Abstract
Many renal disorders are associated with changes in the size of the kidneys. Ultrasonography has widely replaced the intravenous urogram to evaluate kidney size in children suspected of having urinary tract abnormalities. We examined the kidney length (KL) of 195 children, 105 boys and 90 girls, aged 1 month-15.7 years, without urinary tract abnormalities. Here, we discuss the correlation between KL and age, height, and the distance between the 4th and 5th spinous processes of the lumbar vertebrae (lumbar segment L4-L5). KL showed a linear correlation with these somatic parameters. We noted a mean KL increase of 4.8 mm in boys and 4.6 mm in girls per 10 cm increase in height. The differences between the slopes of the regression lines for the lengths of both the right and left kidneys were also similar. The increase in KL was greater during the first 2 years of life, which mirrors the accelerated body growth during infancy. KL was generally 4-6 times longer than lumbar segment L4-L5. Only 0.5% of the girls, but none of the boys, showed a size that was less than 3.5 times the lumbar segment. We propose the use of the ratio of KL to lumbar segment L4-L5 to evaluate the kidney size as these values are readily available and are simpler to use than any other somatic parameter.
