Progression of serum creatinine and glomerular filtration rate in neonatal critical care patients during the first seven days of life

Background Serum creatinine and estimated glomerular filtration rate (GFR) are key indicators of kidney function. Methods This descriptive, retrospective study included neonatal patients admitted to a tertiary hospital's neonatal intensive care unit from January 2013 to December 2016. Data on kidney function were collected from birth to 7 days of life. Patients were stratified into four gestational age groups: below 28 weeks, 28-31 weeks, 32-36 weeks, and term neonates. Qualitative variables were expressed as percentages. Quantitative variables were assessed using the Kruskal-Wallis/Wilcoxon tests. Chi-square analysis was performed for categorical variables. Statistical analysis was conducted using SPSS (Version 22.0), with significance set at p < 0.05. Results Among 138 patients, 99 (71.7%) were premature. Term neonates showed a gradual postnatal decline in creatinine, while premature infants exhibited an initial rise followed by a decline, with values inversely proportional to gestational age (at seven days: 0.70 +/- 0.19 mg/dL in below 28 weeks vs. 0.39 +/- 0.08 mg/dL in term, p < 0.001). Among the clinical-epidemiological variables of the included patients, seven significantly influenced serum creatinine. GFR decreased in premature neonates at 24 h, then increased throughout the study. Term neonates demonstrated a progressive GFR increase, with higher values associated with greater gestational age (at seven days:16.8 +/- 5.0 ml/min/1.73m(2) in below 28 weeks vs. 41.8 +/- 8.0 ml/min/1.73m(2) in term, p < 0.001). Conclusions Evaluating kidney function in neonates, based on serum creatinine and GFR, requires special attention during the first days of life, particularly in critically ill neonates due to multiple physiological changes and clinical factors that may influence these parameters.