments. A growing number of biomarkers are becoming available to aid physicians with this task. This review gives an overview of the current research concerning early exclusion with an emphasis on the clinically most important biomarker: cardiac troponin.