Predictors of delayed first voiding in newborn

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.

AVPR1A distribution in the whole C57BL/6J mouse neonate

The neuropeptide arginine vasopressin (AVP) plays significant roles in maintaining homeostasis and regulating social behavior. In vaginally delivered neonates, a surge of AVP is released into the bloodstream at levels exceeding release during life-threatening conditions such as hemorrhagic shock. It is currently unknown where the potential sites of action are in the neonate for these robust levels of circulating AVP at birth. The purpose of this study is to identify the location of AVP receptor 1a (AVPR1A) sites as potential peripheral targets of AVP in the neonatal mouse. RT-qPCR analysis of a sampling of tissues from the head demonstrated the presence of Avpr1a mRNA, suggesting local peripheral translation. Using competitive autoradiography in wildtype (WT) and AVPR1A knockout (KO) postnatal day 0 (P0) male and female mice on a C57BL/6J background, specific AVPR1A ligand binding was observed in the neonatal mouse periphery in sensory tissues of the head (eyes, ears, various oronasal regions), bone, spinal cord, adrenal cortex, and the uro-anogenital region in the neonatal AVPR1A WT mouse, as it was significantly reduced or absent in the control samples (AVPR1A KO and competition). AVPR1A throughout the neonatal periphery suggest roles for AVP in modulating peripheral physiology and development of the neonate.

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.

Decreased free water clearance is associated with worse respiratory outcomes in premature infants

OBJECTIVE

The goal was to elucidate predictors of decreased free water clearance (DFWC) in very low birth weight (VLBW) infants. We hypothesized that DFWC and fluid retention are linked to the severity of pulmonary problems and prolonged respiratory support, especially to nCPAP treatment.

METHODS

The investigation was carried out at Tampere University Hospital between 2001 and 2006. The study population comprised 74 VLBW infants born at 29.21 (24.57-34.14) weeks of gestation. Median birth weight was 1175 (575-1490) grams. We measured plasma and urine osmolality and 24-hour urine volume to calculate free water clearance (FWC) for each infant. If FWC was less than 30 ml/kg/day the infant was classified as having DFWC.

RESULTS

There were 38 (51.4%) infants with DFWC in the study population. The median duration of the observed DFT period was 14 (4-44) days. The gestational age at birth was lower for DFWC infants compared to infants with normal FWC (NFWC), 28.29 (24.57-32.86) vs. 30.00 (25.57-34.14) weeks (p = 0.001). DFWC infants also needed longer ventilator treatment, 2 (0-23) vs. 0.50 (0-23) days (p = 0.046), nCPAP treatment 30 (0-100) vs. 3 (0-41) days (p<0.0001) and longer oxygen supplementation 47 (0-163) vs. 22 (0-74) days (p = 0.011) than NFWC infants. All values presented here are medians with ranges.

CONCLUSIONS

DFWC appears to be frequently connected with exacerbation and prolongation of pulmonary problems in VLBW infants. Cautious fluid administration seems to be indicated in VLBW infants with prolonged respiratory problems and DFWC.