Cystatin C as an indicator of the functional state of the kidneys in young children

Introduction. Currently widely adopted benchmarks of normal levels of cystatin in blood and of GFR based on those levels in young children are non-existent. Objective: to determine the content of cystatin C in the blood and the glomerular filtration rate based on it in young children. Materials and methods. Two hundred thirty seven infants aged up 3 years without kidney diseases were examined and divided into subgroups by age, degree of maturity and birth weight. The serum cystatin C was studied by enzyme-immunoassay, GFR was calculated according to Larsson’s formula. Results. Normal levels of serum cystatin C and GFR levels were determined in young children with Larsson’s formula. The dependency of the serum level of cystatin C and GFR calculated on the basis of the age of the infant was proved. The serum cystatin C level depends on the degree of prematurity and body weight at birth. The level of GFR was not influenced by the degree of prematurity, however, infants born with extremely low body weight exhibited lower GFR levels in comparison to those born with normal body weight. Conclusion. The obtained serum cystatin C levels are deemed as normal for young children - full-term infants and those with varying degrees of prematurity.