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Total body water (TBW) was determined on 35 subjects with a tritium (HTO) and an ethanol (ETH) dilution method, the latter using breath analyses for blood ethanol content. Lean body mass (LBM) was estimated by hydrostatic weighing. Mean values for water fraction (TBW/wt) were 0.618 +/- 0.05 with HTO and 0.603 +/- 0.06 with ETH. The difference was not significant. The correlation between the two methods was highly significant (r = 0.90, SEE = 3.5 liters, P less than 0.0001). High correlations were also found between TBW and LBM with either method for TBW (r = 0.94 with HTO, r = 0.91 with ETH). Mean values for TBW/LBM were 0.735 with HTO and 0.717 with ETH. The ETH method compares favorably with the HTO, it has the advantage that it is nonradioactive and can be repeated daily if necessary.

Noninvasive characterization of renal artery blood flow variables in the human has not been reported. Using a unique dual-frequency real-time two-dimensional echo Doppler (Duplex scanner) that was calibrated in vitro, we characterized renal artery blood flow patterns in 16 normal subjects (6 females). Calculated mean values of systolic diameter (Ds), maximal spatial average blood velocity (Vmsa), and volume flow rate (Q) were as follows: 4.5 +/- 0.6 mm right, 4.4 +/- 0.6 mm left; 67.6 +/- 9.4 cm . sec-1 right, 69.6 +/- 12.0 cm . sec-1 left; and 403 +/- 127 ml . min-1 right, 395 +/- 98 ml . min-1 left; respectively. Direct linear regression correlation of body surface area (BSA) with Ds and Q were statistically significant (P less than 0.01, r = 0.70; and P less than 0.01, r = 0.72, respectively). In a blind prospective series, six of seven angiographically normal renal arteries were noninvasively identified by normal geometry and blood velocity patterns. One angiographically normal artery was incorrectly classified as mildly stenotic. Eleven angiographically documented abnormal renal arteries were noninvasively identified by their abnormal blood flow patterns and/or geometry. This study suggests that dual-frequency Duplex scanning with careful sample volume control and Doppler audio spectra/blood velocity waveform analysis can be used to characterize blood flow variables in normal and diseased human renal arteries.

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