SONOGRAPHIC MEASUREMENT OF ABSOLUTE AND RELATIVE RENAL LENGTH IN ADULTS

Purpose. The aim of this study was to evaluate sonographically measure d absolute and relative lengths of normal kidneys according to subject height, sex, and age. Methods. Real-time sonography was performed on 202 subjects. Measurements of longitudinal renal diameter represented absolute renal length. Relative renal length was calculated using the kidney length: body height ratio (KBR). Results. Statistical analyses were done on findings in 175 subjects without renal impairment (104 me n and 71 women) whose ages ranged from 17 to 85 years (mean +/- SD, 46 .3 +/- 17.1). The mean heights of the subjects were 176 +/- 7 cm for m en and 167 +/- 6 cm for women. The left kidney was absolutely (mean +/ - SD, 112 +/- 9 mm) and relatively (mean KBR +/- SD, 0.655 +/- 0.042) longer than the right kidney (absolute length, 110 +/- 8 mm; KBR, 0.64 1 +/- 0.038), regardless of sex (p < 0.01). The absolute renal length was significantly greater in men than in women for both kidneys (p < 0 .01), but there was no significant difference between KBRs (p > 0.05). Renal length decreased with age, and the rate of decrease seemed to a ccelerate at 60 years and older. When height and age were included in the multivariate regression analysis, sex was not a significant predic tor of kidney length. Conclusions. Relative renal length better repres ents kidney size than absolute renal length because it eliminates sex and height differences. (C) 1998 John Wiley & Sons, Inc.