Evaluation of the state of tubular epithelium in low birth weight infants with ischemic ­nephropathy

Aim. The study of the diagnostic value of KIM-1 and NGAL in urine and cystatin C in the blood plasma of low birth weight infants with ischemic nephropathy.

Methods. 150 newborns were divided into 3 groups: main group — 72 low birth weight infants with manifestations of ischemic nephropathy divided into three subgroups: group 1A — mild (n=36), 1B — moderate (n=20), 1C — severe (n=16); comparioson group — 28 low birth weight infants without the evidence of ischemic nephropathy; control group — 50 healthy newborns (20 full-term and 30 preterm).To assess the state of tubular epithelium of the kidneys, the levels of KIM-1 and NGAL were measured in the urine of neonates, to assess the state of glomerular filtration the level of сystatin C in the blood plasma was determined. Samples of blood and urine were collected twice, on days 1 to 3 and 7 to 10. Biomarker levels were determined by solid-phase enzyme immunoassay.

Results. In the main group on day 1 to 3 of life KIM-1 and NGAL in the urine were significantly elevated compared to the control group (p <0.001). On day 7 to 10 the level of KIM-1 in the urine in subgroup 1A decreased (0.98±0.09 ng/dl), while remaining significantly higher compared to the control group, and in subgroups 1B and 1C it increased to 1.24±0.10 and 1.36±0.12 ng/dl, respectively. On day 7 to 10 of life the concentration of NGAL in the urine of children of all three subgroups declined, remaining significantly high compared to the control values. Сoncentration of cystatin C was significantly high only in newborns of subgroup 1C (p <0.001).

Conclusion. Molecules of NGAL and KIM-1 are early markers of the renal ischemic injury in low birth weight infants who suffered perinatal hypoxia, and cystatin C cannot be considered an early predictor of renal damage in low birth weight infants with ischemic nephropathy as its level in the blood rises only in severe damage.