Avaliação de biomarcadores da função renal em crianças nascidas prematuras em um hospital universitário do nordeste brasileiro

Abstract

This thesis aimed to evaluate biomarkers of renal function in children born prematurely in a University Hospital in northeastern Brazil. To this end, two independent studies were developed: a systematic review of the literature and a cohort study. The systematic review included original studies in Portuguese and English languages, published between the years 2014 to 2020 in the bireme, medline and cochrane databases. Data were extracted on the prognostic value of cystatin C for acute kidney injury (AKI) in preterm newborns and the synthesis of the results were analyzed descriptively. In the cohort study, renal function was assessed at birth and follow-up: <3, 4-6 7-24, 25-36 months after birth. Clinical, laboratory and anthropometric characteristics were also considered. Serum creatinine and cystatin C levels were used to assess renal function in addition to the respective estimates of glomerular filtration rate (GFR), obtained by means of equations. The Wilcoxon nonparametric test was used to compare the means of the clinical variables at the different time points, with a significance level of 5%. Sixteen publications remained in the systematic review. Serum cystatin C was indicated as a biomarker superior to serum creatinine with good prognostic value in the early detection of AKI in premature newborns. The presence of adverse conditions at birth did not affect the safety of this marker of preterm renal failure. The results of a cohort study of 105 children evaluated at birth revealed that 54.3% were boys, with mean creatinine levels of 0.71±0.32 and cystatin levels of 1.52±0.32. Regardless of the period of assessment of renal function, the children had elevated serum cystatin C and reduced GFR. Serum creatinine was within normal ranges and respective GFR. When comparing the GFR at birth and follow-up, significant difference was found in the GFR estimated by cystatin in children aged between 7 to 24 months. From both studies, it can be concluded that cystatin C has acceptable prognostic value for predicting AKI in preterm infants. Its reference values for estimating GFR in this population are not sufficiently clarified. The results point out that cystatin C may be more reliable than serum creatinine for detection of altered renal function in infants with premature birth.