The influence of aging on renal blood flow in human beings

We studied the relationship between age and renal blood flow parameters to determine the clinical significance of using Doppler color flow imaging (CFI) in their measurement.

One hundred forty-four healthy subjects with no renal or circulatory diseases took part in this study. All subjects were placed in the prone position and examined with CFI. The kidney was visualized in a longitudinal view, and blood flow in the interlobar arteries was studied. Peak systolic flow velocity (Vmax), end-diastolic flow velocity (Vmin), and resistive index (RI) were used as blood flow parameters.

Age and Vmax were not significantly associated (p=0.03) in the interlobar artery. Vmin decreased significantly (p<0.01) with age, while RI increased significantly (p<0.01) with age. No statistically significant sex-related renal blood flow parameters were found.

Ishimura et al have reported that RI was significantly correlated with age in diabetic patients. Here the same result was obtained in healthy subjects. The incidence of arteriosclerosis is known to increase with age. In general, RI is influenced by vascular resistance. Increase in RI with age in this study was explained by the effect of arteriosclerosis on age-related vascular resistance. These results suggest that age should be considered in the study of blood flow in the kidney.