Clinical relevance of plasma cystatin C in the diagnosis of acute kidney injury in preterm infants

BACKGROUND: Acute kidney injury is one of the most common syndromes in premature neonates requiring treatment in intensive care units. Early diagnosis of acute kidney injury in these patients is extremely difficult due to lack of specific signs, morphofunctional immaturity, low sensitivity and specificity of renal dysfunction markers. AIM: The aim of the study is to assess the clinical significance of plasma cystatin C concentration in the diagnosis of acute kidney injury in premature newborns in the early neonatal period. MATERIALS AND METHODS: The design was a primary, prospective, non-randomised study including 100 preterm neonates with gestational age less than 37 weeks and birth weight up to 1500 g. Indicators of renal functional status (creatinine, diuresis rate, cystatin C) were assessed on the first, third and seventh days of life. RESULTS: Low birth weight (p = 0.001; OR = 0.226), the need for invasive control mechanical ventilation (p = 0.012; OR = 6.32) and inotropic therapy (p = 0.025; OR = 4.99) are associated with a high risk of acute kidney injury development. A direct correlation was found between the presence of acute kidney injury, plasma creatinine (p = 0.001, r = 0.688) and cystatin C (p = 0.001, r = 0.689) levels. The first increase in plasma creatinine levels relative to basal levels in preterm neonates with acute kidney injury was noted from the third day of life, which was statistically significant compared to those of children without acute kidney injury (91.0 vs 57.0 mmol/l; p 0.001). The concentration of cystatin C in patients with acute kidney injury is increased from the first day of life (1.85 vs 1.57 ng/ml) and continues to steadily increase by the seventh day of life (2.27 vs 1.84 ng/ml; p 0.001). CONCLUSIONS: Increased concentration of cystatin C in preterm neonates with acute kidney injury is observed from the first day of life and increases in dynamics, which allows us to consider it a highly sensitive and significant marker of renal dysfunction in the early neonatal period.