Nucleotide sequence of cloned cDNA encoding bovine arginine vasopressin-neurophysin II precursor

Exogenous Opioids and the Human Endocrine System: An Endocrine Society Scientific Statement

The use and misuse of opioids are a growing global problem. Although the effects of these drugs on the human endocrine system have been studied for decades, attention on their related clinical consequences, particularly on the hypothalamic-pituitary system and bone health, has intensified over recent years. This Statement appraises research data related to the impact of opioids on the gonadal and adrenal function. Whereas hypogonadism is well recognized as a side effect of opioids, the significance of their inhibitory actions on the hypothalamic-pituitary-adrenal system and the occurrence of clinically relevant adrenal insufficiency is not fully elucidated. The often-inconsistent results of studies investigating how opioids affect the secretion of GH, prolactin, arginine vasopressin, and oxytocin are assessed. The accumulating evidence of opioid actions on bone metabolism and their negative sequelae on bone mineral density and risk of fracture are also reviewed. In each section, available data on diagnostic and management approaches for opioid endocrine sequelae are described. This Statement highlights a plethora of gaps in research associated with the effects and clinical consequences of opioids on the endocrine system. It is anticipated that addressing these gaps will improve the care of people using or misusing opioids worldwide. The Statement is not intended to serve as a guideline or dictate treatment decisions.

Structure and function of neurohypophysial hormones

Vasopressin (VP) and oxytocin (OXT) are neuropeptides that are synthesized in the hypothalamus and stored in/secreted from the neurohypophysis. Although VP and OXT were initially characterized as osmoregulatory and reproductive hormones, respectively, these peptides exert versatile actions not only in peripheral organs but also in the central nervous system via multiple G protein-coupled receptors. Orthologous peptides and receptors have been identified in various animal phyla, reflecting an ancient origin of this hormone family. The aim of this review is to provide basic information on this hormone family and to propose matters to be addressed in future studies. In the earlier sections of this review, we summarize the historical aspect of VP/OXT research as well as the basic features of hormonal peptides and corresponding receptors. The latter sections describe VP/OXT family peptides and their receptors in nonmammalian species, including invertebrates, to introduce the evolutionary aspect of this hormone family. By integrating knowledge from both general and comparative endocrinology perspectives, we highlight current and future research trends about the VP/OXT system.

Impact Factors of Blood Copeptin Levels in Health and Disease States

OBJECTIVE

Copeptin, the C-terminal glycopeptide of provasopressin, is released into the circulation in an equimolar manner with arginine vasopressin (AVP) when fluid homeostasis changes or has somatic stress. Copeptin is considered a potential alternative to AVP due to its advantages in facilitating assays. Although there have been several studies and reviews that have focused on the marker potential of copeptin in diseases involving changes in AVP, studies on its characteristics and factors that may influence its secretion have not been reviewed before.

METHODS

We summarize the influencing factors associated with copeptin levels in healthy and disease states, show the changes in copeptin levels under different physiologic and pathophysiologic conditions, calculate the changes in copeptin levels under different physiologic and pathophysiologic conditions, and compare them according to the type of stimuli. We also report research advances in copeptin changes in the diagnosis and prognosis of endocrine-related diseases.

RESULTS

Males have higher copeptin levels. Decreased copeptin levels are mainly caused by reduced blood volume and some diseases (eg, obesity). Under normal physiologic conditions, the effects of stress, endocrine axis stimulation, and blood volume increase on copeptin levels gradually increase. Under severe disease conditions (eg, sepsis), copeptin would remain at consistently high levels under compound stimuli and these elevated levels are associated with a poor prognosis of the disease.

CONCLUSION

Summarizing the influencing factors of copeptin can help us better understand the biologic features of copeptin and the similarities and differences between AVP and copeptin.

New insights on diagnosis and treatment of AVP deficiency

Arginine vasopressin deficiency (AVP-D) is one of the main entities of the polyuria-polydipsia syndrome. Its correct diagnosis and differentiation from the other two causes - AVP resistance and primary polydipsia - is crucial as this determines the further management of these patients.Over the last years, several new diagnostic tests using copeptin, the stable surrogate marker of AVP, have been introduced. Among them, hypertonic saline stimulated copeptin was confirmed to reliably and safely improve the diagnostic accuracy to diagnose AVP-D. Due to its simplicity, arginine stimulated copeptin was put forward as alternative test procedure. Glucagon-stimulated copeptin also showed promising results, while the oral growth hormone secretagogue Macimorelin failed to provide a sufficient stimulus. Interestingly, an approach using machine learning techniques also showed promising results concerning diagnostic accuracy.Once AVP-D is diagnosed, further workup is needed to evaluate its etiology. This will partly define the further treatment and management. In general, treatment of AVP-D focuses on desmopressin substitution, with oral formulations currently showing the best tolerance and safety profile. However, in addition to desmopressin substitution, recent data also showed that psychopathological factors play an important role in managing AVP-D patients.

The laboratory investigation of diabetes insipidus: A review

Diabetes insipidus (DI) is a group of disorders that lead to inappropriate production of large volumes of dilute urine. The three main forms are central DI (CDI), nephrogenic DI (NDI) and primary polydipsia (PP). Differentiating CDI/NDI from PP is important as patients with true DI are at risk of severe dehydration without treatment. Biochemical testing is key in the diagnosis of DI. The indirect water deprivation test (WDT) is commonly used in the investigation of DI but has drawbacks including being cumbersome and sometimes producing equivocal results. Direct measurement of AVP has theoretical advantages but has generally only been used in specialist centres. Disadvantages include the requirement to measure AVP under hypertonic stimulation and pre-analytical/analytical challenges. Copeptin (CT-proAVP) is a proxy marker for AVP that is more stable, easier to measure and has been studied more widely in recent years. Historically, the evidence supporting the diagnostic performance of these tests has been relatively poor, being based on a few small, usually single-centre studies. However more recent, well-designed prospective studies are improving the evidence base for investigation of DI. These studies have focused on the utility of copeptin measurements during stimulation tests. There is evidence that measurement of copeptin under stimulation offers improved diagnostic performance compared to the WDT. There is currently a lack of systematic, evidence-based guidelines on the diagnosis of DI, but as the quality of the evidence defining the diagnostic performance of tests for DI continues to improve, a clearer consensus on the optimal approach should become achievable.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

Biosynthesis and Function of VIP and Oxytocin: Mechanisms of C-terminal Amidation, Oxytocin Secretion and Transport

In this review, we provide the status of research on vasoactive intestinal peptide (VIP) and oxytocin, typical C-terminal α-amidated peptide hormones, including their precursor protein structures, processing and C-terminal α-amidation, and the recently identified mechanisms of regulation of oxytocin secretion and its transportation through the blood brain barrier. More than half of neural and endocrine peptides, such as VIP and oxytocin, have the α-amide structure at their C-terminus, which is essential for biological activities. We have studied the synthesis and function of C-terminal α-amidated peptides, including VIP and oxytocin, since the 1980s. Human VIP mRNA encoded not only VIP but also another related C-terminal α-amidated peptide, PHM-27 (peptide having amino-terminal histidine, carboxy-terminal methionine amide, and 27 amino acid residues). The human VIP/PHM-27 gene is composed of 7 exons and regulated synergistically by cyclic AMP and protein kinase C pathways. VIP has an essential role in glycemic control using transgenic mouse technology. The peptide C-terminal α-amidation proceeded through a 2-step mechanism catalyzed by 2 different enzymes encoded in a single mRNA. In the oxytocin secretion from the hypothalamus/the posterior pituitary, the CD38-cyclic ADP-ribose signal system, which was first established in the insulin secretion from pancreatic β cells of the islets of Langerhans, was found to be essential. A possible mechanism involving RAGE (receptor for advanced glycation end-products) of the oxytocin transportation from the blood stream into the brain through the blood-brain barrier has also been suggested.

The role of copeptin in kidney disease

Copeptin is a 39-amino acid glycopeptide that is secreted equimolecularly with arginine-vasopressin (AVP) from the prepro-hormone AVP in the posterior pituitary. While AVP is a very unstable molecule and is accompanied by significant technical troubles in its quantification, copeptin is a stable and easily quantifiable molecule. For this reason, circulating copeptin is currently used as a surrogate for AVP in different pathological conditions, including renal diseases. In recent years it has been shown that copeptin is associated with an increased risk of developing chronic kidney disease in the general population. In addition, copeptin has also been associated with multiple renal diseases with relevant clinical consequences and potential therapeutic implications. In the present review, we update and summarize the clinical significance of copeptin as a surrogate marker for AVP concentrations in different kidney diseases, as well as in renal replacement therapy (hemodialysis and peritoneal dialysis) and renal transplantation.

Norepinephrine innervation of the supraoptic nucleus contributes to increased copeptin and dilutional hyponatremia in male rats

Dilutional hyponatremia associated with liver cirrhosis is due to inappropriate release of arginine vasopressin (AVP). Elevated plasma AVP causes water retention resulting in a decrease in plasma osmolality. Cirrhosis, in this study caused by ligation of the common bile duct (BDL), leads to a decrease in central vascular blood volume and hypotension, stimuli for nonosmotic AVP release. The A1/A2 neurons stimulate the release of AVP from the supraoptic nucleus (SON) in response to nonosmotic stimuli. We hypothesize that the A1/A2 noradrenergic neurons support chronic release of AVP in cirrhosis leading to dilutional hyponatremia. Adult, male rats were anesthetized with 2-3% isoflurane (mixed with 95% O2/5% CO2) and injected in the SON with anti-dopamine β-hydroxylase (DBH) saporin (DSAP) or vehicle followed by either BDL or sham surgery. Plasma copeptin, osmolality, and hematocrit were measured. Brains were processed for ΔFosB, dopamine β-hydroxylase (DBH), and AVP immunohistochemistry. DSAP injection: 1) significantly reduced the number of DBH immunoreactive A1/A2 neurons (A1, P < 0.0001; A2, P = 0.0014), 2) significantly reduced the number of A1/A2 neurons immunoreactive to both DBH and ΔFosB positive neurons (A1, P = 0.0015; A2, P < 0.0001), 3) reduced the number of SON neurons immunoreactive to both AVP and ΔFosB (P < 0.0001), 4) prevented the increase in plasma copeptin observed in vehicle-injected BDL rats (P = 0.0011), and 5) normalized plasma osmolality and hematocrit (plasma osmolality, P = 0.0475; hematocrit, P = 0.0051) as compared with vehicle injection. Our data suggest that A1/A2 neurons contribute to increased plasma copeptin and hypoosmolality in male BDL rats.

Biomarkers for Non-Invasive Stratification of Coronary Artery Disease and Prognostic Impact on Long-Term Survival in Patients with Stable Coronary Heart Disease

Knowledge about cardiac and inflammatory biomarkers in patients with stable coronary artery disease (CAD) is limited. To address this, we analyzed 3072 patients (36% female) with a median follow-up of 10 years in the Leipzig LIFE Heart Study with suspected CAD with coronary angiography. Selected biomarkers included troponin T (hsTNT), N-terminal pro B-type natriuretic peptide (NT-proBNP), copeptin, C-reactive protein (hsCRP), and interleukin-6 (IL-6). Patients were stratified by CAD severity: CAD0 (no sclerosis), CAD1 (non-obstructive, i.e., stenosis < 50%), and CAD2 (≥one stenosis ≥ 50%). Group comparison (GC) included GC1: CAD0 + 1 vs. CAD2; GC2: CAD0 vs. CAD1 + 2. CAD0, CAD1, and CAD2 were apparent in 1271, 631, and 1170 patients, respectively. Adjusted for classical risk factors, hs-cTnT, NT-proBNP, and IL-6 differed significantly in both GC and hsCRP only in GC2. After multivariate analysis, hs-cTnT, NT-proBNP, and IL-6 remained significant in GC1. In GC2, hs-cTnT (p < 0.001) and copeptin (p = 0.014) reached significance. Ten-year survival in groups CAD0, CAD1, and CAD2 was 88.3%, 77.3%, and 72.4%. Incorporation of hs-cTnT, NT-proBNP, copeptin, and IL-6 improved risk prediction (p < 0.001). The studied cardiac and inflammatory biomarkers enable fast and precise non-invasive identification of mortality risk in CAD patients, allowing the tailoring of primary and secondary CAD prevention.

Copeptin as a Diagnostic and Prognostic Biomarker in Cardiovascular Diseases

Copeptin is the carboxyl-terminus of the arginine vasopressin (AVP) precursor peptide. The main physiological functions of AVP are fluid and osmotic balance, cardiovascular homeostasis, and regulation of endocrine stress response. Copeptin, which is released in an equimolar mode with AVP from the neurohypophysis, has emerged as a stable and simple-to-measure surrogate marker of AVP and has displayed enormous potential in clinical practice. Cardiovascular disease (CVD) is currently recognized as a primary threat to the health of the population worldwide, and thus, rapid and effective approaches to identify individuals that are at high risk of, or have already developed CVD are required. Copeptin is a diagnostic and prognostic biomarker in CVD, including the rapid rule-out of acute myocardial infarction (AMI), mortality prediction in heart failure (HF), and stroke. This review summarizes and discusses the value of copeptin in the diagnosis, discrimination, and prognosis of CVD (AMI, HF, and stroke), as well as the caveats and prospects for the application of this potential biomarker.

Chest pain in the emergency department: From score to core-A prospective clinical study

High-sensitivity troponin assay brought new challenges as we detect elevated concentration in many other diseases, and it became difficult to distinguish the real cause of this elevation. In this notion, diagnosis of acute coronary syndrome (ACS) remains a challenge in emergency department (ED). We aim to examine different approaches for rule-in and rule-out of ACS using risk scores, copeptin, and coronary computed tomography angiography (CCTA). A prospective observational study was designed to evaluate chest pain patients. Consecutive adult patients admitted to the ED with a chief complaint of chest pain due to any cause were included. All patients were followed-up for 6 months after discharge for major adverse cardiovascular events and readmissions. Admission data, ED processes, and diagnoses were analyzed. One hundred forty-six patients were included, average age was 63 ± 13.4 years, and 95 (65.1%) were male. Global Registry of Acute Coronary Events (GRACE) and History, ECG, Age, Risk factors, Troponin (HEART) scores showed good prognostic abilities, but HEART combination with copeptin improves diagnoses of myocardial infarction (area under the curve [AUC] 0.764 vs AUC 0.864 P = .0008). Patients with elevated copeptin were older, had higher risk scores, and were more likely to be admitted to hospital and diagnosed with ACS in ED. For copeptin, AUC was 0.715 (95% confidence interval 0.629-0.803), and for combination with troponin, AUC of 0.770 (0.703-0.855) did not improve rule-in of myocardial infarction. High-sensitivity troponin I assay alongside prior stroke, history of carotid stenosis, dyslipidemia, use of diuretics, and electrocardiogram changes (left bundle branch block or ST depression) are good predictors of myocardial infarction (χ² = 52.29, AUC = 0.875 [0.813-0.937], P < .001). The regression analysis showed that combination of copeptin and CCTA without significant stenosis can be used for ACS rule-out (χ² = 26.36, P < .001, AUC = 0.772 [0.681-0.863], negative predictive value of 96.25%). For rule-in of ACS, practitioner should consider not only scores for risk stratification but carefully analyze medical history and nonspecific electrocardiogram changes and even with normal troponin results, we strongly suggest thorough evaluation in chest pain unit. For rule-out of ACS combination of copeptin and CCTA holds great potential.

The role of vasopressin V1A and oxytocin OTR receptors in protective effects of arginine vasopressin against H2O2-induced oxidative stress in H9C2 cells

BACKGROUND

Oxidative stress, has been shown to play an important role in the pathophysiology of cardiac remodelling and heart failure. The aim of study is effect of arginine vasopressin (AVP) on apoptosis of cardiomyocyte via its receptors.

MATERIALS AND METHODS

The cell viability effect of AVP in H9C2 cardiomyocytes was assayed using the MTT method. The transcription and translation level of apoptosis genes (Bax, Bcl-2, caspase-3) were discovered with qRT-PCR and western blotting.

RESULTS

The results showed that vasopressin could reduce apoptosis in cardiomyocytes cell line through downregulation of caspase-3, BAX and upregulation of Bcl-2 (p < .001). Also, there was a decrease in anti-apoptosis effect of vasopressin when V1A and OTR receptors were blocked with their antagonists.

DISCUSSION

These results suggest that activation of V1A and OTR receptors in H9C2 cells mediate protective effect of vasopressin via regulating apoptosis marker that lead to cell survival under conditions of stress oxidative.Key pointAVP may contribute to the improvement of heart ischaemia through its actions on V1A and OTR receptors.

Approach to the Patient: "Utility of the Copeptin Assay"

Copeptin derives from the same precursor peptide preprovasopressin as arginine vasopressin (AVP). The secretion of both peptides is stimulated by similar physiological processes, such as osmotic stimulation, hypovolemia, or stress. AVP is difficult to measure due to complex preanalytical requirements and due to technical difficulties. In the last years, copeptin was found to be a stable, sensitive, and simple to measure surrogate marker of AVP release. Different immunoassays exist to measure copeptin. The 2 assays which have most often be used in clinical studies are the original sandwich immunoluminometric assay and its automated immunofluorescent successor. In addition, various enzyme-linked immunosorbent assay have been developed. With the availability of the copeptin assay, the differential diagnosis of diabetes insipidus was recently revisited. The goal for this article is therefore to first review the physiology of copeptin, and second to describe its use as marker for the differential diagnosis of vasopressin-dependent fluid disorders, mainly diabetes insipidus but also hyper- and hyponatremia. Furthermore, we highlight the role of copeptin as prognostic marker in other acute and chronic diseases.

Emerging Biomarkers of Multiple Sclerosis in the Blood and the CSF: A Focus on Neurofilaments and Therapeutic Considerations

INTRODUCTION

Multiple Sclerosis (MS) is the most common immune-mediated chronic neurodegenerative disease of the central nervous system (CNS) affecting young people. This is due to the permanent disability, cognitive impairment, and the enormous detrimental impact MS can exert on a patient's health-related quality of life. It is of great importance to recognise it in time and commence adequate treatment at an early stage. The currently used disease-modifying therapies (DMT) aim to reduce disease activity and thus halt disability development, which in current clinical practice are monitored by clinical and imaging parameters but not by biomarkers found in blood and/or the cerebrospinal fluid (CSF). Both clinical and radiological measures routinely used to monitor disease activity lack information on the fundamental pathophysiological features and mechanisms of MS. Furthermore, they lag behind the disease process itself. By the time a clinical relapse becomes evident or a new lesion appears on the MRI scan, potentially irreversible damage has already occurred in the CNS. In recent years, several biomarkers that previously have been linked to other neurological and immunological diseases have received increased attention in MS. Additionally, other novel, potential biomarkers with prognostic and diagnostic properties have been detected in the CSF and blood of MS patients.

AREAS COVERED

In this review, we summarise the most up-to-date knowledge and research conducted on the already known and most promising new biomarker candidates found in the CSF and blood of MS patients.

DISCUSSION

the current diagnostic criteria of MS relies on three pillars: MRI imaging, clinical events, and the presence of oligoclonal bands in the CSF (which was reinstated into the diagnostic criteria by the most recent revision). Even though the most recent McDonald criteria made the diagnosis of MS faster than the prior iteration, it is still not an infallible diagnostic toolset, especially at the very early stage of the clinically isolated syndrome. Together with the gold standard MRI and clinical measures, ancillary blood and CSF biomarkers may not just improve diagnostic accuracy and speed but very well may become agents to monitor therapeutic efficacy and make even more personalised treatment in MS a reality in the near future. The major disadvantage of these biomarkers in the past has been the need to obtain CSF to measure them. However, the recent advances in extremely sensitive immunoassays made their measurement possible from peripheral blood even when present only in minuscule concentrations. This should mark the beginning of a new biomarker research and utilisation era in MS.

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

Copeptin in fluid disorders and stress

Copeptin, a glycosylated peptide of 39 amino acids, is the C-terminal segment of arginine vasopressin (AVP) precursor peptide, which is consisted of two other fragments, vasopressin and neurophysin Ⅱ. The main physiological functions of AVP are fluid and osmotic balance, cardiovascular homeostasis and regulation of the endocrine stress response. Numerous studies have demonstrated that the endogenous AVP in plasma is a meaningful biomarker to guide diagnosis and therapy of diseases associated with fluids disorders and stress. However, due to its instability, short half-time life in circulation and lack of readily available AVP assays, clinical measurement of AVP is restricted. In contrast to AVP, copeptin which is released in an equimolar mode with AVP from the pituitary, has emerged as a stable and simple-to-measure surrogate marker of AVP and displays excellent potential in diagnosis, differentiation and prognosis of various diseases. This review will discuss the studies on the clinical value of copeptin in different diseases, especially in AVP-dependent fluids disorders, as well as issues and prospects of the application of this potential biomarker.

Increased Circulating Copeptin Levels Are Associated with Vaso-Occlusive Crisis and Right Ventricular Dysfunction in Sickle Cell Anemia

OBJECTIVE

Vaso-occlusive crisis (VOC) is a common clinical manifestation of sickle cell anemia (SCA) and is associated with increased proinflammatory mediators. Copeptin is the C-terminal part of the prohormone for provasopressin and seems clinically relevant in various clinical conditions. Right ventricular (RV) dysfunction significantly appears in SCA patients due to pulmonary hypertension. This study aimed to investigate the association of copeptin levels in VOC patients and evaluate RV dysfunction.

MATERIALS AND METHODS

A total of 108 patients were enrolled in the study. Twenty-eight SCA patients in steady state (30.2 ± 0.9 years), 25 SCA patients in VOC (36.8 ± 11.8 years), and 55 healthy individuals (31.9 ± 9.4 years) with HbAA genotype were included. Clinical, echocardiographic, and laboratory data were recorded. ELISA was used for the determination of serum levels of copeptin.

RESULTS

VOC patients had significantly higher copeptin level compared both with controls and SCA subjects in steady state (22.6 ± 13.0 vs. 11.3 ± 5.7 pmol/L, 22.6 ± 13.0 vs. 12.4 ± 5.8 pmol/L, p = 0.009 for both). Additionally, the copeptin level was significantly higher in SCA patients with RV dysfunction than those without RV dysfunction (23.2 ± 12.2 vs. 15.3 ± 9.5 pmol/L, p = 0.024). Multiple logistic regression analysis revealed that high-sensitivity C-reactive protein and copeptin levels were found to be associated with VOC.

CONCLUSION

This study showed that copeptin and hs-CRP levels were increased in patients with VOC, and it was found that RV dysfunction was more common in SCA patients with VOC than in the control group. Copeptin can be considered for use as a potential biomarker in predicting VOC crisis in SCA patients and in the early detection of patients with SCA who have the potential to develop RV dysfunction.

Prognostic performance of copeptin among patients with acute decompensated heart failure

BACKGROUND

In heart failure (HF), various biomarkers have been established for prognosis. However, little is known about the relevance of copeptin measurements to HF. This study aimed to explore the prognostic value of copeptin for predicting cardiovascular (CV) death or HF-related re-hospitalisation in patients with acute decompensated HF.

MATERIALS AND METHODS

We prospectively enrolled 155 consecutive patients with acute signs and symptoms of HF. Plasma copeptin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured at admission. Patients were monitored for 90 days regarding the composite endpoint of CV death or acute HF-related re-hospitalisation.

RESULTS

Of the 155 patients enrolled, 40 reached the endpoint, and 115 were in a stable condition during follow-up. Patients who reached an adverse endpoint showed higher NT-proBNP and copeptin levels compared to patients in stable condition. Receiver operating characteristic curve analysis revealed that the area under curve of copeptin 0.844 (95% CI, 0.753-0.935) was superior to that of NT-proBNP 0.809 (95% CI, 0.729-0.890) for the prediction of adverse events within 90 days. Meanwhile, compared to the group with lower copeptin levels (<34 pmol/L), patients with higher copeptin levels (≥34 pmol/L) were at a 10.672-times higher risk of CV death or acute HF-related re-hospitalisation. Multivariate Cox proportional hazards regression analysis revealed that increased copeptin level was a significantly independent predictor of adverse events (risk ratio, 1.051; 95% CI, 1.020-1.083; p < 0.001).

CONCLUSION

Copeptin was found to be a strong, novel marker for predicting CV death or HF-related re-hospitalisation in patients with acute decompensated HF.

Role of copeptin in the diagnosis of traumatic neuroendocrine dysfunction

Traumatic neuroendocrine dysfunction may present with diabetes insipidus (DI) or with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Both these pathologies involve a disturbance in the antidiuretic hormone (ADH) secretion, causing dysnatremias. Diagnosis of posttraumatic ADH dysfunction is hampered by technical difficulties in ADH assessment, and relies mostly on non-specific serum sodium, serum and urine osmolality and diuresis, often leading to misdiagnosis in the acute care setting. Research now focuses on the diagnostic role of copeptin, a peptide secreted together with ADH in an equimolar fashion, and which can be accurately evaluated. Recent studies identified cut-off values of 2.6 pmol/L for baseline copeptin and of 4.9 and 3.8 pmol/L for hypertonic saline infusion and arginine infusion stimulated copeptin, respectively, for the diagnosis of DI in patients with polyuria-polydipsia syndrome. Although SIADH is more difficult to be explored due to its heterogeneity, a ratio of copeptin to urinary sodium below 30 pmol/mmol identifies euvolemic hyponatremia. Exploring the role of copeptin assessment in patients with traumatic brain injury (TBI) in the acute phase may improve their diagnosis accuracy, management and outcome.

Immunoelectron Microscopic Characterization of Vasopressin-Producing Neurons in the Hypothalamo-Pituitary Axis of Non-Human Primates by Use of Formaldehyde-Fixed Tissues Stored at -25 °C for Several Years

Translational research often requires the testing of experimental therapies in primates, but research in non-human primates is now stringently controlled by law around the world. Tissues fixed in formaldehyde without glutaraldehyde have been thought to be inappropriate for use in electron microscopic analysis, particularly those of the brain. Here we report the immunoelectron microscopic characterization of arginine vasopressin (AVP)-producing neurons in macaque hypothalamo-pituitary axis tissues fixed by perfusion with 4% formaldehyde and stored at −25 °C for several years (4–6 years). The size difference of dense-cored vesicles between magnocellular and parvocellular AVP neurons was detectable in their cell bodies and perivascular nerve endings located, respectively, in the posterior pituitary and median eminence. Furthermore, glutamate and the vesicular glutamate transporter 2 could be colocalized with AVP in perivascular nerve endings of both the posterior pituitary and the external layer of the median eminence, suggesting that both magnocellular and parvocellular AVP neurons are glutamatergic in primates. Both ultrastructure and immunoreactivity can therefore be sufficiently preserved in macaque brain tissues stored long-term, initially for light microscopy. Taken together, these results suggest that this methodology could be applied to the human post-mortem brain and be very useful in translational research.

Association between copeptin levels and treatment responses to hypertonic saline infusion in patients with symptomatic hyponatremia: a prospective cohort study

Background

Copeptin is secreted in equimolar amounts as arginine vasopressin, main hormone regulating body fluid homeostasis. A recent study reported a copeptin-based classification of osmoregulatory defects in syndromes of inappropriate antidiuresis that may aid in prediction of therapeutic success. We investigated usefulness of copeptin for differentiating etiologies of hyponatremia and predicting efficacy and safety of hypertonic saline treatment in hyponatremic patients.

Methods

We performed a multicenter, prospective cohort study of 100 inpatients with symptomatic hyponatremia (corrected serum sodium [sNa] ≤ 125 mmol/L) treated with hypertonic saline. Copeptin levels were measured at baseline and 24 hours after treatment initiation, and patients were classified as being below or above median of copeptin at baseline or at 24 hours, respectively. Correlations between target, under correction, and overcorrection rates of sNa within 24 hours/24–48 hours and copeptin levels at baseline/24 hours were analyzed.

Results

Mean sNa and median copeptin levels were 117.9 and 16.9 pmol/L, respectively. Ratio of copeptin-to-urine sodium allowed for an improved differentiation among some (insufficient effective circulatory volume), but not all hyponatremia etiologic subgroups. Patients with below-median copeptin levels at baseline achieved a higher target correction rate in 6/24 hours (odds ratio [OR], 2.97; p = 0.02/OR, 6.21; p = 0.006). Patients with below-median copeptin levels 24 hours after treatment showed a higher overcorrection rate in next 24 hours (OR, 18.00, p = 0.02).

Conclusion

There is a limited diagnostic utility of copeptin for differential diagnosis of hyponatremia. However, copeptin might be useful for predicting responses to hypertonic saline treatment in hyponatremic patients.

Copeptin combined with National Early Warning Score for predicting survival in elderly critical ill patients at emergency department

OBJECTIVE

Copeptin, reflecting vasopressin release, as well as the National Early Warning Score (NEWS), reflecting the severity of critical illness, might qualify for survival prediction in elderly patients with critical illness. This prospective observational study aims at assessing the predictive value of copeptin combined with NEWS on the prognosis of elderly critical ill patients at emergency department (ED).

METHODS

We analyzed serum copeptin levels and the NEWS at admission to the ED in a prospective, single-center, and observational study comprising 205 elderly patients with critical illness. Death within 30 days after admission to the ED was the primary end point.

RESULTS

The serum copeptin levels and the NEWS in the non-survivor patients group were higher than those in the survivor group [30.35 (14.20, 38.91) vs 17.53 (13.01, 25.20), P = 0.001 and 9.0 (7.0-10.0) vs 7.0 (6.0-8.0), P = 0.001]. Multivariate logistic regression analysis showed that copeptin, NEWS and copeptin combined with NEWS were all independent risk factors for 30-day mortality in elderly patients with critical illness. Copeptin, NEWS and copeptin combined with NEWS all performed well in predicting 30-day survival, with area under the ROC curve (AUC) values of 0.766 (95%CI, 0.702-0.822), 0.797 (95%CI, 0.744-0.877) and 0.854 (95%CI, 0.798-0.899) respectively. Using the Z test to compare the areas under the above three curves, copeptin combined with NEWS showed a higher predictive value for 30-day survival (P < 0.05). As we calculated, the optimal cut-off values of copeptin and NEWS using the Youden index were 19.78 pg/mL and 8.5 points, respectively. Risk stratification analysis showed that patients with both copeptin levels higher than 19.78 pg/mL and NEWS points higher than 8.5 points had the highest risk of death.

CONCLUSIONS

Copeptin combined with NEWS have a stronger predictive power on the prognosis of elderly patients with critical illness at ED, comparing to either factor individually.

Variation of pro-vasopressin processing in parvocellular and magnocellular neurons in the paraventricular nucleus of the hypothalamus: Evidence from the vasopressin-related glycopeptide copeptin

Arginine vasopressin (AVP) is synthesized in parvocellular- and magnocellular neuroendocrine neurons in the paraventricular nucleus (PVN) of the hypothalamus. Whereas magnocellular AVP neurons project primarily to the posterior pituitary, parvocellular AVP neurons project to the median eminence (ME) and to extrahypothalamic areas. The AVP gene encodes pre-pro-AVP that comprises the signal peptide, AVP, neurophysin (NPII), and a copeptin glycopeptide. In the present study, we used an N-terminal copeptin antiserum to examine copeptin expression in magnocellular and parvocellular neurons in the hypothalamus in the mouse, rat, and macaque monkey. Although magnocellular NPII-expressing neurons exhibited strong N-terminal copeptin immunoreactivity in all three species, a great majority (~90%) of parvocellular neurons that expressed NPII was devoid of copeptin immunoreactivity in the mouse, and in approximately half (~53%) of them in the rat, whereas in monkey hypothalamus, virtually all NPII-immunoreactive parvocellular neurons contained strong copeptin immunoreactivity. Immunoelectron microscopy in the mouse clearly showed copeptin-immunoreactivity co-localized with NPII-immunoreactivity in neurosecretory vesicles in the internal layer of the ME and posterior pituitary, but not in the external layer of the ME. Intracerebroventricular administration of a prohormone convertase inhibitor, hexa-d-arginine amide resulted in a marked reduction of copeptin-immunoreactivity in the NPII-immunoreactive magnocellular PVN neurons in the mouse, suggesting that low protease activity and incomplete processing of pro-AVP could explain the disproportionally low levels of N-terminal copeptin expression in rodent AVP (NPII)-expressing parvocellular neurons. Physiologic and phylogenetic aspects of copeptin expression among neuroendocrine neurons require further exploration.

Diabetes insipidus complicating apoplexy during pregnancy: the potential use of copeptin

Pituitary apoplexy during pregnancy is rare but important to recognise, particularly in the hyperoestrogenaemic state when known lactotroph hyperplasia occurs. Untreated, the complication rates from pituitary adenomas depend upon the size of the adenoma before pregnancy. A history of thirst plus polydipsia during pregnancy raises suspicion for diabetes insipidus and a 24-h urine collection quantifying polyuria with an inappropriately low urine osmolality confirms the diagnosis. Further evaluation for assessing diabetes insipidus in pregnancy may be facilitated by the use of a copeptin.

A Subset of Primary Polydipsia, "Dipsogneic Diabetes Insipidus", in Apparently Healthy People Due to Excessive Water Intake: Not Enough Light to Illuminate the Dark Tunnel

Dipsogenic diabetes insipidus (DDI) is a subtype of primary polydipsia (PP), which occurs mostly in healthy people without psychiatric disease. In contrast, PP is characterized by a polyuria polydipsia syndrome (PPS) associated with psychiatric illness. However, the pathogenesis of DDI is not well established and remains unexplored. In order to diagnose DDI, the patient should exhibit excessive thirst as the main symptom, in addition to no history of psychiatric illness, polyuria with low urine osmolality, and intact urine concentrating ability. Treatment options for DDI remain scarce. On this front, there have been two published case reports with successful attempts at treating DDI patients. The noteworthy commonalities in these reports are that the patient was diagnosed with frequent excessive intake of water due to a belief that drinking excess water would have pathologic benefits. It could therefore be hypothesized that the increasing trend of excessive fluid intake in people who are health conscious could also contribute to DDI. Hence, this review provides an overview of the pathophysiology, diagnosis, and treatment, with a special emphasis on habitual polydipsia and DDI.

Copeptin reliably reflects longitudinal right ventricular function

BACKGROUND

Data is limited evaluating novel biomarkers in right ventricular dysfunction. Normal right heart function improves the prognosis of patients with heart failure. Therefore, this study investigates the association between the novel biomarker copeptin and right heart function compared to NT-proBNP.

METHODS

Patients undergoing routine echocardiography were enrolled prospectively. Right ventricular function was assessed by tricuspid annular plane systolic excursion (TAPSE) and further right ventricular and atrial parameters. Exclusion criteria were age under 18 years, left ventricular ejection fraction < 50% and moderate to severe valvular heart disease. Blood samples were taken for biomarker measurements within 72 h of echocardiography.

RESULTS

Ninety-one patients were included. Median values of copeptin increased significantly according to decreasing values of TAPSE (P = 0.001; right heart function grade I: tricuspid annular plane systolic excursion; TAPSE > 24 mm: 5.20 pmol/L; grade II: TAPSE 18-24 mm: 8.10 pmol/L; grade III: TAPSE < 18 mm: 26.50 pmol/L). Copeptin concentrations were able to discriminate patients with decreased right heart function defined as TAPSE < 18 mm (area under the curves [AUC]: copeptin: 0.793; P = 0.001; NT-proBNP: 0.805; P = 0.0001). Within a multivariable linear regression model, copeptin was independently associated with TAPSE (copeptin: T: -4.43; P = 0.0001; NT-proBNP: T: -1.21; P = 0.23). Finally, copeptin concentrations were significantly associated with severely reduced right heart function (TAPSE < 18 mm) within a multivariate logistic regression model (copeptin: odds ratio: 0.94; 95% confidence interval: 0.911-0.975; P = 0.001).

CONCLUSIONS

This study demonstrates that the novel biomarker copeptin reflects longitudinal right heart function assessed by standardized transthoracic echocardiography compared with NT-proBNP.

Vasopressin and copeptin release during sepsis and septic shock

Sepsis is defined as a potentially fatal organ dysfunction caused by a dysregulated host response to infection. Despite tremendous progress in the medical sciences, sepsis remains one of the leading causes of morbidity and mortality worldwide. The host response to sepsis and septic shock involves changes in the immune, autonomic, and neuroendocrine systems. Regarding neuroendocrine changes, studies show an increase in plasma vasopressin (AVP) concentrations followed by a decline, which may be correlated with septic shock. AVP is a peptide hormone derived from a larger precursor (preprohormone), along with two peptides, neurophysin II and copeptin. AVP is synthesized in the hypothalamus, stored and released from the neurohypophysis into the bloodstream by a wide range of stimuli. The measurement of AVP has limitations due to its plasma instability and short half-life. Copeptin is a more stable peptide than AVP, and its immunoassay is feasible. The blood concentrations of copeptin mirror those of AVP in many physiological states; paradoxically, during sepsis-related organ dysfunction, an uncoupling between copeptin and AVP blood levels appears to happen. In this review, we focus on clinical and experimental studies that analyzed AVP and copeptin blood concentrations over time in sepsis. The findings suggest that AVP and copeptin behave similarly in the early stages of sepsis; however, we did not find a proportional decrease in copeptin concentrations as seen with AVP during septic shock. Copeptin levels were higher in nonsurvivors than in survivors, suggesting that copeptin may work as a marker of severity or sepsis-related organ dysfunction.

Copeptin: Prognostic Relevance as a Perioperative Marker in Pediatric Cardiac Surgery

BACKGROUND

Copeptin is a cleavage product of vasopressin. This study aimed to figure out if copeptin would be a suitable biomarker in patients with congenital heart disease in the postoperative course.

METHODS

The primary outcome endpoint of this study was the change in copeptin concentration perioperatively in patients with congenital heart disease after surgery, with the use of a cardiopulmonary bypass. Three blood samples were taken from 81 patients up to 6 years of age in order to evaluate changes in copeptin concentration.

RESULTS

Significant increase of copeptin concentration was shown between the first and second blood draws as well as between the first and third blood draws (Ps < .001). Additionally, positive and significant correlations (r ≥ .27) between the cardiopulmonary bypass times, The Society of Thoracic Surgeons and European Association for Cardio-Thoracic Surgery mortality category, the inotropic score, the duration of mechanical ventilation, the length of stay at the intensive care unit (ICU), the length of stay at the hospital, and the preoperative as well as the ICU copeptin levels were found.

CONCLUSIONS

Copeptin showed a tendency to predict the clinical outcome of patients after congenital heart surgery. Patients with higher copeptin levels underwent more complex procedures, had longer cardiopulmonary bypass times, required more catecholamine support, needed longer time of invasive ventilation, and had longer overall stay and ICU stay.

Central Diabetes Insipidus Caused by Arginine Vasopressin Gene Mutation: Report of a Novel Mutation and Review of Literature

Familial neurohypophyseal diabetes insipidus (FNDI) is an autosomal dominant hereditary disorder characterized by severe polydipsia and polyuria that usually presents in early childhood. In this study, we describe a new arginine vasopressin (AVP) gene mutation in an ethnic German family with FNDI and provide an overview of disease-associated AVP-gene mutations that are already described in literature. Three members of a German family with neurohypophyseal diabetes insipidus were studied. Isolated DNA from peripheral blood samples was used for mutation analysis by sequencing the whole coding region of AVP-NPII gene. Furthermore, we searched the electronic databases MEDLINE (Pubmed) as well as HGMD, LOVD-ClinVar, db-SNP and genomAD in order to compare our cases to that of other patients with FNDI. Genetic analysis of the patients revealed a novel heterozygote missense mutation in exon 2 of the AVP gene (c.274T>G), which has not yet been described in literature. We identified reports of more than 90 disease-associated mutations in the AVP gene in literature. The novel mutation of the AVP gene seems to cause FNDI in the presented German family. Similar to our newly detected mutation, most mutations causing FNDI are found in exon 2 of the AVP gene coding for neurophysin II. Clinically, it is important to think of FNDI in young children presenting with polydipsia and polyuria.

Vasopressin gene products are colocalised with corticotrophin-releasing factor within neurosecretory vesicles in the external zone of the median eminence of the Japanese macaque monkey (Macaca fuscata)

Arginine vasopressin (AVP), when released into portal capillaries with corticotrophin-releasing factor (CRF) from terminals of parvocellular neurones of the hypothalamic paraventricular nucleus (PVH), facilitates the secretion of adrenocorticotrophic hormone (ACTH) in stressed rodents. The AVP gene encodes a propeptide precursor containing AVP, AVP-associated neurophysin II (NPII), and a glycopeptide copeptin, although it is currently unclear whether copeptin is always cleaved from the neurophysin and whether the NPII and/or copeptin have any functional role in the pituitary. Furthermore, for primates, it is unknown whether CRF, AVP, NPII and copeptin are all colocalised in neurosecretory vesicles in the terminal region of the paraventricular CRF neurone axons. Therefore, we investigated, by fluorescence and immunogold immunocytochemistry, the cellular and subcellular relationships of these peptides in the CRF- and AVP-producing cells in unstressed Japanese macaque monkeys (Macaca fuscata). Reverse transcription-polymerase chain reaction analysis showed the expression of both CRF and AVP mRNAs in the monkey PVH. As expected, in the magnocellular neurones of the PVH and supraoptic nucleus, essentially no CRF immunoreactivity could be detected in NPII-immunoreactive (AVP-producing) neurones. Immunofluorescence showed that, in the parvocellular part of the PVH, NPII was detectable in a subpopulation (approximately 39%) of the numerous CRF-immunoreactive neuronal perikarya, whereas, in the outer median eminence, NPII was more prominent (approximately 52%) in the CRF varicosities. Triple immunoelectron microscopy in the median eminence demonstrated the presence of both NPII and copeptin immunoreactivity in dense-cored vesicles of CRF-containing axons. The results are consistent with an idea that the AVP propeptide is processed and NPII and copeptin are colocalised in hypothalamic-pituitary CRF axons in the median eminence of a primate. The CRF, AVP and copeptin are all co-packaged in neurosecretory vesicles in monkeys and are thus likely to be co-released into the portal capillary blood to amplify ACTH release from the primate anterior pituitary.

Copeptin in the differential diagnosis of hypotonic polyuria

COPEPTIN

Copeptin is secreted in equimolar amount to Arginine Vasopressin (AVP) but can easily be measured with a sandwich immunoassay. Both peptides, copeptin and AVP, show a high correlation. Accordingly, copeptin mirrors the amount of AVP in the circulation and its measurement provides an attractive marker in the differential diagnosis of diabetes insipidus.

THE POLYURIA POLYDIPSIA SYNDROME

Diabetes insipidus-either central or nephrogenic-has to be differentiated from primary polydipsia. Differentiation is crucial since wrong treatment can have deleterious consequences. Since many decades, the "gold standard" for differential diagnosis has been the classical water deprivation test, which has several limitations leading to an overall limited diagnostic accuracy. In addition, the test has a long duration of 17 hours and is cumbersome for patients. Clinical signs and symptoms as well as MRI characteristics overlap between patients with diabetes insipidus and primary polydipsia. Direct measurement of AVP upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay.

COPEPTIN AS DIAGNOSTIC TOOL IN THE POLYURIA POLYDIPSIA SYNDROME

We have recently shown that copeptin, without prior water deprivation, identifies patients with nephrogenic diabetes insipidus. On the other hand, for the more difficult differentiation between central diabetes insipidus and primary polydipsia, a copeptin level of 4.9 pmol/L stimulated with hypertonic saline infusion differentiates between these two entities with a high diagnostic accuracy, and is superior to the water deprivation test. It is important to note that close sodium monitoring during the hypertonic saline test is a prerequisite.

CONCLUSION

Therefore, we propose that copeptin upon hypertonic saline infusion should become the new standard test in the differential diagnosis of diabetes insipidus.

Diabetes Insipidus: New Concepts for Diagnosis

Diabetes insipidus (DI), be it from central or from nephrogenic origin, has to be differentiated from primary polydipsia. This differentiation is crucial since wrong treatment can have dangerous consequences. For decades, the "gold standard" for differential diagnosis has been the standard water deprivation test. However, this test has several limitations leading to an overall limited diagnostic accuracy. In addition, the test has a long duration of 17 h and is cumbersome for patients. Also clinical signs and symptoms and MRI characteristics overlap between patients with DI and primary polydipsia. Direct measurement of arginine vasopressin (AVP) upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay. Copeptin is secreted in equimolar ratio to AVP, mirroring AVP concentrations in the circulation. We have shown that copeptin, without prior fluid deprivation, identifies patients with nephrogenic DI. For the more difficult differentiation between central DI and primary polydipsia, a copeptin level of 4.9 pmol/L stimulated with hypertonic saline infusion differentiates between these 2 entities with a high diagnostic accuracy and is superior to the water deprivation test. However, it is important to note that close and regular sodium monitoring every 30 min during the hypertonic saline test is a prerequisite, which is not possible in all hospitals. Furthermore, side effects are common. Therefore, a nonosmotic stimulation test would be advantageous. Arginine significantly stimulates copeptin and therefore is a novel, so far unknown stimulus of this peptide. Consequently, infusion of arginine with subsequent copeptin measurement was shown to be an even simpler and better tolerated test, but head to head comparison is still lacking.

Vasopressin actions in the kidney renin angiotensin system and its role in hypertension and renal disease

Vasopressin, also named antidiuretic hormone (ADH), arginine vasopressin (AVP) is the main hormone responsible for water maintenance in the body through the antidiuretic actions in the kidney. The posterior pituitary into the blood releases vasopressin formed in the hypothalamus. Hypothalamic osmotic neurons are responsible to initiate the cascade for AVP actions. The effects of AVP peptide includes activation of V2 receptors which stimulate the formation of cyclic AMP (cAMP) and phosphorylation of water channels aquaporin 2 (AQP2) in the collecting duct. AVP also has vasoconstrictor effects through V1a receptors in the vasculature, while V1b is found in the nervous system. V1a and b receptors increases intracellular Ca²⁺ while activation of V2 receptors of signaling pathways are related to cAMP-dependent phosphorylation in kidney collecting ducts acting in coordination to stimulate water and electrolyte homeostasis. AVP potentiate formation of intratubular angiotensin II (Ang II) through V2 receptors-dependent distal tubular renin formation, contributing to Na+ reabsorption. On the same way, Ang II receptors are able to potentiate the effects of V2-dependent stimulation of AQP2 abundance in the plasma membrane. The role of AVP in hypertension and renal disease has been demonstrated in pathological states with the involvement of V2 receptors in the progression of kidney damage in diabetes and also on the stimulation of intracellular pathways linked to the development of polycystic kidney.

Copeptin, myeloperoxidase and pro-adrenomedullin for acute coronary syndrome in patients with chronic kidney disease

Objectives:

Copeptin, myeloperoxidase and pro-adrenomedullin have emerged as potential biomarkers for diagnosis and prognosis of acute coronary syndrome (ACS). However, their applicability in patients with chronic kidney disease (CKD) remains unknown as these patients were excluded from previous studies. Our objective was to determine the superior novel cardiac marker to predict 30-day and six-month adverse cardiac events (ACEs) defined as cardiac-related death, myocardial infarction and ventricular fibrillation.

Methods:

A prospective observational study was carried out. Patients were included if they presented to the emergency department with symptoms suggestive of ACS and had CKD as defined as a serum creatinine of more than 130 µmol/l. Copeptin, myeloperoxidase and pro-adrenomedulin assays were performed. Occurrence of ACE was traced from review of the patients’ case records and the registry of deaths.

Results:

A total of 724 patients were recruited: 60.6% were male and 68.6% were Chinese. The median age was 67 years. Among those recruited, 88.3% had CKD stages 4 and 5, with 33.5% on dialysis. The rates of ACE at 30 days and six months were 15.1% and 21.7%, respectively. All readings of the three biomarkers were not significantly different in patients with ACE compared with those without both at 30 days and six months. The areas under the curve for copeptin, myeloperoxidase and pro-adrenomedullin were 0.53, 0.50 and 0.45, respectively ( p > 0.05).

Conclusions:

The poor performance of the biomarkers may be attributable to lack of specificity for ACS, as elevated levels could be from other causes in CKD patients. Routine testing cannot be recommended.

Vasopressin and Copeptin in health and disease

Arginine Vasopressin (AVP) and copeptin derive from the same precursor molecule. Due to the equimolar secretion, copeptin responds as rapidly as AVP to osmotic, hemodynamic and unspecific stress-related stimuli and both peptides show a very strong correlation. The physiological functions of AVP are homeostasis of fluid balance, vascular tonus and regulation of the endocrine stress response. In contrast, the exact function of copeptin remains unknown. Since copeptin, in contrast to AVP, can easily be measured with a sandwich immunoassay, its main function so far that it indirectly indicates the amount of AVP in the circulation. Copeptin has emerged as a useful measure in different diseases. On one hand, through its characteristics as a marker of stress, it provides a unique measure of the individual stress burden. As such, it is a prognostic marker in different acute diseases such as ischemic stroke or myocardial infarction. On the other side, it has emerged as a promising marker in the diagnosis of AVP-dependent fluid disorders. Copeptin reliably differentiates various entities of the polyuria polydipsia syndrome; baseline levels >20 pmol/L without prior fluid deprivation identify patients with nephrogenic diabetes insipidus, whereas levels measured upon osmotic stimulation with hypertonic saline or upon non-osmotic stimulation with arginine differentiate primary polydipsia from central diabetes insipidus. In patients with hyponatremia, low levels of copeptin together with low urine osmolality identify patients with primary polydipsia, but copeptin levels overlap in all other causes of hyponatremia, limiting its diagnostic use in hyponatremia. Copeptin has also been put forward as predictive marker for autosomal dominant polycystic kidney disease and for diabetes mellitus, but more studies are needed to confirm these findings.

Association of Serum Copeptin Levels with Patency of Infarct-Related Arteries in Patients with ST-Segment Elevation Myocardial Infarction

Background

Copeptin is widely used as a predictor of an adverse prognosis in many clinical conditions. Reduced antegrade coronary flow in an infarct-related artery (IRA) is associated with adverse clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). The aim of this study was to investigate whether copeptin level on admission was associated with IRA patency in STEMI patients.

Methods

A total of 88 patients were enrolled into the study and divided into two groups according to TIMI flow grade in the IRA before primary percutaneous coronary intervention.

Results

White blood cell count (p = 0.015), neutrophils (p = 0.047), N-terminal pro-brain natriuretic peptide (NTproBNP) (p < 0.001), copeptin (p < 0.001) and peak troponin I (p = 0.001) were significantly higher in the occluded IRA group with a significantly lower serum sodium level (p < 0.001). Age- and gender-adjusted multivariate analysis revealed that copeptin (OR = 1.970; p = 0.001), peak troponin I (1.055; p = 0.005) and NTproBNP (OR = 1.003; p = 0.010) were independent predictors of an occluded IRA. A copeptin cut-off value of > 6.8 ng/mL was found to predict an occluded IRA with a sensitivity of 80% and specificity of 100% (area under the curve: 0.917; p < 0.001). Performance ranking of the biomarkers that could predict an occluded IRA showed copeptin > peak troponin I = NTproBNP.

Conclusions

Copeptin levels were higher in the patients with an occluded IRA and STEMI. Higher levels of copeptin predicted an occluded IRA in the patients with STEMI who were admitted to the emergency department during the first three hours of chest pain.

Copeptin and its role in the diagnosis of diabetes insipidus and the syndrome of inappropriate antidiuresis

Copeptin is secreted in an equimolar amount to arginine vasopressin (AVP) but can easily be measured in plasma or serum with a sandwich immunoassay. The main stimuli for copeptin are similar to AVP, that is an increase in osmolality and a decrease in arterial blood volume and pressure. A high correlation between copeptin and AVP has been shown. Accordingly, copeptin mirrors the amount of AVP in the circulation. Copeptin has, therefore, been evaluated as diagnostic biomarker in vasopressin-dependent disorders of body fluid homeostasis. Disorders of body fluid homeostasis are common and can be divided into hyper- and hypoosmolar circumstances: the classical hyperosmolar disorder is diabetes insipidus, while the most common hypoosmolar disorder is the syndrome of inappropriate antidiuresis (SIAD). Copeptin measurement has led to a "revival" of the direct test in the differential diagnosis of diabetes insipidus. Baseline copeptin levels, without prior thirsting, unequivocally identify patients with nephrogenic diabetes insipidus. In contrast, for the difficult differentiation between central diabetes insipidus and primary polydipsia, a stimulated copeptin level of 4.9 pmol/L upon hypertonic saline infusion differentiates these two entities with a high diagnostic accuracy and is clearly superior to the classical water deprivation test. On the contrary, in the SIAD, copeptin measurement is of only little diagnostic value. Copeptin levels widely overlap in patients with hyponatraemia and emphasize the heterogeneity of the disease. Additionally, a variety of factors lead to unspecific copeptin elevations in the acute setting further complicating its interpretation. The broad use of copeptin as diagnostic marker in hyponatraemia and specifically to detect cancer-related disease in SIADH patients can, therefore, not be recommended.

EJE AWARD 2019: New diagnostic approaches for patients with polyuria polydipsia syndrome

Diabetes insipidus (DI), be it from central or nephrogenic origin, must be differentiated from secondary forms of hypotonic polyuria such as primary polydipsia. Differentiation is crucial since wrong treatment can have deleterious consequences. Since decades, the gold standard for differentiation has been the water deprivation test, which has limitations leading to an overall unsatisfying diagnostic accuracy. Furthermore, it is cumbersome for patients with a long test duration. Clinical signs and symptoms and MRI characteristics overlap between patients with DI and primary polydipsia. The direct test including vasopressin (AVP) measurement upon osmotic stimulation was meant to overcome these limitations, but failed to enter clinical practice mainly due to technical constraints of the AVP assay. Copeptin is secreted in equimolar amount to AVP but can easily be measured with a sandwich immunoassay. A high correlation between copeptin and AVP has been shown. Accordingly, copeptin mirrors the amount of AVP in the circulation and has led to a 'revival' of the direct test in the differential diagnosis of DI. We have shown that a baseline copeptin, without prior thirsting, unequivocally identifies patients with nephrogenic DI. In contrast, for the differentiation between central DI and primary polydipsia, a stimulated copeptin level of 4.9 pmol/L upon hypertonic saline infusion differentiates these two entities with a high diagnostic accuracy and is superior to the water deprivation test. Close sodium monitoring during the test is a prerequisite. Further new test methods are currently evaluated and might provide an even simpler way of differential diagnosis in the future.

Higher plasma levels of CT-proAVP are linked to less anxiety in men but not women with cardiovascular risk factors: Results from the observational Diast-CHF study

AIM

Using data from the multicenter, observational Diast-CHF (Diagnostic Trial on Prevalence and Clinical Course of Diastolic Dysfunction and Heart Failure) study, this post-hoc analysis aimed at assessing the association between serum concentrations of C-terminal pro-arginine vasopressin (CT-proAVP) and anxiety in patients with cardiovascular risk factors.

BACKGROUND

Animal studies have demonstrated that centrally released AVP is involved in the development of anxiety-like behaviors, however, it is unknown whether, also in humans, CT-proAVP used as a proxy for the co-secreted AVP is associated with self-reported anxiety.

METHODS

In 1463 study participants with cardiovascular risk factors (mean age 66.7 ± 8.1 years, 51.3% males, mean left ventricular ejection fraction 59.8 ± 8.3%), serum concentrations of CT-proAVP were measured by means of an ELISA assay, and anxiety was assessed using the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Data showed that there was a significant and inverse correlation between HADS anxiety and CT-proAVP (rho = -0.074; p = 0.005). Serum CT-proAVP and the HADS anxiety differed between the two sexes: men displayed lower anxiety (4.7 ± 3.5 versus 5.5 ± 3.7) and had higher CT-proAVP levels (5.8 pmol/L, interquartile range 3.5-9.9 pmol/L versus 3.0 pmol/L, interquartile range 2.0-4.7) than women (both, p < 0.001). Using univariate ANOVA adjusted for age, body-mass index, estimated glomerular filtration rate, left ventricular ejection fraction, 6-minute walking distance, SF-36 physical functioning, and the natriuretic peptides NT-proBNP and MR-proANP, the interaction term sex*CT-proAVP was significantly associated with anxiety (p = 0.006). Further analysis showed that CT-proAVP was inversely related to anxiety only in men (B = -0.991; 95%CI = -1.650 to -0.331; p = 0.003), but not in women (p = 0.335).

CONCLUSION

In male study participants with cardiovascular risk factors, serum concentrations of CT-proAVP showed an inverse association with anxiety, which was independent from the severity of physical impairment.

Serum Copeptin Levels Predict Clinical Outcomes After Successful Percutaneous Coronary Intervention in Patients With Acute Myocardial Infarction

BACKGROUND

Serum copeptin has been demonstrated to be useful in early risk stratification and prognostication of patients with acute myocardial infarction (AMI). However, the prognostic value of copeptin after percutaneous coronary intervention (PCI) for clinical outcomes remains uncertain. We investigated the prognostic role of serum copeptin levels immediately after successful PCI as a prognostic marker for major adverse cardiac events (MACE; comprising death, repeat PCI, recurrent MI, or coronary artery bypass grafting) in patients with AMI.

METHODS

A retrospective study was performed in 149 patients with AMI who successfully received PCI. Serum copeptin levels were analyzed in blood samples collected immediately after PCI. The association between copeptin levels and MACE during the follow-up period was evaluated.

RESULTS

MACE occurred in 34 (22.8%) patients during a median follow-up of 30.1 months. MACE patients had higher copeptin levels than non-MACE patients did. Multiple logistic regression analysis showed that the increase in serum copeptin levels was associated with increased MACE incidence (odds ratio=1.6, P=0.005).

CONCLUSIONS

A high level of serum copeptin measured immediately after PCI was associated with MACE in patients with AMI during long-term follow-up. Serum copeptin levels can serve as a prognostic marker in patients with AMI after successful PCI.

Association between Serum Copeptin and Stroke in Rural Areas of Northern China: A Matched Case-Control Study

Background

Copeptin has been implicated as an effective prognostic biomarker of stroke outcome; however, few studies have investigated whether copeptin could be used as an etiological factor for stroke or not. The aim of our study was to evaluate the association of serum copeptin with stroke.

Methods

In total, 238 participants including 119 cases (87 ischemic stroke and 32 hemorrhagic stroke) and 119 controls were included in this 1 : 1 matched case-control study. Conditional multivariate logistic regression was conducted to assess the Odds Ratios (ORs) and 95% confidence intervals (CI); restricted cubic spline in logistic regression model was used to evaluate the dose-response association between serum copeptin and total stroke, ischemic stroke, and hemorrhagic stroke.

Results

The median serum copeptin was 20.90 pmol/L, 20.90 pmol/L, 6.53 pmol/L, and 8.42 pmol/L for total stroke, ischemic stroke, hemorrhagic stroke, and healthy subjects, respectively. The corresponding ORs (95% CIs) for the highest compared with the lowest quartile were 1.23 (0.62–2.44) for total stroke, 4.01 (1.47–10.96) for ischemic stroke, and 0.13 (0.22–0.69) for hemorrhagic stroke. No nonlinear dose-response relationship was found between serum copeptin and total stroke (P_nonlinear = 0.278), ischemic stroke (P_nonlinear = 0.362), and hemorrhagic stroke (P_nonlinear = 0.314). Compared with the reference copeptin level, a significantly increasing trend was found between serum copeptin and ischemic stroke (P_overall = 0.002), and a decreasing trend was found between serum copeptin and hemorrhagic stroke (P_overall = 0.007).

Conclusions

Elevated serum copeptin levels were positively associated with ischemic stroke and adversely associated with hemorrhagic stroke. Additional prospective studies with larger sample size are needed to confirm the present findings.

Polyuria-polydipsia syndrome: a diagnostic challenge

The main determinants for the maintenance of water homeostasis are the hormone arginine vasopressin (AVP) and thirst. Disturbances in these regulatory mechanisms can lead to polyuria-polydipsia syndrome, which comprises of three different conditions: central diabetes insipidus (DI) due to insufficient secretion of AVP, nephrogenic DI caused by renal insensitivity to AVP action and primary polydipsia due to excessive fluid intake and consequent physiological suppression of AVP. It is crucial to determine the exact diagnosis because treatment strategies vary substantially. To differentiate between the causes of the polyuria-polydipsia syndrome, a water deprivation test combined with desmopressin administration is the diagnostic 'gold standard'. Thereby, AVP activity is indirectly evaluated through the measurement of urine osmolality after prolonged dehydration. However, this test has several limitations and may fail to distinguish precisely between patients with primary polydipsia and mild forms of central and nephrogenic DI. The direct measurement of AVP during the water deprivation test, which was reported in the 1980s, has not been widely adopted due to availability, assay issues and diagnostic performance. Recently, copeptin, the c-terminal portion of the larger precursor peptide of AVP, has been evaluated in the setting of polyuria-polydipsia syndrome and appears to be a useful candidate biomarker for the differential diagnosis. A standardised method for the water deprivation test is presented as part of a joint initiative of the Endocrine Society of Australia, the Australasian Association of Clinical Biochemists and the Royal College of Pathologists of Australasia to harmonise dynamic endocrine tests across Australia.

Cortisol Outperforms Novel Cardiovascular, Inflammatory, and Neurohumoral Biomarkers in the Prediction of Outcome in Acute Pancreatitis

OBJECTIVES

The aims of this study were to assess whether copeptin, pro-atrial natriuretic peptide, proadrenomedullin, and cortisol are associated with disease severity in patients with acute pancreatitis (AP) and to compare their ability in predicting organ failure or death.

METHODS

From April 2011 to January 2015, 142 patients with AP were included in this prospective single-center study and observed for 4 days. Disease severity was rated by the Atlanta 1992 and 2012 criteria and organ failure by the modified Marshall score. The aforementioned laboratory markers, C-reactive protein, and procalcitonin were measured.

RESULTS

Patients with moderate to severe AP showed significantly higher plasma concentrations of all biomarkers than did those with mild AP. Overall, 30 organ failures or deaths occurred. All biomarkers except cortisol had only modest discriminatory ability, with areas under the receiver operating characteristic curve (AUCs) between 0.44 and 0.66. Cortisol showed an AUC of 0.78 compared with the Acute Physiology and Chronic Health Evaluation II score with an AUC of 0.75.

CONCLUSIONS

Cortisol was the best predictor of organ failure or death. All biomarkers were associated with disease severity to a similar degree as C-reactive protein, the criterion-standard marker in AP. Further studies are warranted to define their clinical role.

Novel Risk Stratification Assays for Acute Coronary Syndrome

PURPOSE OF REVIEW

Since identification of aspartate aminotransferase as the first cardiac biomarker in the 1950s, there have been a number of new markers used for myocardial damage detection over the decades. There have also been several generations of troponin assays, each with progressively increasing sensitivity for troponin detection. Accordingly, the "standard of care" for myocardial damage detection continues to change. The purpose of this paper is to review the clinical utility, biological mechanisms, and predictive value of these various biomarkers in contemporary clinical studies.

RECENT FINDINGS

As of this writing, a fifth "next" generation troponin assay has now been cleared by the US Food and Drug Administration for clinical use in the USA for subjects presenting with suspected acute coronary syndromes. Use of these high-sensitivity assays has allowed for earlier detection of myocardial damage as well as greater negative predictive value for infarction after only one or two serial measurements. Recent algorithms utilizing these assays have allowed for more rapid rule-out of myocardial infarction in emergency department settings. In this review, we discuss novel assays available for the risk assessment of subjects presenting with chest pain, including both the "next generation" cardiac troponin assays as well as other novel biomarkers. We review the biological mechanisms for these markers, and explore the positive and negative predictive value of the assays in clinical studies, where reported. We also discuss the potential use of these new markers within the context of future clinical care in the modern era of higher sensitivity troponin testing. Finally, we discuss advances in new platforms (e.g., mass spectrometry) that historically have not been considered for rapid in vitro diagnostic capabilities, but that are taking a larger role in clinical diagnostics, and whose prognostic value and power promise to usher in new markers with potential for future clinical utility in acute coronary syndrome.

Predictive value of copeptin as a severity marker of community-acquired pneumonia

BACKGROUND

Pneumonia is the leading cause of death in children. Few studies have explored the predictive value of copeptin in pediatric pneumonia.

AIM

This study aimed to assess the role of copeptin as a marker of severity of community-acquired pneumonia (CAP).

METHODS

This prospective case-control study was carried out at Minia University Children's Hospital in Minia (Egypt) from January to December 2016. Eighty children aged from 2 months to 42 months were enrolled in this study and were classified into group 1 (40 children with clinical, laboratory and radiological evidence of pneumonia) and group 2 (40 apparently healthy control). Serum copeptin level was assayed for all enrolled children.

RESULTS

Mean serum copeptin level was significantly higher in pneumonic patients (985.7±619) pg/ml compared to controls (519±308.2) pg/ml (p<0.001). Serum copeptin was significantly elevated in survivors of pneumonia more than non-survivors (p=0.001). Also, copeptin was significantly higher in the group of non-survivors (1811.8±327.1) compared to 745.4±472.5 for survivors (p=0.01). There was a significant positive correlation between serum copeptin levels and the degree of respiratory distress (p=0.02).

CONCLUSION

Copeptin seems a reliable and available predictor marker for assessing the severity and prognosis of pediatric community acquired pneumonia.