Abstract:
The objectives of this study were to compare and make correlations between
age and Doppler parameters of the interlobar arteries, including synchronously obtained
plasma renin and aldosterone levels and to obtain new normative data regarding acceleration
time in healthy children from neonates to 16 years. One hundred sixty-nine healthy children (72 girls and
97 boys) were classified into four groups: group 1 (< 1 year; n = 34), group 2 (range, 1–6 years;
n = 48), group 3 (range, 6–12 years; n = 50), and group 4 (range, 12–16 years; n = 37). Blood
samples from the renin and aldosterone were collected in the morning after bed rest and fasting.
The resistive index (RI), pulsatility index (PI), and the acceleration time of the renal interlobar
arteries with duplex Doppler sonography, including both kidney longitudinal lengths with grayscale
sonography, were evaluated. One-way analysis of variance with the least significant difference
post-hoc test and Pearson’s correlation test were used to compare the differences between
groups and to make correlations, respectively. An independent-sample t test was used to
evaluate the differences between all parameters based on sex and to compare the left and right
kidney longitudinal lengths in each group. The RI, PI, and acceleration time were statistically significant in betweengroup
comparisons. Only in group 4 was acceleration time not statistically significant compared
with groups 2 and 3. Plasma renin levels were significantly higher in group 1 compared
with groups 2 (p < 0.03) and 4 (p < 0.0001); in group 2 compared with group 4 (p < 0.05); and
in group 3 compared with group 4 (p < 0.01). The plasma aldosterone levels were significantly
higher only in group 1 compared with groups 2 (p < 0.001), 3 (p < 0.008), and 4 (p < 0.0001).
The RI correlated linearly with the PI, plasma renin levels, and aldosterone levels and correlated
inversely with acceleration time. Age had a negative correlation with the RI, PI, plasma
renin levels, and aldosterone levels and correlated positively with acceleration time. There were
no statistically significant differences between all parameters based on sex and no significant
difference found between the right and left kidney longitudinal lengths in each group.
The RI in children up to 54 months old is higher than in adults. Therefore,
the adult mean renal RI criterion of 0.70 should be applicable to children 54 months old
and older. We showed that the age dependency of the RI was directly related to that of plasma
renin and aldosterone levels in healthy children in whom Doppler parameters and blood analysis
were evaluated synchronously.
