Copeptin: a marker for stress reaction in fetuses with intrauterine growth restriction

Copeptin: Up-to-date diagnostic and prognostic role highlight

Arginine Vasopressin (AVP) is one of the key hormones in the human body. AVP is clinically important because it maintains body fluid balance and vascular tone. Unfortunately, AVP laboratory measurements are always difficult and with low accuracy. Copeptin, the C-terminal of the AVP precursor, is released in equal amounts with AVP, making it a sensitive marker of AVP release. Despite being a non-specific biomarker, copeptin earned a lot of attention as a novel biomarker due to easy and quick laboratory measurements. Recent studies have reported the critical role of copeptin as a clinical indicator, especially in the diagnosis and prognosis of many diseases. Besides, it was reported that the combination between copeptin and gold standard biomarkers improved the prognostic values of those biomarkers. In this review, the role of copeptin as a new predictive diagnostic and prognostic biomarker of various diseases is highlighted according to the most recent studies. In addition, the importance of using copeptin as a marker in different medical departments and the impact of this on improving healthcare service was discussed.

Copeptin Concentrations in Plasma of Healthy Neonates in Relation to Water–Electrolyte Homeostasis in the Early Adaptation Period

Copeptin (CTproAVP) is a stable by-product of arginine–vasopressin synthesis and reflects its secretion by the pituitary gland, considered as a potential new marker of dehydration. The objective of the study was to investigate CTproAVP measured after the first 48 h of postnatal life in relation to serum effective osmolality, urine osmolality, and vessels filling according to the following variables: delivery mode, postnatal weight loss, fluids administered intravenously to the mother, and fluids given orally to the neonate. A prospective observational study was conducted with 200 healthy term infants (53% male) enrolled. Serum CTproAVP concentrations were measured using the ELISA kit; haematocrit, urine osmolality, serum effective osmolality were assessed after 48 h of life. Sonographic measurements of inferior vena cava (IVC) and aorta (Ao) were performed and IVC/Ao ratios were calculated. No correlations were found between CTproAVP concentrations and both serum effective osmolality and urine osmolality. There was also no association between CTproAVP concentrations and vessel filling represented by IVC/Ao index at 48 h of life.

Copeptin and Stress

Vasopressin (AVP) and copeptin are released in equimolar amounts from the same precursor. Due to its molecular stability and countless advantages as compared with AVP, copeptin perfectly mirrors AVP presence and has progressively emerged as a reliable marker of vasopressinergic activation in response to osmotic and hemodynamic stimuli in clinical practice. Moreover, evidence highlighting the prognostic potential of copeptin in several acute diseases, where the activation of the AVP system is primarily linked to stress, as well as in psychologically stressful conditions, has progressively emerged. Furthermore, organic stressors induce a rise in copeptin levels which, although non-specific, is unrelated to plasma osmolality but proportional to their magnitude: suggesting disease severity, copeptin proved to be a reliable prognostic biomarker in acute conditions, such as sepsis, early post-surgical period, cardiovascular, cerebrovascular or pulmonary diseases, and even in critical settings. Evidence on this topic will be briefly discussed in this article.

Improving Neonatal and Maternal Outcome by Inducing Mild Labor before Elective Cesarean Section: The Lacarus Randomized Controlled Trial

BACKGROUND

Newborns delivered by elective cesarean section (CS) are at higher respiratory risk than those delivered vaginally or by CS proceeded by labor (secondary CS). The oxytocin challenge test (OCT) induces uterine contractions that trigger the release of fetal hormones regulating lung fluid clearance during transition from the uterine to an air-breathing environment.

OBJECTIVES

The aim is to summarize current evidence and outline the Lacarus trial protocol.

METHODS

Literature review informed the design of a randomized placebo-controlled multicenter trial of OCT preceding elective CS in 1,450 women with a singleton pregnancy due for CS at >35 weeks gestation, without preceding contractions, rupture of the membranes, or antenatal steroids. OCT comprises the infusion of oxytocin 5 IU/500 mL Ringer lactate at a rate of 12 mL/h, doubling every 10 min until inducing 5 uterine contractions per 15-min interval. The primary endpoint is the occurrence of neonatal respiratory morbidity within 24 h after birth. Secondary endpoints include biochemical and physiological parameters of fetal and maternal well-being, such as breastfeeding rate and fetal plasma copeptin concentrations.

CONCLUSION

This is the first trial to test the hypothesis that oxytocin-induced contractions before elective CS is a promising application of physiologic principles gleaned from natural birth to improve neonatal and maternal outcomes.

Non-invasive monitoring of stress biomarkers in the newborn period

The neonatal period is a highly sensitive time span during which stressful experiences may have an influence on later health outcomes. Medical procedures applied to newborn babies during hospitalization are stressors that trigger a physiological and psychological stress response. Stress response has been traditionally evaluated using scores based on behavioural signs such as facial expressions, limb movements, crying, etc., which are subjectively interpreted. Only few studies have employed measurable physiological signs to objectively evaluate the stress response to specific interventions. The aim of this review is to inform of recently developed biochemical methods that allow clinicians to evaluate the stress response to medical procedures performed in the neonatal period in biological samples non-invasively obtained. Stress biomarkers are based on the physiological stress response mediated by the hypophysis-pituitary-adrenal axis and the sympathetic-adreno-medullary systems. Cortisol is at present the most widely employed laboratory determination to measure stress levels. In recent years, sequentially determined salivary cortisol levels have allowed non-invasive monitoring of newborn infants under stressful conditions in the NICU.

Cardiovascular Biomarkers in Amniotic Fluid, Umbilical Arterial Blood, Umbilical Venous Blood, and Maternal Blood at Delivery, and Their Reference Values for Full-Term, Singleton, Cesarean Deliveries

Background: Several cardiovascular biomarkers have regulatory functions in perinatal physiology. Aim: This study aimed to analyze the feto-maternal distribution pattern of biomarkers in samples of amniotic fluid, umbilical arterial blood, umbilical venous blood, and maternal blood samples, and to establish reference values. Each linked sample set consisted of the combined samples obtained in an individual pregnancy. Study design: We performed a prospective, observational, cross-sectional, single-center study. Subjects: The sample cohort included 189 neonates who were born to 170 mothers. A total of 162/189 neonates were full term and 129/189 were delivered by elective cesarean section. Outcome measures: Midregional pro-adrenomedullin (MRproADM [nmol/L]), midregional pro-atrial natriuretic peptide (MRproANP [pmol/L]), brain natriuretic peptide (BNP [pg/mL]), N-terminal pro-brain natriuretic peptide (NTproBNP [pg/mL]), copeptin [pmol/L], and high-sensitive troponin I (hsTnI [pg/mL]) levels were measured. Results: In singleton, full-term, primary cesarean deliveries (n = 91), biomarker levels (median, [IQR]) at delivery were as follows. MRproADM levels in umbilical arterial blood/umbilical venous blood/amniotic fluid/maternal blood were 0.88 (0.20)/0.95 (0.18)/2.80 (1.18)/1.10 (0.54), respectively. MRproANP levels were 214.23 (91.38)/216.03 (86.15)/0.00 (3.82)/50.67 (26.81), respectively. BNP levels were 14.60 (25.18)/22.08 (18.91)/7.15 (6.01)/6.20 (18.23), respectively. NTproBNP levels were 765.48 (555.24)/816.45 (675.71)/72.03 (55.58)/44.40 (43.94), respectively. Copeptin levels were 46.17 (290.42)/5.54 (9.08)/9.97 (7.44)/4.61 (4.59), respectively. Levels of hsTnI were 6.20 (4.25)/5.60 (5.01)/0.45 (1.73)/2.50 (2.40), respectively. Conclusion: We determined reference values for biomarkers in term neonates delivered by primary cesarean section in amniotic fluid, umbilical arterial and venous blood, and maternal blood. Biomarkers in the fetal circulation appear to be of primary fetal origin, except for MRproADM.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.

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Zusammenfassung. Epidemiologische sowie tierexperimentelle Studien erbrachten den Nachweis, dass ein zu niedriges Geburtsgewicht ein Risikofaktor für kardiovaskuläre Erkrankungen im Erwachsenenalter darstellt. Die Diagnose einer intrauterinen Wachstumsretardierung (IUGR) erfolgt vorgeburtlich mittels Ultraschall. Bei einem Neugeborenen ist die Differenzierung zwischen einer Wachstumsretardierung und einem konstitutionell kleinem Kind schwierig. Hierfür, wie auch für die pathophysiologische Verbindung zwischen einer IUGR und einer späteren kardiovaskulären Erkrankung, ist die Erforschung der physiologischen, endokrinen und morphologischen Anpassungen des Föten an eine Mangelversorgung essenziell.

Cardiovascular biomarkers in paired maternal and umbilical cord blood samples at term and near term delivery

BACKGROUND

Cardiovascular biomarkers might help to identify fetuses or pregnancies at risk.

AIM

To examine the umbilical cord neonatal and maternal levels of cardiovascular biomarkers at the time of delivery, and to correlate maternal and fetal biomarker levels to each other, to gestational age and to delivery mode.

STUDY DESIGN

In a prospective, observational, cross-sectional, single-center study biomarkers were measured in paired maternal and umbilical venous cord blood samples.

SUBJECTS

The sample cohort included 66 sets of fetal and maternal blood samples (11 after multiple gestation, 53 after cesarean section, 17 after exposure to labor).

OUTCOME MEASURES

Midregional pro-adrenomedullin (MRproADM), midregional-pro atrial natriuretic peptide (MRproANP), brain natriuretic peptide (BNP), n-terminal-pro brain natriuretic peptide (NTproBNP), copeptin, and high sensitive troponin I (hsTnI) levels were measured.

RESULTS

Mean ± SEM for biomarker levels in umbilical venous/maternal blood were: MRproADM [nmol/L] 1.02 ± 0.04/1.24 ± 0.08, MRproANP [pmol/L] 215.53 ± 12.96/54.65 ± 3.41, BNP [pg/mL] 32.02 ± 3.37/19.76 ± 3.29, NTproBNP [pg/mL] 1228.94 ± 91.73/71.48 ± 8.65, copeptin [pmol/L] 103.42 ± 22.89/10.41 ± 1.71, and hsTnI [pg/mL] 13.54 ± 5.17/4.91 ± 2.37. Fetal MRproANP, NTproBNP, and BNP were inversely correlated with gestational age. Maternal and fetal MRproANP (r=0.472, p=0.002) and copeptin (r=0.572, p<0.001) levels were correlated, whereas there was no feto-maternal correlation for the other biomarkers. Fetal copeptin was elevated after exposure to labor.

CONCLUSIONS

Biomarker levels appear to be regulated independently in mother and fetus. Fetal biomarkers are influenced by gestational age and delivery mode. In this study on term and near term pregnancies without specific fetal pathology, correlation between paired maternal and fetal biomarker levels was weak or not demonstrable.

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.