Journal of Clinical Neonatology

: 2020  |  Volume : 9  |  Issue : 2  |  Page : 121--124

Incidence, risk factors, and outcome of acute kidney injury in hospitalized term newborns

N Nandhagopal, Uzma Firdaus, Syed Manazir Ali, Kamran Afzal 
 Department of Pediatrics, Jawaharlal Nehru Medical College, A. M. U, Aligarh, Uttar Pradesh, India

Correspondence Address:
Dr. Uzma Firdaus
Department of Pediatrics, Jawaharlal Nehru Medical College, A. M. U, Aligarh, Uttar Pradesh


Background: Acute kidney injury (AKI) is a common and devastating medical condition. However, the true incidence of AKI around the world is not known. In newborns patients, AKI importance and dilemmas are even more pronounced, as a newborn's kidneys are more susceptible to hypoperfusion and have low glomerular filtration rate. Objective: The objective is to determine the incidence, risk factors, and outcome of AKI in term newborns. Design: Prospective observational. Study Setting: Neonatology Division, Department of Pediatrics, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh. Methods: A hospital-based prospective study was done on 160 term inborn newborns. Babies were closely examined for the occurrence of AKI based on rising creatinine level or falling urine output. Results: The mean birth weight and the mean gestational of the study population were 2.64 (standard deviation [SD] 0.52) and 38.4 weeks (SD 1.05), respectively. Thirty-five babies developed AKI between 24 and 48 h of life. On applying nRIFLE criteria, 21, 7, and 7 babies fell into Stage 1 (risk), Stage 2 (injury), and Stage 3 (failure), respectively. At discharge, all babies showed normalization of renal function test and follow-up ultrasound at 3 months of age did not show any significant abnormality. The presence of asphyxia, comorbid sepsis, and circulatory collapse were found to have a significant association with AKI. The stage of AKI as per nRIFLE criteria significantly affected the outcome of newborns. Conclusion: AKI is a significant problem seen in newborns admitted to NICU. The most common risk factors identified were perinatal asphyxia, sepsis, and circulatory failure. There is a pressing need to improve antenatal care to decrease the burden of asphyxiated newborn and preventing hospital-acquired infection. This may translate into future wellbeing of the newborns.

How to cite this article:
Nandhagopal N, Firdaus U, Ali SM, Afzal K. Incidence, risk factors, and outcome of acute kidney injury in hospitalized term newborns.J Clin Neonatol 2020;9:121-124

How to cite this URL:
Nandhagopal N, Firdaus U, Ali SM, Afzal K. Incidence, risk factors, and outcome of acute kidney injury in hospitalized term newborns. J Clin Neonatol [serial online] 2020 [cited 2020 Jun 1 ];9:121-124
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Although acute kidney injury (AKI) is a common and devastating medical condition, the true incidence of AKI around the world is not known.[1],[2],[3] The burden of AKI in children and even neonates appears to be increasing, more so in the developing countries.[4],[5] The neonatal kidney is particularly vulnerable to the effects of hypoperfusion since the renal vascular resistance and plasma renin activity are high.[6] Critically, ill neonates are at even greater risk as they are commonly exposed to nephrotoxic medications and have frequent infections, which may lead to multiorgan failure. A large multicentric study found gestation-wise distribution of AKI cases to follow a U-shaped distribution with highest rates in the youngest (22–29 weeks) and oldest (>36 weeks) newborns.[7] Most of the works done in neonatal AKI using modern AKI definitions have included only special neonatal populations.[8],[9] AKI epidemiology in a general neonatal intensive care unit (NICU) has scarcely being studied. We undertook the current study to identify the incidence of AKI in our cohort of admitted neonates as well as classify them based on nRIFLE criteria.[10] We also evaluated their outcome and explored the risk factors for the development of AKI.


This prospective observational study was conducted in the Neonatology Division of the Department of Pediatrics, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, from January 2015 to September 2016. The study was approved by the institutional ethics committee. One hundred and sixty consecutively hospitalized term newborn babies in the NICU were screened for eligibility. Of these 20 babies did not fulfill the inclusion criteria and were excluded. Newborns with congenital anomalies of the urinary system, having expected hospital stays less than 48 h and with deranged maternal Renal Function Test (RFT) were excluded from the study.

Maternal and neonatal details as well as the findings of neonatal examination were entered into the predesigned pro forma. The diagnosis of AKI was established by measuring the serum creatinine level or urine output. In babies, who fulfilled the criteria for AKI, repeat estimations of serum creatinine were done every 48 h (or earlier if indicated) till it was normalized or the baby was discharged from the hospital. Normal serum creatinine values used for this study were 0.3–1.0 mg/dl.[10] Urine output was recorded in all male newborns by attaching urine collecting bag to the perineal area and in female newborns whenever they were catheterized. Urine output measurement was done six hourly and was noted in terms of ml/kg/h for that period.

The elevation of serum creatinine value by 1.5, 2, and 3 times from the baseline values was considered as Stage 1, 2, and 3 of renal failure, respectively. Similarly, urine output ≤1.5 ml/kg/h for 8 h, <1 ml/kg/h for 24 h, and <0.7 ml/kg/h for 24 h or anuria for 12 h was defined as Stages 1, 2, and 3 oliguric renal failure, respectively.[9] All the babies after discharge were followed up till 3 months of age in the high-risk clinic of the department of pediatrics. At completed 3 months of age, repeat RFT and ultrasonography of the abdomen of the newborn were done for the estimation of renal size, echotexture, and corticomedullary differentiation.

The SPSS version 21.0 (SPSS Inc., Chicago, IL) was used for the entry and analysis of data. The Chi-square test was used to compare categorical variables, and unpaired t-test was used for comparing continuous variables. P <0.05 was considered as statistically significant.


Out of 160 admitted newborns that completed the study, 35 (21.87%) babies developed AKI as defined by nRIFLE criteria. The mean (standard deviation [SD]) birth weight and gestational age of the study group were 2.64 (0.52) kg and 38.4 (1.0) weeks, respectively. Male to female ratio was 1.8:1. The mode of delivery was vaginal in 68 (42.5%) and the rest were born through caesarean section. The mean time (SD) of the occurrence of AKI was 2.28 (0.71) days. Mean time (SD) to the resolution of AKI and mean length (SD) of hospital stay were 12.47 (4.732) days and 14.29 (8.33) days, respectively. The presence of AKI prolonged the mean duration of hospital stay significantly (odds ratio: 4.8, confidence interval: 2.4–7.1, P < 0.001). All the babies demonstrated normalization of renal functions at discharge except one baby who did it on follow-up at 3 months of age. By following nRIFLE criteria for serum creatinine, out of 35 babies with AKI, 21 reached Stage 1, 7 babies reached Stage 2 while 7 others reached Stage 3. Twenty-six babies had urine output decreasing to oliguric range with stage-wise distribution being 8, 6, and 12 babies for Stages 1, 2, and 3, respectively. Majority of the babies (18 babies, 69.2%) became oliguric within 24 h of life while 8 were oliguric by 72 h of life. Nine babies continued to have urine output above the oliguric cutoff.

None of the maternal risk factors were found to be associated with the development of AKI in the newborn. Among the neonatal factors, the presence of sepsis, shock, and birth asphyxia was significantly associated with AKI both on univariate as well as logistic regression analysis [Table 1].{Table 1}

While evaluating the outcome of babies with AKI, we found shock and need for mechanical ventilation to be independent risk factors for mortality [Table 2] and [Table 3].{Table 2}{Table 3}

In the absence of standard criteria to define AKI, most of the previous researchers utilized an arbitrary cut off of 1.5 mg/dl of serum creatinine to define AKI.[11],[12],[13],[14],[15],[16],[17] We however had an important observation regarding 19 newborns from our study group who did not have the creatinine level rising to 1.5 mg/dl at the development of AKI.. Even on following these 19 newborns, only 2 showed elevation of serum creatinine beyond 1.5 mg/dl. This is an important finding as following the arbitrary definition for AKI, more than half (19 of 35) of the babies would have been missed as having AKI. This might have resulted in delay in instituting meticulous fluid management and renal modification of nephrotoxic medication doses.


Acute renal failure and AKI have traditionally been used to describe an abrupt decline in renal function. Pediatric RIFLE (pRIFLE) criteria were created by the acute dialysis quality initiative group and have been modified thrice. The first modification was the pRIFLE. The second was modification into AKI network (AKIN) criteria to include increase of 0.3 mg/dl of serum creatinine within 48 h period. The most recent is the Kidney Disease Improving Global Outcomes classification system of 2012 which harmonizes the RIFLE, AKIN, and pRIFLE. However, various studies comparing these definitions could not establish the superiority of one above the other.

The incidence of AKI in term newborns hospitalized in general NICU based on nRIFLE criteria was found to be 21.8%. Among the neonatal comorbid conditions, sepsis, shock, and birth asphyxia were significantly associated with AKI. In this current study, 45.7% (16 babies) babies with AKI had coexistent sepsis. Many previous investigators have also identified sepsis, low birth weight, and shock to be significant factors for the development of AKI. Of 35 babies with AKI, 9 babies did not develop oliguria with the rising serum creatinine levels.

Most of the works on neonatal AKI have considered special neonatal groups and the incidence varies widely among the studies.[12],[18],[19],[20],[21],[22] This may partly be due to the lack of standard criteria for defining AKI in newborns. Much of the researches done in the past have utilized an arbitrary cutoff of serum creatinine as 1.5 mg/dl or 2 mg/dl for defining AKI. Nineteen out of 35 babies with AKI in our study group never reached the serum creatinine cut off of 1.5 mg/dl. Very few studies have used the urine output criterion for defining or classifying AKI as described in the nRIFLE. However, the incidence of oliguria varies widely in different studies.[12],[14],[19],[20],[21],[22]

The limitation of the present study was that the urine output was not measured in all female neonates. The babies were followed after discharge till 3 months of age. The possible later occurrence of ill effects of AKI on the growth, blood pressure, or renal functions of the babies could not be explored in this study.

The neonatal kidney is particularly vulnerable to the effects of hypoperfusion owing to high renal vascular resistance as well as high plasma renin activity. Any condition compromising the circula11tion like falling cardiac output or intravascular volume, as well as peripheral vasodilatation can potentially compromise the labile renal circulation. Meticulous fluid management, maintenance of cardiac output and judicious use of nephrotoxic medications is desirable. Future research should focus on exploring the feasibility of utilizing the new definition of AKI for standardization. In addition, novel markers of kidney injury also need to be tested in special groups of newborns as well as babies in the general NICU.


AKI is a common problem of hospitalized term newborns. The presence of AKI prolongs the duration of hospital stay as well increases the risk of mortality in the newborns. Majority of babies are likely to develop lower stages of AKI. The arbitrary cutoff of 1.5 mg/dl for serum creatinine for de11fining AKI is likely to miss more than half of the cases of AKI. The independent predictors for the development of AKI are asphyxia, sepsis, and shock. The use of mechanical ventilation and shock are the predictors of mortality in AKI.

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Conflicts of interest

There are no conflicts of interest.


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