Correlation Between Kidney Size and Lean Body Mass in Survivors of Childhood and Young Adult Acute Lymphoblastic Leukemia

ABSTRACT Background Survivors of acute lymphoblastic leukemia (ALL) have reduced lean body mass compared with the general population. In healthy children, an association between lean body mass and kidney size has been reported, while this correlation in ALL survivors remains unexplored. Understanding this correlation is essential when evaluating kidney size during follow‐up. Procedure The study cohort included 240 ALL survivors, diagnosed between ages 1 and 45 years in Denmark between 2008 and 2018, treated according to the NOPHO ALL2008 protocol, and having survived ≥1 year post‐treatment. A control group of 278 individuals from the general population, matched by sex and age, was included. Renal ultrasound and dual‐energy x‐ray absorptiometry scans were performed between 2019 and 2024. Results Median age at study participation was 13 years (range: 5–47) among survivors and 14 years (range: 5–53) among controls. Both female and male survivors had lower lean body mass than controls (females: median 30.3 kg [range: 12.6–55.6] vs. 37.8 kg [range: 15.0–64.2], p ≤ 0.001; males: median 39.3 kg [range: 13.8–74.5] vs. 45.9 kg [range: 15.3–81.2], p = 0.025). Female survivors had smaller total kidney volume than female controls (median 191.2 cm 3 [range: 90.7–341.0] vs. 216.1 cm 3 [range: 94.4–424.5], p = 0.003), while no significant difference was observed in males. Total kidney volume strongly correlated with lean body mass in both survivors and controls, explaining 73% and 65% of the variance in total kidney volume, respectively. Conclusions This study underscores the importance of incorporating body composition measurements when evaluating kidney size in ALL survivors.