Ultrasonographic assessment of renal size and its correlation with body mass index in adults without known renal disease.

BACKGROUND Many conditions affect renal size. To evaluate abnormalities in renal size, knowledge of standardised values for normal renal dimensions is essential as it shows variability in the values of normal renal size depending on body size, age and ethnicity. Ultrasound, being an easily available, noninvasive, safe and less expensive modality, is widely used for evaluation of renal dimensions and repeated follow-ups. The objectives of this study were to determine renal size by ultrasound in adults without any known renal disease, and to determine the relationship of renal size with body mass index. METHODS Study was conducted in the Department of Diagnostic Radiology, Shifa International Hospital and PIMS Islamabad. Renal size was assessed by ultrasound in 4,035 adult subjects with normal serum creatinine and without any known renal disease, between November 2002 and December 2010. Renal length, width, thickness and volume were obtained and mean renal length and volume were correlated with body mass index and other factors like age, side, gender, weight and height of the subjects. RESULTS Mean renal length on right side was 101.6 +/- 8.9 mm, renal width 42.7 +/- 7.1 mm, and parenchymal thickness 14.4 +/- 2.9 mm. On left side, mean renal length was 102.7 +/- 9.2 mm, width 47.6 +/- 7.0) mm, and parenchymal thickness 15.1 +/- 3.1 mm. Mean renal volume on right was 99.8 +/- 37.2 cm3 and on left was 124.4 +/- 41.3 cm3. Left renal size was significantly larger than right in both genders. Relationship of mean renal length was significant when correlated with age, side, gender, height and weight, and body mass index. Renal volumes also showed a similar relationship with side, gender, height and weight, and body mass index; but with age such a relationship was seen only for left kidney. CONCLUSION Pakistani population has mean renal size smaller than reference values available in international literature. Renal length and volume have a direct relationship with body mass index. Mean renal size is related to the side, age, gender, height and weight as well.