Comparison of methods to estimate body fat in growth hormone deficient adults.
OBJECTIVE
All of the presently used methods for in-vivo determination of body composition have inherent methodological errors and depend on various assumptions. We have therefore compared several different methods used to measure body fat in adult GH deficiency during GH treatment.


METHODS
Comparison of body composition data from a two-phase trial with an initial placebo-controlled, double-blind 6-month period, followed by open treatment with GH until all patients had received GH for 12 months.


METHODS
Twenty-five patients with known GH deficiency entered the study. Baseline examinations were complete in 23 patients, and 22 patients (16 males, 6 females) completed all examinations after treatment.


METHODS
Body fat calculated from total body potassium (TBK) by whole-body 40K counting, total body water (TBW) by tritium dilution, total body nitrogen (TBN) by neutron activation, and bioelectric impedance (BIA) measurements were compared to body fat determinations by dual-energy X-ray absorptiometry (DEXA) in two-compartment and multicompartment body composition models.


RESULTS
At baseline, DEXA fat mass agreed well at group level with measurements based on TBW or TBK alone, in a four-compartment model based on TBK and TBW, and a multicompartment model based on bone mineral (by DEXA), TBN and TBW. Body fat by BIA agreed less well. After 12 months of GH treatment, body fat decreased by all methods used. This decrease was smaller by DEXA than by the other methods. The four-compartment model based on TBK and TBW, and TBW alone, showed the best agreement with changes in DEXA fat.


CONCLUSIONS
All methods showed a decrease of body fat with GH treatment, but variation between methods was considerable.
Bosaeus
I
I
Department of Clinical Nutrition, Sahlgrenska University Hospital, Göteborg, Sweden.
Johannsson
G
G
Rosén
T
T
Hallgren
P
P
Tölli
J
J
Sjöström
L
L
Bengtsson
B A
BA
D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D001823:Body Composition; D001834:Body Water / Q000737:chemistry; D017097:Electric Impedance; D005260:Female; D013006:Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009501:Neutron Activation Analysis; D009584:Nitrogen / Q000032:analysis; D011188:Potassium / Q000032:analysis; D011197:Potassium Radioisotopes; D013997:Time Factors; D014915:Whole-Body Counting
D011197:Potassium Radioisotopes; D013006:Growth Hormone; D009584:Nitrogen; D011188:Potassium