be
48
:
PROGRESS IN ATOMIC MEDICINE
5
—
measurement is not available, but which Allen et al. calculates from
measurement of height and inter-condylar dimensions of elbows, knees,
wrists, and ankles.”
Equation 8—divides the lean tissues into muscle and muscle-free lean
(MFL) with different potassium and water contents.*
Body Compartment Systems
Systems of classification of the components of the body have proliferated rapidly and with confusing terminology .{see Table 2). These
systems have had their origin in the measurement of body water alone,
body density alone, a combination of body water and bedy density, a
combination of chemical and anatomical terms and attempts to divide
the body into physiological or functional divisions.’°°° Each has had
separate goals. Perhaps the oldest classification is that of the division of
the body into two compartments, the fat free body mass, consisting of
minerals, proteins, water and a lipid component.’ Various modifications
of the fat free body mass have been made. Behnke added a small amount
of fat which was considered to be essential lipids,'® principally the lipids
of the central nervous system, and to this applied the term “lean body
mass.” There has been a tendency to use interchangeably the terms
“lean body mass” and “‘fat free body mass.” As defined by Behnke, the
difference is small but real. Recently, Moore and colleagues” and
Anderson’ have developed a three compartment system. The “body cell
mass” of Moore et al.’ is a chemically homogeneous mass containing
approximately three milliequivalents of potassium per gram of nitrogen
and consists of tissues that require oxygen, produce CO:, and burn glu-
cose. To this is added a second compartment consisting of extracellular
fluid and supporting tissues. These are tissues that contain much less
potassium. The third compartment is fat.
Anderson* has proposed a somewhat similar division into muscle and
muscle free lean ( MFI.) tissues and fat based upon measurement of
potassium and water content by Forbes and Lewis.*®
There is a continually recurring theme of a reference man***"** which
consists essentially of an ideal person with the mineral. protein, and fat ’
content that would exist in a healthy young male adult. To this framework. adipose tissue is added. Unfortunately adipose tissue, while principally lipid. contains mineral. protein. and water in variable
concentrations.”