Sonographic Measurement of Renal Dimensions in Adults and its Correlates

Background: Unilateral or bilateral changes in kidney size are manifested by many renal diseases and to recognize these anatomical deviations, it is important to have standard sonographic measurements for appropriate comparison. Our primary aim was to determine a normal range of values for renal dimensions in our asymptomatic adult population and to correlate renal length with measures of renal function as a secondary objective. Methods: A cross-sectional population survey was conducted at two spaced-out densely populated areas in the city of Karachi, Pakistan. Ultrasound was preformed and blood samples collected from 225 healthy individuals with no known renal pathology and with normal calculated GFR. Results: Mean kidney lengths were 9.85cm (95% CI: 9.74-9.95 cm) on right side and 10.0 cm (9.85-10.1 cm) on left. The mean width was 4.61cm (95%CI: 4.53 – 4.68cm), cortical thickness 1.46 cm (CI 1.43-1.49cm) with estimated average kidney volume 35.7 cm3 (CI: 34.1-36.5 cm3). Males had larger kidney sizes than females (p < 0.001); age however was only associated with a decrease in renal length after ages 70 and above.(p=0.001) Renal length best correlated with body weight (correlation coefficient 0.384) .eGFR, representative of renal function also positively correlated with renal length (Coefficient 0.415). A multivariate analysis showed male gender (OR 1.60), age (OR 0.89), weight (OR 1.02) and height (OR 7.77) to be significant independent predictors of renal length. Conclusion: We established the normal values for renal dimensions in our adult population. Our study signifies the potential of ultrasound as a useful tool for diagnostic and follow-up purposes of kidney–associated diseases. By extending this research and including data from other parts of the country; we can formulate a gender and age specific nomogram for kidney dimensions for adequate comparison in evaluation of kidney diseases.