Sonographic Measurement of Absolute and Relative Renal Lengths in Southeast Nigerian Adults

Abstract

The objective of this study was to evaluate sonographically measured absolute and relative lengths of normal kidneys according to subject height, sex and age. Real time sonography was perfumed on 310 subjects (135 men and 175 women) without renal impairment. Measurements of longitudinal renal diameter represented absolute renal length (ARL). Relative renal length was calculated using the kidney length: body height ratio (KBR). The subjects’ ages ranged from 18 to 80 years (mean = 38+10.6). The mean height of the subjects were 167+8cm for men and 160+8cm for women. The left kidney was absolute and relatively longer than the right kidney, regardless of sex (P< 0.001). The mean ARL was significantly greater in men than in women for both kidneys (P< 0.05), but there was no significant difference between the mean KBRs (P>0.05). Renal length decreased with age, peaked at the 4th decade of life and the rate of decrease seemed to accelerate after 50 years of age. Sex was not a significant predictor of renal length when height and age were included in the multivariate regression analysis. Results suggest that relative renal length better represents kidney size than absolute renal length because it eliminates sex and height differences.