Kidney Dimensions and its Correlation with Anthropometric Parameters in Healthy North Indian Adults.

Background: Knowledge of kidney size is important in the assessment of kidney function. Changes in kidney size can occur in various kidney diseases due to different causes, hence knowledge of normal kidney dimensions in a population is crucial for diagnosis, follow-up and prognostication. While data from other parts of the world does not apply to the Indian population due to differences in ethnicity, diet and body sizes, and there is also a lack of standardized data on normal kidney sizes in healthy Indian adults.

Materials and methods: Kidney dimensions from 600 healthy adult volunteers ranging between 20 and 70 years of age were measured with sonography by a single radiologist. Differences in dimensions between men and women, and right and left kidney were analyzed. Finally, kidney sizes were correlated with anthropometric variables such as weight, age, body surface area (BSA), height and body mass index. Estimated glomerular filtration rate (eGFR) was correlated with kidney length and renal parenchymal volume (RPV).

Results: The mean kidney length of the whole cohort, irrespective of gender was found to be 9.6 ± 0.7 cm on the right and 9.9 ± 0.7 cm on the left. Mean kidney length in males was significantly more as compared to females on both sides. Both the kidney length and RPV were significantly associated with BSA, weight and height (in that order) in females, whereas in males, kidney length and RPV best correlated with height, BSA and weight (in that order). In both sexes, there was a significant negative correlation between age and kidney length, RPV. eGFR had a significant positive correlation with kidney length and RPV in the cohort.

Conclusion: Normal sonographic mean kidney length was 9.6±0.7 cm and 9.9±0.7 cm on the right and left sides respectively in healthy North Indian population, with the left kidney being larger than the right in all dimensions (length, width, thickness and RPV). Kidney sizes in males were found to be larger than females. Correlation with anthropometric parameters in our study, emphasizes the need to give due consideration to normal variations in kidney sizes with age, gender, height, weight and BSA to differentiate between a normal and a pathologically small or large kidney.