Acute Kidney Injury (AKI), previously known as Acute Renal failure, is an abrupt decline in renal excretory function characterised by a reversible increase in the serum creatinine and nitrogenous waste products.Acute kidney injury (AKI) in childhood nephrotic syndrome is an uncommon but serious complication resulting from intravascular volume depletion, acute tubular necrosis, interstitial nephritis, bilateral renal venous thrombosis or rapid progression of underlying glomerular disease1. Sepsis, shock, peritonitis, severe hypoalbuminemia, nephrotoxic drugs exposure and steroid resistance are important risk factors for AKI in childhood nephrotic syndrome2-5. 

The underlying pathophysiology includes decreased renal perfusion due to various causes resulting in decreased urine output, rising serum creatinine, deranged fluid and electrolyte homeostasis, reduction in the immunity thereby affecting various organ systems6. AKI can be divided into pre-renal injury, intrinsic kidney disease (including vascular insults) and obstructive uropathies.  Children are found to be more susceptible to injury than adults and more so in females in comparison to male children. Acute renal insufficiency is a well-recognized complication in idiopathic nephrotic syndrome with minor glomerular abnormality.Several possible mechanisms for acute renal insufficiency in the nephrotic syndrome include hypovolemia7, alterations in intrarenal hemodynamics8, renal vein thrombosis9, drug-induced interstitial nephritis10, ischemic acute tubular necrosis11,12 and tubular obstruction by proteinaceous casts13.  The incidence of AKI was four-fold higher in critically ill patients (36.1%) compared to non-critically ill patients (0.9%)14. The incidence of AKI in southern India is found to be 5% in hospitalised patients and 30% in PICU.Multiple definitions for AKI have obviously led to a great disparity in the reported incidence of AKI making it difficult or even impossible to compare the various published studies focusing on AKI15,16. Nephrotic syndrome (NS) is one of the commonest kidney diseases seen in childhood6,17. It is characterised by heavy proteinuria, hypoalbuminemia and anasarca, and generally has a relapsing remitting course. Children with NS are at risk of developing complications like infection, venous thromboembolism (TE), hypovolemia, and acute kidney injury (AKI)17,14. While infections and TE can be partly explained by the significant proteinuria seen in NS, AKI in NS is more complicated. It is multifactorial in origin and can be secondary to intravascular volume depletion, acute tubular necrosis, interstitial nephritis, nephrotoxic medications, infections, or renal vein thrombosis14,18.

Aim

To determine the Incidence of Acute Kidney Injury in idiopathic nephrotic syndrome children admitted to Paediatric department of a Tertiary care centre.

This study was a prospective observational cross-sectional investigation aimed at assessing acute kidney injury (AKI) in hospitalised children with idiopathic nephrotic syndrome and those critically ill at the Department of Paediatrics, S.P. Medical College, Bikaner. The study was conducted over the course of one year, focusing on children aged 1 month to 14 years who were admitted to the department.The study sample consisted of 75 patients who met specific criteria. To be included, children had to be between the ages of 1 month and 14 years, diagnosed with idiopathic nephrotic syndrome, and hospitalised for a minimum of 48 hours during the study period. Parental consent was obtained for all participants.Exclusion criteria were carefully defined to ensure the study’s relevance and accuracy. Children were excluded if they were undergoing renal replacement therapy, including maintenance or peritoneal dialysis; had chronic kidney diseases or nephritis; had undergone renal transplantation; or had pre-existing acute kidney injury.The study aimed to identify and analyse the incidence of AKI in this particular patient group, using standard diagnostic criteria and methodologies to monitor and follow up on renal function and recovery.

Sample Size Estimation

Sample size was calculated using the formula:

4pq/d2

P- incidence of Acute Kidney Injury

Q- (1-P)

D - absolute precision

The prevalence of Acute Kidney injury in critically ill children were estimated to be around 25% based on current literature and assuming an variation of 10% (absolute precision d=0.10), the sample size was estimated to be around 75.

Statistical Analysis

The data collected regarding all the selected cases were entered in Microsoft excel sheet 2010. Results were analyzed using the SPSS version

19 (IBM corporation, New York, U.S.A). 

Table 1: Distribution of cases according to age (Years

Majority of cases belonged to age group 6-8 years (50.7%) followed by age groups <5 (34.7%) and 9-11 years (14.7%). 

Fig: Distribution of cases according to chief complaints

Majority of cases presented with generalized swelling (88%) followed by decrease urine output (82.7%), vomiting (41.3%).

Table 2: Distribution of cases according to hemoglobin (gm/dl)

Majority of patients had (82.7%) patients had hemoglobin >10gm/dl while 17.3% patients had hemoglobin <10gm/dl.

Table 3: Distribution of cases according to systemic examination (Respiratory System R/S)

Majority of patients (88%) had no abnormal findings and few patients had added sound (Crepts, Wheeze).

Table 4: blood urea (mg/dl)

Out of total 14 AKI patients, 9(64.3%) patients had their blood urea >100mg/dl while 5(35.7%) had their blood urea between 41-100mg/dl (p<0.001HS).

Table 5: serum creatinine (mg/dl)

All AKI patients had their serum creatinine level >1 (p<0.001).

Table 6: albumin (gm/dl)

Majority 97.3% cases of nephrotic patients had their serum albumin level <2.5gm/dl, while 2.7% patients had their albumin >2.5gm/dl (p<0.05).

Fig: total cholesterol

All nephrotic cases (100%) present had the TC > 200 (p<0.01S).

Fig: Distribution of cases according to Nephrotic Syndrome in relation to urine C/S

Majority of patients had their urine culture sterile while few patients had kleibsella (17.3%), pseudomonas (10.7%) and streptococcus (5.3%) (p<0.01S).

Table 7: Distribution of cases according to USG W/A & KUB

According to USG W/A & KUB examination, 61.3% patients had mild pleural effusion while 18.7% patients had moderate pleural effusion, 73.3% patients had ascitis and CMD was not maintained in 73.3% of patients.

Table 8: Distribution of cases according to duration of hospital stay (days)

Majority of patients (65.3%) patients were stayed at hospital between 6-10 days, while 18.7% and 16% patients were stayed at hospital >10 days and <5 days respectively.

Out of total 75 patients, most common age group was 5-8 years where total 85.4% patients were found. In our study, overall mean age 6.75±2.45 years (Table 1).

According to Agarwal et al19also found that most common age group was 5-7 years which were quite similar to our study. In a study conducted by Yaseen et al20 found that mean age was 8.8±3.59 years which is quite similar to our study.

According to presenting complaints (Table 4), out of total 75 patients 29.3% patients had cough, 6.7% patients had breathing difficulty, 82.7% patients had decrease urine output, 88% patients had generalized swelling, 24% patients had fever, 41.3% patients had vomiting while 20% patients had burning micturition. A study done by Anigilaje et al21 where they found that vomiting was present in 62.5% of cases. 

According to systemic respiratory examination (Table 10), out of 75 patients, 9(12%) had B/L AE and B/L Crepts while 66(88%) patients had B/L AE+ and NAD. Study done by Lu et al22 found that pulmonary infection was observed in 55.4% AKI patients and 9.7% of Non-AKI patients.

Out of total 75 patients, 13(17.3%) patients had anemia (Hb <10gm/dl), 23(30.7%) patients each had their hemoglobin between 10.111.0 and 11.1-12.0gm/dl while 16(21.3%) patients had their hemoglobin >12gm/dl. Mean hemoglobin in present study was 11.09± 1.38gm/dl (Table 12). Study conducted by Lu et al22 found the in AKI patients mean hemoglobin 14.5±2.81 and in Non-AKI patients mean hemoglobin was 14.6±3.05mg/dl which is supported our study.

Out of total 75 patients, all 14(100%) AKI patients had raised blood urea while in Non-AKI patients, 34(55.8%) patients had raised blood urea. Mean blood urea in AKI patients was 134.21±46.07mg/dl while mean blood urea in Non-AKI patients was 49.98±32.11mg/dl and the difference was found statistically highly significant (p<0.001) (Table 18).  Study conducted by Kim et al23 found that mean blood urea in AKI patients was found 32 and in Non-AKI patients mean blood urea was 12. Another study conducted by Lu et al22 found that mean blood urea in AKI and Non-AKI patients was 8.18±3.15 mg/dl and 4.75±2.11 mg/dl respectively.

Out of total 14 AKI patients, 9(64.3%) patients had raised serum creatinine while 5(35.7%) had their creatinine within normal range (Table 19). In Non-AKI patients, all 61(100%) patients had their serum creatinine within normal range. Mean SC in AKI patients was 1.91±0.54 mg/dl while mean SC in Non-AKI patients was 0.41±0.15 mg/dl and the difference was found statistically highly significant (p<0.001).  In a study conducted by Prasad et al16  found that mean serum creatinine in AKI patients was 0.9±0.7 mg/dl and in Non-AKI patients it was 0.5±0.1 mg/dl which is quite similar to our study in Non-AKI patients while a litter lower serum creatinine was observed in AKI patients in comparison to our study.

All 14(100%) AKI patients had their albumin level <2.5gm/dl while in Non-AKI patients, 59(96.7%) and 2(3.3%) patients had their albumin level <2.5 gm/dl and >2.5 gm/dl respectively (Table 20). Mean albumin in AKI and Non-AKI patients were 1.18±0.23 gm/dl and 1.50±0.51 gm/dl and the difference was found statistically significant (p<0.05).  Study conducted by Lu et al22 where they found that mean albumin in AKI patients was 1.94±0.50 gm/dl and in Non-AKI patients it was 2.41±0.83 gm/dl which is slight higher than our study. Another study conducted by Prasad et al16  found that mean albumin in AKI patients was 1.5±0.8 gm/dl and in Non-AKI patients it was 1.50±0.7 gm/dl which is similar to our study.

According to total cholesterol (Table 21), all 14(100%) patients of AKI had raised cholesterol while in Non-AKI patients 57(93.4%) patients had raised cholesterol level. Mean cholesterol in AKI patients was 429.85±70.47 mg/dl while in Non-AKI patients, mean cholesterol was 356.28±96.20 mg/dl and the difference was found statistically significant (p<0.01).  Lu et al22  found that mean total cholesterol in AKI patients was 85.90±37.6 mg/dl and in Non-AKI patients mean cholesterol was 18.7±10.2mg/dl which is quite lower than our study.

According to urine C/S (Table 23), out of total 14 AKI patients, kleibsella was observed in 5(35.7%) while pseudomonas was observed in 4(2.6%) while remaining 5(35.7%) were sterile. In Non-AKI patients, Kleibssella was observed in 8(13.1%) of cases, pseudomonas was observed in 4(6.6%) and streptococcus was observed in 4(6.6%) and the difference was found statistically highly significant (p<0.01).

According to USG W/A & KUB (Table 27), moderate pleural effusion was observed in 14l (18.7%) of patients. Ascitis was also observed in 55(73.3%) while CMD was not maintained in 55(73.3%) patients.

According to duration of hospital stay (days), 14(18.7% patients stayed at hospital for <5 days, 49(65.3%) patients had stayed at hospital between 6-10 days while 12(16%) patients stayed at hospital for >10 1days Mean hospital stay was 9.27±5.76 days (Table 28).   A study conducted by Wang et al24 found the mean hospital stay was 4.0 days which is lower than our study. According to Prasad et al16 mean hospital stay in died patients was 16 days and in survivor patients mean hospital was 7 days which is quite similar to present study.

Acute kidney injury (AKI) is an alarming complication of idiopathic nephrotic syndrome. In conclusion, our study examined NS disease management and inpatient and outpatient usage and described the associations between clinical and demographic characteristics and disease outcome. This study indicates that AKI is common in our children with NS. This should be concerning and the need for close observation to allow for prompt diagnosis of AKI and management, therefore, be overemphasized. We found the main risk factors of AKI to include sepsis, gross haematuria, UTIs, peritonitis, and exposure to potentially nephrotoxic medications. While efforts at recognizing these risk factors of AKI among our children with NS are important, we also propose a large prospective multi-centre study to characterize the risk factors of AKI and its long-term outcomes among Indian children with NS.

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