Plasma and interstitial fluid volume in extensive skin disease.

Plasma volume and extracellular fluid volume were determined simultaneously in 17 patients with extensive skin disease and 18 matched normal subjects after an intravenous bolus injection of 131I-labeled human serum albumin and inulin. The patients had a decrease in plasma volume (-6%), which, however, was statistically significant only when related tao body weight or surface area. There was a concomitant increase in extracellular fluid volume (+7%) and interstitial fluid volume (+12%). These deviations from control data were statistically significant neither in absolute values nor when related to body size. Interstitial fluid volume was calculated as the difference between extracellular fluid volume and plasma volume. The mean plasma volume: interstitial fluid volume ratio was significantly lower in the patients (0.35 +/- 0.05 SD) than in the control group (0.42 +/0 0.05 SD) (p < 0.001). These results show that a shift of fluid from the intra- to the extracellular spaces is present in patients with extensive skin disease. Elevated microvascular water filtration in the skin is suggested as a major mechanism of this abnormal fluid distribution.