Kidney disease in premature infants and critically ill neonates is a growing problem. One in 10 children is born prematurely each year (1). In these neonates, improvements in neonatal intensive care have increased survival and shifted focus to long-term outcomes. Kidney-related outcomes are increasingly recognized in this population (2). Children born prematurely have a 3-fold increased risk of chronic kidney disease (CKD) and a 1.5-fold increased risk of end-stage kidney disease over the life course compared to children born full term (2, 3). This clinical problem will continue to grow as more survive prematurity into adulthood.
Neonates admitted to the neonatal intensive care unit (NICU) may be inherently at increased risk of CKD (4, 5). In those born prematurely, this risk is thought to result from disrupted nephrogenesis, resulting in a lower nephron number. In addition, acute kidney injury (AKI) occurs in up to 30% of high-risk neonates admitted to the NICU from both intrinsic factors (including low nephron number, low glomerular filtration rate [GFR], and tubular immaturity) and extrinsic factors (such as increased insensible losses and nephrotoxic medications) (6, 7). Infants who survive NICU admission and had an episode of AKI are at increased risk for repeated episodes of AKI as well as CKD (8). All patients, including infants, surviving an episode of AKI should have long-term monitoring for CKD. Unfortunately, the diagnosis of AKI remains underrecognized, made in only 10%-30% of neonates (9). The reasons for under-diagnosis are complicated but likely related to underrecognized, subtle changes in serum creatinine that reflect significant alterations in GFR and a lack of awareness of neonatal AKI definitions (10). Without clinical recognition of the impact of preterm birth and AKI on CKD risk, many neonates are not identified for long-term kidney follow-up, reducing providers' ability to identify CKD early. Children are not routinely screened for kidney disease, and those who develop CKD often do not experience symptoms until the kidney damage is severe and irreversible. Healthcare costs increase fourfold with a late-stage CKD diagnosis (11, 12).
One potential solution to this gap in AKI diagnoses and follow-up after preterm birth and AKI is increasing nephrology integration into the NICU. Studies show programs that integrate early pediatric nephrologist consultation into the NICU improve AKI diagnosis (13). There are multiple models that have been implemented successfully, including nephrology consults on all NICU patients with AKI identified by electronic medical record review (Riley Children's Hospital). Some centers lead weekly NICU nephrology rounds in which all neonates with AKI are evaluated by a nephrologist (Nationwide Children's Hospital). Other centers have developed local guidelines for neonatologists to support AKI recognition and consultation with pediatric nephrology (Medical University of South Carolina and University of North Carolina).
No matter the model, we strongly believe that the integration of pediatric nephrology providers into NICUs improves the recognition and management of AKI and increases follow-up of patients at high risk for future CKD. The importance of neonatal nephrology integration is especially valuable in the NICU where the diagnosis of AKI is challenging. A Neonatal Nephrology Program emphasizes early referral to a nephrology clinic and facilitates discussion of kidney health monitoring, early identification of CKD, and risk reduction. Early identification of pediatric patients with CKD is essential to slow the progression of kidney disease, as it allows for the initiation of treatment to improve kidney function into adulthood.
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