Estimated lean body mass as an index for normalization of body fluid volumes in humans.

Blood volume was measured in 66 healthy subjects (38 males, 28 females), and extracellular fluid volume in 54 subjects (31 males, 23 females). Volumes were normalized against body weight, height, body surface area, leanness index, and lean body mass (estimated from body weight and height). The regression lines of body fluid volumes against lean body mass passed through the origin on extrapolation and were not different for males and females. None of the other indices fulfilled these criteria. It is concluded that estimated lean body mass is a suitable index for normalization of body fluid volumes. A single set of normal reference values can be used for males and females.