Age, Sex, and Laterality-Based Evaluation of Renal Volume and Surface Area Using CT-Based Three-Dimensional Segmentation

Background: The kidneys maintain systemic homeostasis, making renal size assessment essential for evaluating various disorders. Renal volume represents a critical morphometric parameter with distinct clinical significance. This study investigated age-, sex-, and laterality-related differences in renal volume and surface area within an adult population. Methods: A total of 582 kidneys from 291 individuals aged 19 to 89 who underwent abdominal CT scans were retrospectively examined. The images were imported into the 3D Slicer software (version 5.6.2) in DICOM format, and automatic segmentation was performed using the Total Segmentator module. The volumes and surface areas of both kidneys were measured and compared according to age and sex groups. Results: Kidney volume and surface area values were found to be significantly higher in men than in women (p < 0.05). This difference was particularly pronounced in the 30–69 age range. The highest volume values were found in women in the 40–49 age group, while in men, they were found in the 30–59 age group. However, in groups over seventy years old, the gender difference lost its statistical significance. Additionally, the left kidney was found to be significantly larger than the right kidney (p < 0.05). As age increases, a gradual decrease in kidney volume and surface area is observed in both sexes. Conclusions: The progressive decline in renal metrics and the disappearance of sex-based differences after 70 years align with age-related parenchymal atrophy, nephron loss, and reduced blood flow. These findings support the establishment of data baselines for clinical monitoring and surgical planning.