Sonographic Evaluation of the Morphology of Kidneys Among Apparently Healthy Children in Northwest Ethiopia, 2021: The Normal Limits and Percentile Curves

BACKGROUND: Establishing a customized reference chart and curve of renal size for a specific population of the same sociodemographic characteristics enables a better interpretation of sonographic assessments. OBJECTIVE: To evaluate the morphology of kidneys using ultrasound and establish the normal limits and percentile curves among apparently healthy children in northwest Ethiopia, 2021. DESIGN: A hospital-based cross-sectional study design. SETTING: The study was conducted in Debre Markos comprehensive specialized hospital, Finote Selam general hospital, and Bichena primary hospitals. PATIENTS: The study participants were 403 apparently healthy school-age children, from December 2019 to June 2020. METHODS: Data were collected using a structured questionnaire, physical examination, and ultrasound. We used EPI-Data Version 3.1 for data entry. Height and body surface area–related kidney length and volume curves and tables were generated after lambda-mu-sigma (LMS) quantile regression with a Box-Cox Transformation to Normality using the vector generalized additive model (VGAM) method and generalized additive model for location, scale and shape (GAMLSS) (R, VGAM, and GAMLSS package). RESULTS: The height and body surface area of children was the best predictor of the sonographic dimensions of the kidneys. Reference intervals were established using height and body surface area specific for clinically practical dimensions of the kidney (length and volume). LIMITATIONS: Calibration of measuring tools in the hospitals was not conducted frequently; community fatigue due to presence of many research projects in the selected hospitals was observed. CONCLUSIONS: According to this study, the children are considered to have normal sonographic dimensions if ultrasound values lie between the 2.5th and 97.5th percentile based on their respective height and body surface area.