Objective: Our purpose was to demonstrate reduced blood volume in preeclampsia compared with nonproteinuric gestational hypertension and normal pregnancy by use of independent measures of red blood cell and plasma volumes.
Study design: Red blood cells labeled with a nonradioactive stable isotope of chromium and Evans' blue were infused in subjects with preeclampsia or gestational hypertension and normotensive pregnant controls. Blood was sampled eight times over 60 minutes for dye concentration and at 30 minutes for chromium analysis.
Results: Total blood and plasma volumes are decreased in preeclampsia (2660 +/- 382 mL/m2 and 1790 +/- 332 mL/m2, respectively) compared with normotensive subjects (3217 +/- 391 mL/m2, P < 0.001 and 2279 +/- 325 mL/m2, P < .001) and gestational hypertension (3139 +/- 272 mL/m2, P < .001 and 2132 +/- 265 mL/m2, P = .003). Total body/peripheral hematocrit ratio is increased in preeclampsia.
Conclusions: Blood volume, by measurement of red blood cell and plasma volumes, is reduced and has altered distribution in preeclampsia but is normal in gestational hypertension.