Urine Biomarkers for the Assessment of Acute Kidney Injury in Neonates with Hypoxic Ischemic Encephalopathy Receiving Therapeutic Hypothermia

Acute Kidney Injury and Abnormalities on Brain Magnetic Resonance Imaging or Death in Infants with Hypoxic-Ischemic Encephalopathy: A Case-Control Study

OBJECTIVE

 This study aimed to analyze the association between acute kidney injury (AKI) and abnormalities on brain magnetic resonance imaging (MRI) or death in neonates treated with therapeutic hypothermia for hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

 This is a retrospective case-control analysis of 380 neonates born at ≥35 weeks' gestation treated with therapeutic hypothermia for HIE. Death or abnormal brain MRI using the basal ganglia watershed scoring system was compared between neonates with and without AKI.

RESULTS

 A total of 51 (13.4%) neonates had AKI. Infants with AKI had higher rates of the composite of death or abnormal brain MRI (74.5 vs. 38.3%; p < 0.001). Rate of death (21.6 vs. 5.5%; p < 0.001) and severe abnormalities on MRI or death (43.1 vs. 19.1%; p < 0.001) were also higher in neonates with AKI.

CONCLUSION

 AKI is strongly associated with abnormalities on brain MRI or death in neonates with HIE. Identification of AKI in this patient population may be helpful in guiding clinical management and predicting potential neurodevelopmental impairment.

KEY POINTS

· Neonates with HIE are at increased risk for AKI.. · AKI is associated with hypoxic-ischemic injury on brain MRI or death among neonates with HIE.. · Identification of AKI in infants with HIE may help predict neurodevelopmental impairment..

Use of urine neutrophil gelatinase-associated lipocalin for nephrotoxic medication acute kidney injury screening in neonates

BACKGROUND

Daily serum creatinine monitoring protocols for acute kidney injury (AKI) are invasive and may lead to surveillance resistance. We aimed to understand if use of urine neutrophil gelatinase-associated lipocalin (uNGAL) could increase high-risk nephrotoxic medication (NTMx) associated AKI screening adherence in neonates.

METHODS

Statistical process control methods prior to and post implementation were trended. The primary outcome, screening adherence, was defined as either daily serum creatinine or uNGAL assessment through 2 days post high-risk NTMx exposure.

RESULTS

1291 monitoring days from the pre-implementation era (4/2020-6/2021) were compared to1377 monitoring days from the post-era (6/2021-10/2022). AKI screening adherence increased (81 to 92%) following implementation of optional uNGAL screening. Urine NGAL accounted for 35% of screening obtained. Use of uNGAL resulted in a 40% reduction in blood sampling for serum creatinine.

CONCLUSIONS

Incorporation of uNGAL as a complementary screening tool to serum creatinine demonstrated sustained increased AKI surveillance in our Baby NINJA monitoring program.

Urine biomarkers of acute kidney injury and association with brain MRI abnormalities in neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

Determine whether urine biomarkers NGAL (neutrophil gelatinase-associated lipocalin), KIM-1 (kidney injury molecule 1) and IL-18 (interleukin-18) are associated with abnormal MRI findings in neonates with hypoxic-ischemic encephalopathy (HIE) who underwent therapeutic hypothermia (TH).

STUDY DESIGN

Secondary analysis of a multicenter, prospective study of neonates with HIE requiring TH. Urine biomarkers were obtained at 12 and 24 h of life (HOL). Brain MRI was scored per NICHD criteria. Association between biomarkers and MRI stage was determined.

RESULTS

In 57 neonates with HIE, only IL-18 at 24 HOL was significantly increased in neonates with MRI Stage 2B or greater, compared to Stage 2A or less (mean 398.7 vs. 182.9 pg/mL, p = 0.024.) A multivariate model including IL-18 at 24 HOL and 5-min Apgar performed best, with an AUC of 0.84 (SE = 0.07, p = 0.02).

CONCLUSIONS

Elevated urine IL-18 at 24 HOL was associated with more severe brain MRI abnormalities among neonates with HIE.

Potential Adjuncts to Therapeutic Hypothermia to Mitigate Multiorgan Injury in Perinatal Hypoxia-Ischemia

Over the last 2 decades, therapeutic hypothermia has become the standard of care to reduce morbidity and mortality in neonates affected by moderate-to-severe hypoxic-ischemic encephalopathy (HIE). There is a significant interest in improving the neurologic outcomes of neonatal HIE, ranging from adjunctive therapy to therapeutic hypothermia. Importantly, the pathophysiologic mechanisms underlying HIE also affect multiple other organs, contributing to high morbidity and mortality in this patient population. This review focuses on the adjunct therapies currently under investigation to mitigate the impact of hypoxic-ischemic injury on the brain, kidneys, liver, heart, and gastrointestinal system.

Gut microbiota and neonatal acute kidney injury biomarkers

One of the most frequent issues in newborns is acute kidney injury (AKI), which can lengthen their hospital stay or potentially raise their chance of dying. The gut-kidney axis establishes a bidirectional interplay between gut microbiota and kidney illness, particularly AKI, and demonstrates the importance of gut microbiota to host health. Since the ability to predict neonatal AKI using blood creatinine and urine output as evaluation parameters is somewhat constrained, a number of interesting biomarkers have been developed. There are few in-depth studies on the relationships between these neonatal AKI indicators and gut microbiota. In order to gain fresh insights into the gut-kidney axis of neonatal AKI, this review is based on the gut-kidney axis and describes relationships between gut microbiota and neonatal AKI biomarkers.

Renal oximetry for early acute kidney injury detection in neonates with hypoxic ischemic encephalopathy receiving therapeutic hypothermia

BACKGROUND

Neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia are at high risk of acute kidney injury (AKI).

METHODS

We performed a two-site prospective observational study from 2018 to 2019 to evaluate the utility of renal near-infrared spectroscopy (NIRS) in detecting AKI in 38 neonates with HIE receiving therapeutic hypothermia. AKI was defined by a delayed rate of serum creatinine decline (< 33% on day 3 of life, < 40% on day 5, and < 46% on day 7). Renal saturation (Rsat) and systemic oxygen saturation (SpO2) were continuously measured for the first 96 h of life (HOL). Renal fractional tissue oxygen extraction (RFTOE) was calculated as (SpO2 - Rsat)/(SpO2). Using renal NIRS, urine biomarkers, and perinatal factors, logistic regression was performed to develop a model that predicted AKI.

RESULTS

AKI occurred in 20 of 38 neonates (53%). During the first 96 HOL, Rsat was higher, and RFTOE was lower in the AKI group vs. the no AKI group (P < 0.001). Rsat > 70% had a fair predictive performance for AKI at 48-84 HOL (AUC 0.71-0.79). RFTOE ≤ 25 had a good predictive performance for AKI at 42-66 HOL (AUC 0.8-0.83). The final statistical model with the best fit to predict AKI (AUC = 0.88) included RFTOE at 48 HOL (P = 0.012) and pH of the infants' first postnatal blood gas (P = 0.025).

CONCLUSIONS

Lower RFTOE on renal NIRS and pH on infant first blood gas may be early predictors for AKI in neonates with HIE receiving therapeutic hypothermia. A higher resolution version of the Graphical abstract is available as Supplementary information.

Biomarkers for acute kidney injury in children - where are we now?

PURPOSE OF REVIEW

Review the literature over the last 2 years on commonly evaluated biomarkers of acute kidney injury (AKI) and highlight the findings of these biomarkers.

RECENT FINDINGS

Among several studied AKI biomarkers, urine neutrophil gelatinase-associated lipocalin (NGAL) and the combination of urine tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) have been recently studied most frequently as diagnostic biomarkers of AKI and for AKI risk stratification. Urine NGAL has continued to show good discriminative value to predict and diagnose AKI in childhood. Urine TIMP-2∗IGFBP7 can provide modest improvement to clinical models of AKI.

SUMMARY

Prior research supports that AKI biomarkers may identify AKI at an earlier time point and indicate clinically meaningful tubular injury. More effort should be made to understand if AKI biomarkers can guide treatments and improve outcomes.

Neonatal AKI: An update

Neonatal acute kidney injury (AKI) is a common complication, especially in the neonatal intensive care unit, that is associated with long term consequences and poor outcomes. Early detection and treatment is critical. Currently, neonatal AKI is defined with urinary markers and serum creatinine, with limitations on early detection and individual treatment. There have been numerous biomarkers and risk factor scores that have been studied for their ability to predict neonatal AKI. To move towards personalized medicine, neonatal AKI must be categorized into phenotypes and subphenotypes that fully encapsulate the diverse causes and specific treatments. This review aims to advance our understanding of neonatal AKI detection through the use of biomarkers, subphenotypes, and phenotypes to move towards personalized treatment strategies.

Neonatal hypoxic ischemic encephalopathy increases acute kidney injury urinary biomarkers in a rat model

Hypoxic ischemic encephalopathy (HIE) is associated with acute kidney injury (AKI) in neonates with birth asphyxia. This study aimed to utilize urinary biomarkers to characterize AKI in an established neonatal rat model of HIE. Day 7 Sprague-Dawley rat pups underwent HIE using the Rice-Vannucci model (unilateral carotid ligation followed by 120 mins of 8% oxygen). Controls included no surgery and sham surgery. Weights and urine for biomarkers (NGAL, osteopontin, KIM-1, albumin) were collected the day prior, daily for 3 days post-intervention, and at sacrifice day 14. Kidneys and brains were processed for histology. HIE pups displayed histological evidence of kidney injury including damage to the proximal tubules, consistent with resolving acute tubular necrosis, and had significantly elevated urinary levels of NGAL and albumin compared to sham or controls 1-day post-insult that elevated for 3 days. KIM-1 significantly increased for 2 days post-HIE. HIE did not significantly alter osteopontin levels. Seven days post-start of experiment, controls were 81.2% above starting weight compared to 52.1% in HIE pups. NGAL and albumin levels inversely correlated with body weight following HIE injury. The AKI produced by the Rice-Vannucci HIE model is detectable by urinary biomarkers, which can be used for future studies of treatments to reduce kidney injury.

Neonatal multiple organ failure after perinatal asphyxia

Perinatal asphyxia is an event with far-reaching consequences that can lead not only to the development of neonatal encephalopathy, but also to multiple organ failure (MOF). This ailment may result from the redistribution of blood flow, which would preserve the perfusion of vital organs such as the heart, brain and adrenal glands at the expense of other organs. The objective of the study was to determine the incidence and aetiopathogenesis of failure in the organs most frequently involved in neonatal MOF following perinatal asphyxia. We conducted a systematic literature search in the PubMed, Scopus and Cochrane Library databases using the MeSH terms (ischemia AND hypoxia AND multiorgan dysfunction AND neonat*), (asphyxia AND multiorgan dysfunction AND neonat*) and (liver/kidney/digestive OR gastrointestinal/heart injury AND ischemia AND hypoxia AND neonat*). We selected clinical and preclinical studies published after 2000 and excluded case series, letters to the editor, cohort studies without comparison groups and abstracts. In this study, we found that MOF associated with perinatal asphyxia is a frequent phenomenon with a relevant impact on neonatal morbidity and mortality, as it can cause changes not only in the kidney, liver and gastrointestinal tract, but also cardiomyopathy if the ailment is protracted or severe.

Update on prognosis driven classification of pediatric AKI

Acute kidney injury (AKI) affects a large proportion of hospitalized children and increases morbidity and mortality in this population. Initially thought to be a self-limiting condition with uniformly good prognosis, we now know that AKI can persist and progress to acute kidney disease (AKD) and chronic kidney disease (CKD). AKI is presently categorized by stage of injury defined by increase in creatinine, decrease in eGFR, or decrease in urine output. These commonly used biomarkers of acute kidney injury do not change until the injury is well established and are unable to detect early stage of the disease when intervention is likely to reverse injury. The kidneys have the ability to compensate and return serum creatinine to a normal or baseline level despite nephron loss in the setting of AKI possibly masking persistent dysfunction. Though these definitions are important, classifying children by their propensity for progression to AKD and CKD and defining these risk strata by other factors besides creatinine may allow for better prognosis driven discussion, expectation setting, and care for our patients. In order to develop a classification strategy, we must first be able to recognize children who are at risk for AKD and CKD based on modifiable and non-modifiable factors as well as early biomarkers that identify their risk of persistent injury. Prevention of initial injury, prompt evaluation and treatment if injury occurs, and mitigating further injury during the recovery period may be important factors in decreasing risk of AKD and CKD after AKI. This review will cover presently used definitions of AKI, AKD, and CKD, recent findings in epidemiology and risk factors for AKI to AKD to CKD progression, novel biomarkers for early identification of AKI and AKI that may progress to CKD and future directions for improving outcome in children with AKI.