OBJECTIVE: Measurement of kidney size by ultrasonography is an important parameter in the renal evaluation of patients. This study aims to establish the average size of kidneys of healthy adult Filipinos and examine the factors that influence it.
DESIGN: Cross-sectional, observational study
SETTING: Section of Nephrology, Department of Medicine and Department of Radiology, UP-PGH Medical Center, a tertiary government hospital
PARTICIPANTS: 264 healthy Filipino adults underwent kidney ultrasound after preliminary screening by history, physical examination, urinalysis, and serum creatinine
RESULTS: Renal sizes and volume were measured by ultrasound in 105 males and 159 females, with ages ranging from 18 to 75 years old. The left kidney was significantly larger than the right for mean length but not for width or thickness. Except for cortical thickness, renal length (L=98 mm, R=96mm vs. L=95mm, R=93mm), width (L=48mm, R=49mmvs. L=46mm,R=46mm), and thickness (L=43mm, R=42 mm vs. L=39 mm, R=39 mm) were significantly larger in males compared to females. While the gender differences persisted when corrected for age and body mass index, this disappeared when corrected for total body area. With advancing age, there was minimal shortening but significant increases in width and thickness (renal shape index)
CONCLUSION: Our study provides estimates of the average kidney size for normal adult Filipinos. The average kidney size of Filipinos is smaller than that of Caucasians for length (L=96mm vs. 112 mm, R=94mm vs. 109mm) and for width (L=47mm vs. 58mm, R=48mm vs. 57mm). Males have larger kidneys than females but the gender difference disappeared when corrected for total body area. Height but not weight has a significant influence on kidney size. With advancing age, kidneys tend to increase in width and thickness with no significant decrease in length or volume.