Evidence Based Strategies: Caring About Creatinine: Acute Kidney Injury Follow-Up in the Pediatrician’s Office

Column Author: Bahar Barani, MD | Chief Resident

Darcy Weidemann, MD, MHS | Associate Professor Division of Nephrology  

Column Editor: Angela D. Etzenhouser, MD, FAAP | Associate Director, Pediatric Residency Program Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Pediatric acute kidney injury (AKI) in the hospital has significant implications for the development of chronic kidney disease (CKD) and hypertension in the future. Outpatient providers can play an essential role in identifying these patients earlier in their CKD and hypertension courses, mitigating long-term sequelae of these processes.

Acute kidney injury is defined as a loss of kidney function in an acute period. Acute kidney injury is typically quantified in the clinical setting by an increase in serum creatinine of at least 1.5 times baseline within seven days or an increase of at least 0.3 mg/dL within 48 hours. Urine output criteria include a drop in urine output to less than 0.5 ml/kg per hour for a six- to 12-hour range. AKI is increasingly common in the hospital setting and a significant source of morbidity in hospitalized pediatric patients. One study estimated that up to 31% of non-ICU pediatric patients experience AKI at some point during their admission. Patients in the pediatric intensive care unit (PICU) and neonatal intensive care unit (NICU) likely have even higher rates during their courses. The majority (86.1%) of children are exposed to at least one potentially nephrotoxic medication during their hospital course. This percentage is especially significant given the long-term risk associated with AKI in the development of CKD and hypertension.

Certain inpatient populations with AKI are at significantly higher risk for long-term chronic kidney disease and hypertension. One example is premature infants with stays in the NICU. One cohort study by Dyson et al. highlighted that extremely preterm infants may have up to triple the risk of developing CKD than the general population. Children who received dialysis at any time during their inpatient course appear to be at extremely increased risk for major adverse kidney events. In a recent population-based retrospective cohort study, after around a decade of follow-up, pediatric dialysis AKI survivors demonstrated increased risk for kidney failure and death (adjusted hazard ratio (aHR) of 2.96), de novo CKD (aHR = 8.7), and de novo hypertension (aHR 3.35). Thus, in the outpatient setting, we can further tailor appropriate disease surveillance and prevention strategies to those patients at highest risk.

Due to this risk for sequelae, it is recommended that patients with acute kidney injury in the hospital setting have follow-up focused on post-AKI care with a provider within three months if their AKI resolved prior to discharge and in three weeks if the AKI has not resolved completely at time of discharge. Despite this recommendation, significant barriers exist to ensuring this occurs. A recent retrospective cohort study by Robinson et al. tracked PICU survivors of AKI and noted that only 18% of those who survived AKI at one institution had follow-up with a nephrologist. This finding is supported by similar data in the literature highlighting low rates of AKI-specific nephrology follow-up. However, 95% of these children in the study were seen within a year by either a family practitioner, pediatrician or other subspecialist. Thus, significant health care interactions occur for these patients, and there is ample opportunity for post-AKI follow-up to mitigate the sequelae of chronic kidney disease and hypertension.

Follow-up for AKI should include a serum creatinine, blood pressure check and random urine protein. Additionally, follow-up provides an opportunity to counsel on appropriate use of potentially nephrotoxic medications (such as non-steroidal anti-inflammatories), appropriate hydration, and ensuring medications are adjusted for decreased eGFR if appropriate. Indications for referral to a nephrologist include patients noted to have hypertension using age- and height-based percentiles, 1+ or greater proteinuria on a first morning urine void, or an eGFR that is below 90% of baseline. eGFR can be calculated using the CKiD U25 equation, which is readily available as a calculator online (https://ckid-gfrcalculator.shinyapps.io/eGFR/).

Early detection of CKD can improve long-term outcomes for AKI survivors in terms of long-term kidney prognosis and cardiovascular health into adulthood. Because primary care providers are more likely to have follow-up with children discharged from the hospital after AKI, they can make a major positive impact by identifying AKI history and providing appropriate follow-up care.

References:

Dyson A, Kent AL. The effect of preterm birth on renal development and renal health outcome. Neoreviews. 2019;20(12):e725-e736. doi:10.1542/neo.20-12-e725

Levin A, Stevens PE. Early detection of CKD: the benefits, limitations and effects on prognosis. Nat Rev Nephrol. 2011;7(8):446-457. doi:10.1038/nrneph.2011.86

Parikh RV, Tan TC, Salyer AS, et al. Community-based epidemiology of hospitalized acute kidney injury. Pediatrics. 2020;146(3):e20192821.

Pierce CB, Muñoz A, Ng DK, Warady BA, Furth SL, Schwartz GJ. Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease. Kidney Int. 2021;99(4):948-956. doi:10.1016/j.kint.2020.10.047

Robinson CH, Iyengar A, Zappitelli M. Early recognition and prevention of acute kidney injury in hospitalised children. Lancet Child Adolesc Health. 2023;7(9):657-670.

Robinson C, Hessey E, Nunes S, et al. Acute kidney injury in the pediatric intensive care unit: outpatient follow-up. Pediatr Res. 2022;91:209-217. doi:10.1038/s41390-021-01414-9

Dharnidharka VR. Ciccia EA, Goldstein SL. Acute kidney injury in children: being AWARE. Pediatrics. 2020;146 (3):e20200880. doi:10.1542/peds.2020-0880

Robinson CH, Jeyakumar N, Luo B, et al. Long-term kidney outcomes following dialysis-treated childhood acute kidney injury: a population-based cohort study. J Am Soc Nephrol. 2021;32(8):2005-2019. PMID: 34039667. PMCID: PMC8455253. doi:10.1681/ASN.2020111665