Blood volume and age: repeated measurements on normal men after 17 years.

Blood volume and age: repeated measurements on normal men after 17 yam. J. Applied Physiol. 2 I (2) : 583-588. I g66.-Plasma volume was determined with ‘I-1824 in 41 male subjects (average age 41) and compared with the results obtained on the same subjects 16-17 years ago. In more than two-thirds of the subjects, plasma volumes measured 16-17 years apart agreed within 5 % and the mean plasma volume of the group remained constant. Since the hematocrit and serum protein concentration also showed no significant changes, the cal-culated blood volume, cell volume, and total serum protein all remained essentially unchanged. Since there was a mean gain in weight of approximately I o%, the volume measurements expressed as milliliters per kilogram weight showed an average decrease by about I 0%. Volume measurements expressed as milliliters per square meter surface area also decreased slightly.