Sonographic assessment of normal kidney dimensions in the first year of life—a study of 992 healthy infants

The omission of standards for renal length in infants younger than 1 year may result in a statistically significant increase in the frequency of “spurious” nephromegaly. Nonetheless, there are only a few reports specifically dealing with normal kidney dimensions in infants. Based on sonographic assessments performed on a sample of 992 healthy infants, between January 2002 and December 2004, this paper sets up standards for normal kidney dimensions in children aged 0–3 months, 3–6 months, 6–9 months, and 9–12 months and establishes correlations between kidney dimensions (length, width, and volume) and body length and weight. Linear as well as non-linear nomograms, with percentiles for all the kidney variables examined, based on body length, are provided. Also, statistically significant differences in mean values (P = 0.000) for all the observed neonatal kidney parameters, depending on gestational age at birth, are demonstrated. Principal advantages of our nomograms are that they are based on a large number of examined healthy infants and that kidney dimensions are related to body length. In addition, subjects are divided into four sub-annual age groups demonstrating gender-related differences in renal growth dynamics. Our linear nomograms are easier to use for routine clinical practice, but the percentile-based non-linear nomograms we present cover a much wider range of variations in normal infant kidney dimensions.