title: Biological homogeneity and precision of measurement: the boundary conditions for normal in body composition.
abstract: For compartments most urgently important to clinical medicine we have satisfactory levels of measurement precision, and the clinical considerations now are the availability of the methods, and the collection of data for normal subjects. Our colleagues in physics and imaging will improve measurement precisions, but the work most needed is to refine the biological side of the measurement equation. Large numbers of measurements, carefully done with carefully calibrated and unchanging systems, exist only for the special case of measuring body calcium in women, in the large cohort of approximately 2,500 women, studied by Aloia and Cohn with neutron activation, and for body potassium, in these women, and in the larger numbers of diverse age, sex, race, and size in the Rosetta study in our laboratory. Can we benefit from the "orthogonal measurements" and "orthogonal physiologic constraints" approaches, in which triangulation is used to combine measurements from several techniques to establish upper-lower bounds estimates by different techniques, with convergence on a "best fit" result? We have noted that the intrinsic homeostatic mechanisms of the body function with great precision to control body temperature, osmotic and ionic concentrations in the water phase, hypertrophy of muscle with exercise, and remodeling of bone by stress. We consider it unlikely that the control mechanisms are more loosely hinged for such secondary parameters as K/FFM and bone density.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Center for Research in Clinical Nutrition, St. Luke's-Roosevelt Hospital, Columbia University, New York, NY 10025.
authors.forename: R N
authors.initials: RN
authors.lastname: Pierson
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J C
authors.initials: JC
authors.lastname: Thornton
authors.forename: M A
authors.initials: MA
authors.lastname: Russell
authors.forename: S B
authors.initials: SB
authors.lastname: Heymsfield
authors.forename: M
authors.initials: M
authors.lastname: Mazariegos
authors.forename: R M
authors.initials: RM
authors.lastname: Ma
authors.forename: D A
authors.initials: DA
authors.lastname: Weber
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D001823:Body Composition; D001825:Body Fluid Compartments; D001834:Body Water / Q000737:chemistry; D015519:Bone Density; D005110:Extracellular Space / Q000737:chemistry; D005260:Female; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry; D009501:Neutron Activation Analysis; D011506:Proteins / Q000737:chemistry; D012016:Reference Values
chemical_list: D011506:Proteins