Measurement of renal blood flow in human subjects using the ultrasound velocity profiling technique

To (1) assess the accuracy of the ultrasound velocity profiling (USVP) technique of renal blood flow (RBF) measurement in normal subjects and (2) compare renal blood flow measurements obtained using USVP and renal clearance rate in patients with renal diseases.

First, we calculated unilateral renal blood flow (unil-RBF) using USVP and the clearance rate of para-aminohippuric acid (CPAH) simultaneously in six healthy male subjects. We then compared unil-RBFUSVP and unil-RBFPAH in nine patients with chronic glomerulonephritis (CGN).

In the first study, the limits of agreement in a Bland-Altman plot ranged from -325.3 to 32.0 ml/min per 1.48 m(2). The mean bias was -146.7 ml/min per 1.48 m(2). Subdivision for values of unil-RBFUSVP by flow showed small discrepancies in values above 280 ml/min per 1.48 m(2): mean bias, -98.2 ml/min per 1.48 m(2); limits of agreement, -223.3 to 26.8 ml/min per 1.48 m(2). The three patients in the second study had immunoglobulin A (IgA) nephropathy, in whom unil-RBFPAH was estimated as being markedly lower than unil-RBFUSVP, contrary to the primary result.

Despite its consistent negative bias, USVP may be a reliable method of quantifying renal blood flow noninvasively when measured values exceed 280 ml/min per 1.48 m(2). We assumed that the p-aminohippurate extraction rate (EPAH) was profoundly impaired in the three patients with IgA nephropathy.