Acute kidney injury (AKI) occurs frequently in the neonatal intensive care unit (NICU), yet often is undetected. Multiple studies have confirmed AKI detection and documentation rates are low

with only 4–26% of AKI survivors having AKI recorded in the discharge summary [1,2,3]. Carmody et al. found AKI occurred in ~40% of very low birthweight infants but was recorded in the

discharge summary in only 13.5% of survivors [4]. The accurate diagnosis and documentation of AKI is pivotal to ensure appropriate pediatric nephrology referral occurs, a key component to

ensuring subsequent follow-up of neonates at risk for chronic kidney disease (CKD) [3]. While the available literature confirms AKI is under-diagnosed in the NICU, few studies have

pre-existing end stage kidney failure, a palliative care course within the first week of life or were transferred to Medical University of South Carolina (MUSC) NICU at greater than 48 h of

life. We hypothesized 40% of AKI episodes would be undiagnosed. The modified neonatal _Kidney Disease: Improving Global Outcomes_ serum creatinine criteria was used to define AKI.

Comparisons were made between neonates in whom AKI was identified by the medical team during the NICU stay (‘detected AKI’) and neonates in whom AKI was not diagnosed in the NICU but was

identified by the research team on chart review (‘missed AKI’). Statistical methods included Chi Square, Fisher’s Exact, Student’s _t_, and Wilcoxon rank sum tests. The study was approved by

the MUSC Institutional Review Board which granted a waiver of informed consent. Of the 869 neonates included, 164 (18.9%) experienced an AKI episode while in the NICU, with a total of 308

AKI episodes. Of those neonates, 73 (44.5%) had detected AKI (174 episodes) and 91 (55.5%) had missed AKI (134 episodes). Compared to those with detected AKI, neonates with missed AKI had

higher birth weight (BW, Missed: 1870 ± 888 g, Detected: 1509 ± 1124 g; _p_ = 0.03), higher gestational age (GA, Missed_:_ 32.4 ± 4.4 weeks, Detected: 29.0 ± 5.8 weeks; _p_ < 0.01), and

were more frequently male (Missed_:_ 62.6%, Detected_:_ 46.6%; _p_ = 0.04). Neonates with missed AKI experienced shorter median durations of mechanical ventilation (Missed_:_ median 2 days

(0–15), Detected: 19 days (5–43); _p_ < 0.01) and hospitalization (Missed: median 58 days (22–90), Detected: 75 days (28–113); _p_ < 0.03), and more frequently survived (Missed 93.4%,

Detected: 79.5%; _p_ < 0.01). Important differences in AKI severity were identified when comparing those with detected AKI to those with missed AKI (all _p_ < 0.05, Table). The

majority of missed AKI episodes were stage 1 AKI (114/134, 85.1%), but 20 episodes (14.9%) of missed AKI were stage 2 AKI (_p_ < 0.05). No stage 3 AKI episodes were missed (Table 1).

Known risk factors for AKI including patent ductus arteriosus, sepsis, nephrotoxic medication exposure, hypoxic ischemic encephalopathy, and hypotension requiring pressors were less common

in neonates with missed AKI (all _p_ < 0.05, Table 1). Caffeine citrate exposure was less common in those with missed AKI (_p_ < 0.05). Perhaps most importantly, in the cases of missed

AKI, pediatric nephrology consultation was less common (Missed: 20.9%, Detected: 71.2%, _p_ < 0.001) and referrals for outpatient pediatric nephrology care were less frequently completed

(Missed_:_ 15.4%, Detected_:_ 60.3%; _p_ < 0.001). However, some infants, even without AKI, were presumably referred to pediatric nephrology due to other kidney issues. Pediatric

nephrology follow-up is conducted in a dedicated, pediatric nephrology clinic and consists of blood pressure measurements and serum creatinine levels. Limitations in our study included

reliance on clinical documentation in the electronic medical record which can be incomplete and the potential for missed AKI episodes because of not assessing urine output due to difficulty

of measuring urine output in infants. A single neonatal AKI episode is acutely associated with increased mortality and may lead to CKD with persistence of renal dysfunction into early

childhood [5]. Therefore, improvement in recognition and diagnosis of AKI remain important next steps in reducing morbidity and mortality, both in the NICU and later in life. Without early

recognition, appropriate outpatient follow-up cannot occur. Following even one AKI episode, neonates are at risk of developing hypertension, hyperfiltration, proteinuria, and/or other signs

of chronic kidney disease. When unrecognized these morbidities could go undetected, delaying treatment, resulting in disease progression. Collaboration between neonatology and pediatric

nephrology is critical for the accurate diagnosis and documentation of AKI in critically ill neonates. Chmielewski _et al_. found pediatric nephrology consultation in neonates with AKI

strongly mediated AKI diagnosis and documentation at discharge [3]. Starr et al. found standardized approaches improve neonatal AKI identification in the NICU, even when protocols vary

between institutions [1]. Electronic health record-automated detection may be helpful in some centers, and ongoing education for care team members will likely be required. Further work and

future studies to determine the best care model to ensure AKI recognition are needed. Despite highly protocolized AKI care in our NICU, AKI detection remains low, particularly in neonates

with higher BW, later GA, and in those who experience less severe AKI and fewer risk factors for AKI. Therefore, ongoing education is warranted, even in a setting where neonatal AKI is

protocolized, researched, and frequently discussed. DATA AVAILABILITY Currently, due to IRB restrictions, these data are not publicly available. REFERENCES * Starr MC, Chaudhry P, Brock A,

Vincent K, Twombley K, Bonachea EM, et al. Improving the identification of acute kidney injury in the neonatal ICU: three centers’ experiences. J Perinatol. 2022;42:243–6. Article  PubMed 

Google Scholar  * Roy JP, Goldstein SL, Schuh MP. Under-Recognition of Neonatal Acute Kidney Injury and Lack of Follow-Up. Am J Perinatol. 2022;39:526–31. Article  PubMed  Google Scholar  *

Chmielewski J, Chaudhry PM, Harer MW, Menon S, South AM, Chappell A, et al. Documentation of acute kidney injury at discharge from the neonatal intensive care unit and role of nephrology

consultation. J Perinatol. 2022;42:930–6. Article  PubMed  PubMed Central  Google Scholar  * Carmody JB, Charlton JR. Short-term gestation, long-term risk: prematurity and chronic kidney

disease. Pediatrics. 2013;131:1168–79. Article  PubMed  Google Scholar  * Harer MW, Pope CF, Conaway MR, Charlton JR. Follow-up of Acute kidney injury in Neonates during Childhood Years

(FANCY): a prospective cohort study. Pediatric Nephrol. 2017;32:1067–76. Download references ACKNOWLEDGEMENTS All work for this study was performed at the Medical University of South

Carolina in Charleston, South Carolina. FUNDING This project was funded in part by the David and Laura Stone Endowment for Advancement in Neonatal Medicine, Division of Neonatology, Medical

University of South Carolina. Open access funding provided by the Carolinas Consortium. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Pediatrics, Medical University of South

Carolina, Charleston, SC, USA Katherine Vincent, Austin Rutledge, David T. Selewski & Heidi J. Steflik * Department of Pediatrics, Cincinnati Children’s Medical Center, Cincinnati, OH,

USA Zegilor Laney * Department of Medicine, Medical University of South Carolina, Charleston, SC, USA Jill C. Newman Authors * Katherine Vincent View author publications You can also search

for this author inPubMed Google Scholar * Zegilor Laney View author publications You can also search for this author inPubMed Google Scholar * Austin Rutledge View author publications You

can also search for this author inPubMed Google Scholar * Jill C. Newman View author publications You can also search for this author inPubMed Google Scholar * David T. Selewski View author

publications You can also search for this author inPubMed Google Scholar * Heidi J. Steflik View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS

KV contributed substantially to the conception and design of this project, the acquisition, analysis and interpretation of these data, the drafting and critical revision of this paper, and

she approves the final version as published and agrees to be accountable for all aspects of the work. ZL and AR contributed substantially to the acquisition of the data for this work,

critical revision of this paper, and they a approves the final version as published and agree to be accountable for all aspects of the work. DTS and HJS contributed substantially to the

conception and design of this project, the interpretation of these data, critical revision of this paper, and they approve the final version as published and agrees to be accountable for all

aspects of the work. JCN contributed substantially to the analysis and interpretation of these data, critical revision of this paper, and she approves the final version as published and

agrees to be accountable for all aspects of the work. CORRESPONDING AUTHOR Correspondence to Katherine Vincent. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing

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from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Vincent, K.,

Laney, Z., Rutledge, A. _et al._ Recognition of acute kidney injury diagnosis in the neonatal intensive care unit. _J Perinatol_ 44, 1792–1794 (2024).

https://doi.org/10.1038/s41372-024-02095-y Download citation * Received: 20 March 2024 * Revised: 22 July 2024 * Accepted: 12 August 2024 * Published: 22 August 2024 * Issue Date: December

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