Urographic percentile charts for vertical kidney mobility in childhood.

Vertical kidney mobility was measured in excretory urograms in 492 children of both sexes, 1 to 16 years of age. The positions of the lower poles of the kidneys were compared in radiographs taken in recumbent and erect children. The mean values and standard deviations of the mobility were calculated (in mm) in 15 one-year-age subgroups, body weight subgroups (intersubgroup difference = 5 kg) and in the lumbar segment L1-L4 length subgroups (intersubgroup difference = 5 mm), establishing the limiting values including 3, 10, 25, 50, 75, 90 and 97% of the studied population of boys and girls. It was found that in the group aged 15-16 years, the mobility of the right kidney was greater than that of the left kidney both in boys and girls. With increasing body weight the mobility of both kidneys corresponding to the 97th centile increased in boys, while in girls the mobility of the right kidney decreased when the body weight of 60-70 kg was reached, and that of the left kidney decreased after reaching 50-60 kg. In boys with the increase in length of the lumbar segment L1-L4, the mobility values corresponding to the 97th centile were markedly increased. The obtained percentile charts of vertical kidney mobility in children will be useful when nephropexy is to be performed.