Renal mobility in a clinical patient material submitted for urography.

The clinical entity of increased renal mobility accompanied by typical clinical symptoms is usually referred to as mobile kidney. The renal mobility in a normal population has never been established. The aim of this study was to determine the mobility range of both kidneys, and to evaluate the limits of increased renal mobility and its frequency in a population without symptoms of mobile kidney. In a prospective study, 131 patients referred for urography were examined in the supine and erect positions and the mobility of each kidney was measured on the films. Mobility expressed in lumbar vertebral heights varied from 0 to 2.75 for the right kidney and from 0 to 2.0 for the left kidney. The renal mobility was greater among women than among men, and the degree of renal mobility was significantly correlated to low weight and, among women, also to height. An increased renal mobility was defined as mean + 2 SD. Based on the data from the study population the limit for increased renal mobility was found to be 2.0 vertebral body heights on the right side and 1.75 vertebral body heights on the left side. The frequency of increased renal mobility in the population was 7%. Increased renal mobility was significantly more frequent among women (13%), and on the right side. In conclusion, the renal mobility varied widely and increased renal mobility was frequent in patients without symptoms related to the renal mobility.