Relationship between plasma copeptin levels and complications of community-acquired pneumonia in preschool children

Copeptin as a diagnostic and prognostic biomarker in pediatric diseases

Arginine vasopressin (AVP) plays a main role in maintaining the homeostasis of fluid balance and vascular tone and in regulating the endocrine stress response in response to osmotic, hemodynamic and stress stimuli. However, the difficulty in measuring AVP limits its clinical application. Copeptin, the C-terminal part of the AVP precursor, is released in an equimolar concentration mode with AVP from the pituitary but is more stable and simple to measure. Therefore, copeptin has emerged as a promising surrogate marker of AVP with excellent potential for the diagnosis, differentiation and prognosis of various diseases in recent decades. However, its application requires further validation, especially in the pediatric population. This review focuses on the clinical value of copeptin in different pediatric diseases and the prospects for its application as a potential biomarker.

Copeptin levels in hospitalized infants and children with suspected vasopressin-dependent disorders: a case series

OBJECTIVES

There have been recent advances assessing copeptin levels in adults with suspected disorders of vasopressin release. Very limited data exits on copeptin levels in children and infants, especially in a critically-ill hospitalized population where hyper- and hypo-natremia are very common. Our objective is to describe the institutional experience assessing copeptin levels in hospitalized infants and children with hyper- or hypo-natremia.

METHODS

We performed a single-center retrospective case series of all infants, children, and adolescents who had an ultrasensitive plasma copeptin level obtained between 2019-2021.

RESULTS

A total of 29 critically ill patients (6 infants) were identified with 38 % of patients having copeptin levels after neurosurgical procedures for tumors or trauma. Approximately 13/17 children with hypernatremia had CDI to diagnose CDI, A copeptin level ≤ 4.9 pmol/L resulted in an 88 % sensitivity (95 % CI 47-99 %), and 66 % specificity (95 % CI 30-93 %). Amongst those with hyponatremia levels were more variable, 8/12 children had SIAD with copeptin levels ranging 4.7-72.6 pmol/L.

CONCLUSIONS

While difficult to conclude due to multiple limitations, this case series highlights that typical copeptin cutoffs used to diagnose DI in adults in an ambulatory setting may also translate to a critically-ill pediatric population. Large prospective studies are needed to confirm this observation. In addition, postoperative copeptin levels could potentially be utilized as an additional marker to predict permanent from transient DI, but much larger studies are needed. Further work is needed to establish normative copeptin levels in infants and patients with SIAD.

Arginine-stimulated copeptin in children and adolescents

OBJECTIVE

Copeptin is secreted in isomolar amounts along with arginine vasopressin peptide (AVP) from the neurohypophysis. Its stability makes it a perfect candidate for the endocrine approach in the diagnosis of AVP deficiency (AVPD; cranial diabetes insipidus; CDI). However, pediatric reference values are lacking.

DESIGN AND PATIENTS

This is a monocentric retrospective analysis of donated residual serum samples from 72 children and adolescents who underwent arginine or growth hormone-releasing hormone-arginine stimulation to test GH secretory capacity from 2018 to 2022.

MEASUREMENTS

Copeptin was measured in baseline, 30-, and 60-min samples by BRAHMS Copeptin proAVP Kryptor immunofluorescence assay.

RESULTS

Of the 72 patients, 4 suffered from complete AVPD (CDI). The baseline level of copeptin in the 68 non-AVPD (non-CDI) patients was highly variable (range: 1.3-44.4 pmol/L). The increase after arginine was moderate (30 min range: 1.6-40.4 pmol/L). The median baseline and peak copeptin levels were 5.6 and 8.0 pmol/L, respectively. The 2.5th percentile of the baseline and peak values of copeptin were 2.1 and 3.3 pmol/L, respectively. The increase and peak value of copeptin were inversely related to age (R = -.405; p = .011, and R = -.335; p = .0072, respectively) but not to gender, body mass index (standard deviation score) or GH secretion. In the four patients with AVPD (CDI), baseline or stimulated copeptin was below the 2.5th percentile of non-AVPD (non-CDI) patients.

CONCLUSIONS

Stimulated copeptin is a promising parameter for the differential diagnosis of polyuria-polydipsia syndrome. However, the low copeptin increase after arginine and the high limit of quantification of the assay are problematic for use in paediatrics.

Copeptin Release in Arterial Hypotension and Its Association with Severity of Disease in Critically Ill Children

Low copeptin levels may indicate inadequate arginine-vasopressin release promoting arterial hypotension, whereas high copeptin concentrations may reflect disease severity. This single-center prospective non-randomized clinical trial analyzed the course of blood copeptin in critically ill normo- and hypotensive children and its association with disease severity. In 164 patients (median age 0.5 years (interquartile range 0.1, 2.9)), the mean copeptin concentration at baseline was 43.5 pmol/L. Though not significantly different after 61 h (primary outcome, mean individual change: −12%, p = 0.36, paired t-test), we detected 1.47-fold higher copeptin concentrations during arterial hypotension when compared to normotension (mixed-effect ANOVA, p = 0.01). In total, 8 out of 34 patients (23.5%) with low copeptin concentrations <10 pmol/L were hypotensive. Copeptin was highest in the adjusted mixed-effect regression analysis within the first day (+20% at 14 h) and decreased significantly at 108 h (−27%) compared to baseline (p = 0.002). Moreover, we found a significant association with vasopressor-inotrope treatment intensity, infancy (1−12 months) and cardiopulmonary bypass (all p ≤ 0.001). In conclusion, high copeptin values were associated with arterial hypotension and severity of disease in critically ill children. This study does not support the hypothesis that low copeptin values might be indicative of arginine-vasopressin deficiency.

The kinetic profiles of copeptin and mid regional proadrenomedullin (MR-proADM) in pediatric lower respiratory tract infections

Background

Kinetics of copeptin and mid regional proadrenomedullin (MR-proADM) during febrile pediatric lower respiratory tract infections (LRTI) are unknown. We aimed to analyze kinetic profiles of copeptin and MR-proADM and the impact of clinical and laboratory factors on those biomarkers.

Methods

This is a retrospective post-hoc analysis of a randomized controlled trial, evaluating procalcitonin guidance for antibiotic treatment of LRTI (ProPAED-study). In 175 pediatric patients presenting to the emergency department plasma copeptin and MR-proADM concentrations were determined on day 1, 3, and 5. Their association with clinical characteristics and other inflammatory biomarkers were tested by non-linear mixed effect modelling.

Results

Median copeptin and MR-proADM values were elevated on day 1 and decreased during on day 3 and 5 (-26%; -34%, respectively). The initial concentrations of MR-proADM at inclusion were higher in patients receiving antibiotics intravenously compared to oral administration (difference 0.62 pmol/L, 95%CI 0.44;1.42, p<0.001). Intensive care unit (ICU) admission was associated with a daily increase of MR-proADM (increase/day 1.03 pmol/L, 95%CI 0.43;1.50, p<0.001). Positive blood culture in patients with antibiotic treatment and negative results on nasopharyngeal aspirates, or negative blood culture were associated with a decreasing MR-proADM (decrease/day -0.85 pmol/L, 95%CI -0.45;-1.44), p<0.001).

Conclusion

Elevated MR-proADM and increases thereof were associated with ICU admission suggesting the potential as a prognostic factor for severe pediatric LRTI. MR-proADM might only bear limited value for decision making on stopping antibiotics due to its slow decrease. Copeptin had no added value in our setting.

Copeptin assays in children for the differential diagnosis of polyuria-polydipsia syndrome and reference levels in hospitalized children

OBJECTIVES

Polyuria-polydipsia syndrome (PPS) is a common presentation in children but the differential diagnosis rests on burdensome water deprivation tests. The aims of this study were to determine a copeptin threshold to distinguish patients with central diabetes insipidus from those with primary polydipsia and to estimate the normal range of copeptin concentrations in children.

DESIGN

Single-centre retrospective descriptive study.

PATIENTS

Two hundred and seventy-eight children aged 2 months to 18 years who consulted for PPS (N = 40) or other reasons (control group, N = 238) at La Timone University Hospital in Marseille, France, between April 2015 and September 2019 and had a copeptin assay.

MEASUREMENTS

Ultrasensitive copeptin assays on blood samples.

RESULTS

Among the children with PPS, the mean copeptin concentrations were 1.72, 55.2 and 15.7 pmol/l in those with central diabetes insipidus (N = 21), nephrogenic diabetes insipidus (N = 3), and primary polydipsia (N = 16), respectively. Copeptin levels lower than 3.53 pmol/l were diagnostic of central diabetes insipidus with 100% sensitivity and 87.4% specificity (p < .001). The 5th-95th copeptin percentile range in the control group was 2.53-21.03 pmol/L. Copeptin levels were significantly higher in boys than in girls but there was no association with age, pubertal stage, body mass index, or the reason for consulting.

CONCLUSIONS

Our results indicate copeptin assays may be valuable in the differential diagnosis of PPS in children. Larger prospective studies are required to establish their accuracy in everyday clinical practice.

Vasopressin-Dependent Disorders: What Is New in Children?

Arginine vasopressin (AVP)-mediated osmoregulatory disorders, such as diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are common in the differential diagnosis for children with hypo- and hypernatremia and require timely recognition and treatment. DI is caused by a failure to concentrate urine secondary to impaired production of or response to AVP, resulting in hypernatremia. Newer methods of diagnosing DI include measuring copeptin levels; copeptin is AVP's chaperone protein and serves as a surrogate biomarker of AVP secretion. Intraoperative copeptin levels may also help predict the risk for developing DI after neurosurgical procedures. Copeptin levels hold diagnostic promise in other pediatric conditions, too. Recently, expanded genotype and phenotype correlations in inherited DI disorders have been described and may better predict the clinical course in affected children and infants. Similarly, newer formulations of synthetic AVP may improve pediatric DI treatment. In contrast to DI, SIADH, characterized by inappropriate AVP secretion, commonly leads to severe hyponatremia. Contemporary methods aid clinicians in distinguishing SIADH from other hyponatremic conditions, particularly cerebral salt wasting. Further research on the efficacy of therapies for pediatric SIADH is needed, although some adult treatments hold promise for pediatrics. Lastly, expansion of home point-of-care sodium testing may transform management of SIADH and DI in children. In this article, we review recent developments in the understanding of pathophysiology, diagnostic workup, and treatment of better outcomes and quality of life for children with these challenging disorders.

Efficacy of copeptin in distinguishing COVID-19 pneumonia from community-acquired pneumonia

The clinical symptoms of community‐acquired pneumonia (CAP) and coronavirus disease 2019 (COVID‐19)‐associated pneumonia are similar. Effective predictive markers are needed to differentiate COVID‐19 pneumonia from CAP in the current pandemic conditions. Copeptin, a 39‐aminoacid glycopeptide, is a C‐terminal part of the precursor pre‐provasopressin (pre‐proAVP). The activation of the AVP system stimulates copeptin secretion in equimolar amounts with AVP. This study aims to determine serum copeptin levels in patients with CAP and COVID‐19 pneumonia and to analyze the power of copeptin in predicting COVID‐19 pneumonia. The study consists of 98 patients with COVID‐19 and 44 patients with CAP. The basic demographic and clinical data of all patients were recorded, and blood samples were collected. The receiver operating characteristic (ROC) curve was generated and the area under the ROC curve (AUC) was measured to evaluate the discriminative ability. Serum copeptin levels were significantly higher in COVID‐19 patients compared to CAP patients (10.2 ± 4.4 ng/ml and 7.1 ± 3.1 ng/ml; p < .001). Serum copeptin levels were positively correlated with leukocyte, neutrophil, and platelet count (r = −.21, p = .012; r = −.21, p = .013; r = −.20, p = .018; respectively). The multivariable logistic regression analysis revealed that increased copeptin (odds ratio [OR] = 1.183, 95% confidence interval [CI], 1.033–1.354; p = .015) and CK‐MB (OR = 1.052, 95% CI, 1.013–1.092; p = .008) levels and decreased leukocyte count (OR = 0.829, 95% CI, 0.730–0.940; p = .004) were independent predictors of COVID‐19 pneumonia. A cut‐off value of 6.83 ng/ml for copeptin predicted COVID‐19 with a sensitivity of 78% and a specificity of 73% (AUC: 0.764% 95 Cl: 0.671–0.856, p < .001). Copeptin could be a promising and useful biomarker to be used to distinguish COVID‐19 patients from CAP patients.

Distribution of plasma copeptin levels and influence of obesity in children and adolescents

In recent years, a more stable AVP surrogate, called copeptin, has been used as an adjuvant diagnostic tool for dysnatremia in adults and appears to be promising even in the pediatric age. The aim of this study is to present the distribution of plasma copeptin in a large pediatric cohort and to observe the influence of fluid consumption and obesity on its values. A cohort of 128 children and adolescents was divided into two groups on the basis of nocturnal deprivation (group A) or free access to oral fluids in the 6-8 h before blood collection (group B). At all distribution percentiles, copeptin levels were higher (p < 0.0001) in group A, as were plasma sodium levels and osmolality (p = 0.02 and p = 0.008, respectively). The influence of BMI on copeptin levels was investigated by dividing the cohort into nonobese (group C) and obese children and adolescents (group D). Copeptin levels were higher in group D (p = 0.04).Conclusion: The measurement of copeptin could represent a useful tool for the diagnostic pathway of dysnatremic conditions, but its interpretation should take into consideration the state of hydration. Furthermore, it could also be a promising marker for obesity and metabolic syndrome, although this hypothesis needs further studies to be confirmed. What is Known: • Copeptin use as a diagnostic tool in AVP-related disorders, such as diabetes insipidus or syndrome of inappropriate secretion of antidiuretic hormone, is well established in adults • In pediatric age, few studies are available, but the preliminary data, including our previous study, seems to be promising. What is New: • In this study, we represent the distribution of copeptin levels in a pediatric cohort and show the significant influence of fluid ingestion on its plasma levels. • Also BMI seems to be a significant variable on copeptin levels and may be used as an obesity marker in pediatric age.

Evaluation of Copeptin during Pulmonary Exacerbation in Cystic Fibrosis

Copeptin was found to be a stable biomarker of inflammation and stress response in cardiac, renal, metabolic, and respiratory conditions such as pneumonia. The aim of this study was to investigate the copeptin levels in biological fluids (serum and sputum supernatant) of cystic fibrosis pediatric patients during pulmonary exacerbation and remission and to investigate the possible influence of copeptin levels on disease severity and quality of life. Copeptin serum concentrations were measured in 28 pediatric cystic fibrosis (CF) patients: 13 in stable condition and 15 during pulmonary exacerbation. In 10 CF patients, copeptin was also measured in the sputum. In all the patients, we assessed complete blood count, BMI, sputum culture, lung function, and chest imaging (with Brasfield score). The severity of symptoms was assessed using the Shwachman-Kulczycki (SK) score, and the quality of life was assessed with the Cystic Fibrosis Quality of Life Questionnaire-Revised (CFQ-R). Copeptin concentrations in serum and sputum supernatant was measured using an ELISA kit. Statistical analysis was done in Statistica v.12. Serum and sputum copeptin levels were higher in CF patients during pulmonary exacerbation than in a stable period, but the differences were not significant (p = 0.58 and p = 0.13, respectively). Copeptin did not correlate significantly with any clinical, laboratory, or spirometry markers of exacerbation. There was, however, a significant inverse correlation between the serum copeptin level and symptoms severity (r = ‐0.77, p = 0.008) and radiological changes (r = ‐0.5626, p = 0.036) during pulmonary exacerbation in pediatric CF patients. Copeptin also inversely correlated with the quality of life domains in CF patients: vitality and eating habits, mostly loss of appetite (p = 0.031 and p = 0.016, respectively). Copeptin may be useful to identify patients with a higher risk of deterioration to improve their outcomes.

Copeptin role in polyuria-polydipsia syndrome differential diagnosis and reference range in paediatric age

OBJECTIVE

Plasma arginine-vasopressin (AVP) analysis can help in the differential diagnosis of the polyuria-polydipsia syndrome (PPS), even if such investigation is hampered by technical difficulties, conversely to its surrogate copeptin. This study aims to enlarge the existing data on normal copeptin levels in childhood, to evaluate the correlation between copeptin, serum sodium and plasma and urine osmolality, and to assess the utility of the copeptin analysis in the diagnostic work-up of PPS in the paediatric age.

PATIENTS AND METHODS

Plasma copeptin levels were evaluated in 53 children without AVP disorders (control population), in 12 hypopituitaric children and in 15 patients with PPS after water deprivation test (WDT).

RESULTS

Mean basal copeptin levels were 5.2 ± 1.56 (range 2.4-8.6 pmol/L) in the control population, 2.61 ± 0.49 pmol/L in the hypopituitaric children with complete diabetes insipidus (CDI) (P = .04) and 6.21 ± 1.17 pmol/L in the hypopituitaric patients without DI (P = .02). After WDT, among 15 naïve polyuric/polydipsic children, copeptin values greater than 20 pmol/L allowed to identify nephrogenic diabetes insipidus (NDI), concentrations below 2.2 pmol/L complete central DI (CCDI) and between 5 and 20 pmol/L primary polydipsia (PP). Copeptin cut-off level of 3.5 pmol/L distinguished CDI from PP, with a sensitivity and specificity of 75% and 83.3%, respectively.

CONCLUSION

Copeptin evaluation holds promises as a diagnostic tool in paediatric PPS; its interpretation might be useful to promptly distinguish NDI, even avoiding the WDT need.

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.

Serum Copeptin Level as a Predictor of Outcome in Pneumonia

This cross-sectional study included 41 children (age 2 mo-12 y) with pneumonia and 40 healthy controls. Assay of serum copeptin was done using ELISA. Median serum copeptin levels were significantly higher (P=0.03) in children with pneumonia, and in those who died (P=0.04). We conclude that serum copeptin levels seem to be associated with poor outcome in pneumonia.

A Dormant Microbial Component in the Development of Preeclampsia

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

Copeptin as a serum biomarker of febrile seizures

Background and Objectives

Accurate diagnosis of febrile seizures in children presenting after paroxysmal episodes associated with fever, is hampered by the lack of objective postictal biomarkers. The aim of our study was to investigate whether FS are associated with increased levels of serum copeptin, a robust marker of arginine vasopressin secretion.

Methods

This was a prospective emergency-setting cross-sectional study of 161 children between six months and five years of age. Of these, 83 were diagnosed with febrile seizures, 69 had a febrile infection without seizures and nine had epileptic seizures not triggered by infection. Serum copeptin and prolactin levels were measured in addition to standard clinical, neurophysiological, and laboratory assessment. Clinical Trial Registration: NCT01884766.

Results

Circulating copeptin was significantly higher in children with febrile seizures (median [interquartile range] 18.9 pmol/L [8.5-36.6]) compared to febrile controls (5.6 pmol/L [4.1-9.4]; p <0.001), with no differences between febrile and epileptic seizures (21.4 pmol/L [16.1-46.6]; p = 0.728). In a multivariable regression model, seizures were the major determinant of serum copeptin (beta 0.509; p <0.001), independently of clinical and baseline laboratory indices. The area under the receiver operating curve for copeptin was 0.824 (95% CI 0.753-0.881), significantly higher compared to prolactin (0.667 [0.585-0.742]; p <0.001). The diagnostic accuracy of copeptin increased with decreasing time elapsed since the convulsive event (at 120 min: 0.879 [0.806-0.932] and at <60 min: 0.975 [0.913-0.997]).

Conclusions

Circulating copeptin has high diagnostic accuracy in febrile seizures and may be a useful adjunct for accurately diagnosing postictal states in the emergency setting.