A multivariable assessment of renal size and growth of scarred kidneys in children

Purpose: We applied a recently developed multivariable renal size nomogram to sonographic measurements of kidneys with known scarring to assess systematically their sizes and growth patterns compared to normal kidneys. Materials and Methods: We retrospectively reviewed renal sonograms of 138 kidneys (55 right and 83 left) with known scarring. The sizes of these scarred kidneys were compared to the 95% prediction limits calculated according to the multivariable renal size nomogram, adjusting for patient age, gender, race, weight and height. The growth of scarred kidneys was evaluated by fitting individual linear regression lines using serial sonographic measurements and comparing the results with normal predicted values. Results: The sizes of 89.1% of the right and 81.9% of the left scarred kidneys were within the 95% normal prediction limits. Only 17 of 138 of the scarred renal units showed smaller kidney sizes compared to the normal prediction limits. Serial sonographic measurements revealed that compared to normal predicted values, 24 of 60 left and 16 of 38 right scarred kidneys grew within ± 1.0% annually of the boundaries of normal predicted values. Additionally, 8 left and 7 right scarred kidneys indicated a growth rate of more than 1% annually higher than the normal predicted values. Conclusions: Multivariable analyses of renal sonographic measurements provided a dynamic picture of kidney well-being in children with renal scarring. We found that the majority of scarred kidneys were within the normal predicted limits, and a large proportion of these kidneys grew equally well compared to those with normal anatomy.