A comparative study of methods of estimating kidney length in kidney transplantation donors

Knowledge of kidney size is important for clinical assessment of renal disease. However, there are few studies on methods of assessing kidney size. The purpose of this study was to determine the usefulness of body index and radiological measurements for prediction of kidney size.

One hundred and twenty five donors were enrolled. The sizes of donor kidneys obtained after nephrectomies for kidney transplantations were documented and the correlation coefficient between kidney length and body index was calculated. Kidney length was estimated from the distance between the first and third lumbar vertebrae (L1-3), intravenous pyelograms (IVPs), abdominal ultrasonography (US), and abdominal computed tomography (CT).

Normal adult kidneys were 11.08 +/- 0.96 cm long, 6.25 +/- 0.67 cm wide, 4.73 +/- 0.65 cm thick and weighed 196.3 +/- 41.0 g. Correlation coefficients between kidney length and body height, body weight, body surface area and total body water content were 0.29, 0.31, 0.26, and 0.32, respectively. The difference between actual and predicted kidney lengths was -0.6 cm for L1-3, +1.2 cm for IVPs, -0.7 cm for abdominal US, -0.8 cm for transverse CT section, and -0.5 cm for coronal CT section.

Abdominal coronal CT section predicted kidney length more accurately than other radiological methods, but all radiological methods were associated with prediction errors. As kidney length was correlated with body index, it is suggested that body index is the most useful and simplest method of estimating kidney size as an adjunct to treatment decisions concerning renal disease.