Sonographic measurements for kidney length in normal Saudi children: correlation with other body parameters

BACKGROUND: Ultrasonography provides a quick assessment of visceral organ dimensions without any risk of radiation. Since many diseases can affect the kidney size, having a reliable reference for kidney length in children is valuable for clinical assessment. OBJECTIVE: Establish normal growth curves for renal length in relation to sex, age, body weight, height, body mass index and body surface area of healthy children in Saudi Arabia. DESIGN: Retrospective review of ultrasonography images. SETTING: Tertiary referral hospital. PATIENTS AND METHODS: We included all normal ultrasonography exams of renal length from full-term neonates to children ≤14 years old performed between 2003 and 2018. Data was collected retrospectively from the electronic archive and patient records. MAIN OUTCOME MEASURES: Relationship between the longitudinal length of both kidneys and age, height, weight, body mass index and body surface area. SAMPLE SIZE: 950 patients. RESULTS: The left kidneys were longer than the right kidneys (P<.001). Height had the most significant correlation with kidney length (R(2)=0.829, P<.001 for right kidney; R(2)=0.831,P<.001 for left kidney). There was a consistent difference in kidney length by sex. Both kidneys were longer in males than females (P=.031, right kidney:, P=.015, left kidney). In terms of renal growth by age, our data showed a statistically significant difference before and after 24 months of age. There was no significant difference between populations from Saudi Arabia, Hong Kong (P=.485) and Australia (P=.99), but the difference between Saudi and American children was significant (P<.001). However, we did not have the data from those studies for direct comparison. The correlation plots of renal length versus age for all four countries were similar. CONCLUSION: The tables and correlation plots generated from this study should be useful to radiology departments in assessing conditions in children ≤14 years of age that lead to changes in renal size. LIMITATIONS: Retrospective, and there were differences in ultrasonographic techniques for patient positioning and cursor placement that can affect the reproducibility of measurements of renal length. CONFLICT OF INTEREST: None.