Estimation of renal size from radiographs: is the effort worthwhile?

The weight of renal substance was measured in normal kidneys obtained at necropsy after removal of fat from the renal sinuses. This fat fo-med an average of 5 percent of the total renal weight, increasing only slightly with age. The weight of renal substance was correlated with measurements of length, width, depth and area obtained from radiographs. The best estimate of renal weight was made by using length alone. The effect of rotation of the kidney on its radiographic dimensions was also assessed. At the angles at which kidneys lie in the body, the longitudinal dimensions are less affected by small changes in rotation than the transverse dimensions. However, rotation within the range of arc normally found in the body may cause apparent diminution length of 1 cm or more.