The Utility of Serum cystatin C as a Biomarker for Acute Kidney Injury in Preterm Neonates with Respiratory Distress Syndrome

Abstract

SUMMARY R DS is the most common respiratory disorder of premature newborns and it is a common cause of neonatal death and disability. Despite recent advances in perinatal and neonatal care in RDS prevention and treatment, a considerable number of these neonates suffer from acute kidney injury (Koralkar et al., 2011, Elmas et al., 2013a). The aim of this work was to evaluate the value of SCysC measurement as an early predictor of acute kidney injury in preterm neonates with respiratory distress syndrome. Our study was carried on 75 preterm neonates divided into 2 groups: cases group included 50 preterm neonates with RDS that stratified into two subgroups according to development of AKI as RDS_AKI subgroup (n=13) and RDS_ non AKI subgroup (n=37). The diagnosis was based on modified pediatric RIFLE (pRIFLE) criteria (Zubarioğlu et al., 2013).Their mean GA was (31.77 ± 1.95) wks and BW was (1.55 ± 0.44) kg. The control group included 25 healthy preterm neonates without RDS. Their mean GA was (32.10 ± 1.87) wks and BW was (1.87 ± 0.32) kg.

Diagnosis of AKI was based on: • Serum Cr > 1.5 mg/dl on the first 3 days of life (sustained at least 48 h while the mother of the neonate had normal renal function). • Modified pediatric RIFLE (pRIFLE) criteria. pRIFLE criteria were as follows; R (risk): a ≥25 % decrease in estimated GFR and/or urine output <0.5 ml/kg/h for 8 h. I (injury): a ≥50% decrease in estimated GFR and/or urine output<0.5ml/kg/hfor16h. F (failure): a ≥75 % decrease in estimated GFR from baseline renal function and/or urine output <0.3 ml/kg/h for 24 h. Estimated GFR (ml/min/1.73m2) was calculated at PND3 and GFR was estimated using the Schwartz Formula. Estimated GFR: k × height/Cr, the constant k was used as 0.33 for neonates who were born before GW 34. Both groups were subjected to complete history taking, thorough clinical examination, laboratory investigations including CBC, CRP, BUN, Cr. Serum samples were collected in PND3 from cases and controls in order to detect S Cys C levels by ELIZA. Our study showed no significant correlation between Cys C D3 levels in AKI neonates and (GA, BW, Apgar scores1, Downes' score, GFR D3, Cr.D3 and BUN.D3), (p>0.05). Yet, there was a significant correlation with (Apgar score 5 min, GFR D5&D7, Cr.D5&D7 and BUN.D5&D7), (p< 0.05). In our study, There was no statistical significant difference between patients and controls regarding GA, gender and mode of delivery, (p >0.05) yet, BW, Apgar scores (at 1 and 5 min) and PH upon admission were significantly lower among RDS group compared to control group whereas Downes' score were significantly higher, (p< 0.05). Our study showed that there was no significant difference between RDS group and controls regarding sepsis and fate, (p> 0.05) whereas neonates in RDS group stayed significantly longer period in NICU than controls, (p< 0.05). Our study also demonstrated that 26% of RDS neonates had developed AKI (based on the definition used). Only 30.8% of AKI neonates developed oliguria with 23.1% neonatal mortality within the same group. In our study, there was no statistical significant difference between RDS_AKI group & RDS_ non AKI group regarding BW, Apgar scores at 1 min, Downes' score and PH upon admission, (p> 0.05) yet, GA and Apgar scores at 5 min were significantly lower among RDS_AKI group compared to RDS_ non AKI group, (p< 0.05).