BODY-COMPOSITION ANALYSIS BY DUAL-ENERGY X-RAY ABSORPTIOMETRY AND ANTHROPOMETRY IN ADULTS WITH CHILDHOOD-ONSET GROWTH-HORMONE (GH) DEFICIENCY BEFORE AND AFTER 6 MONTHS OF RECOMBINANT GH THERAPY

Measurements of total body fat (BF) and fat free mass (FFM) obtained b y anthropometry, using the Durnin and Womersley (DW) equations, and by total body dual energy x-ray absorptiometry (DXA) were compared in 8 adults with childhood-onset GH deficiency (GHD) and in 9 healthy subje cts. The sensitivity of these two methods in detecting the changes in body composition produced by six months of GH therapy in patients with GHD was also compared. Anthropometric determination of percent BF was calculated from the sum of biceps, triceps, subscapular and suprailia c skinfolds, using the appropriate DW and Siri equations for body dens ity and percent fat estimation, FFM was calculated by subtracting BF f rom body mass (BM). BF and FFM were also determined by DXA (QDR 1000\W , Hologic Inc), The data obtained from the GHD patients were compared with those recorded in a control group of healthy males, matched for s ex, age and physical activity. Body composition obtained by anthropome try: before GH treatment, significant differences existed between pati ents and controls in terms of BM (mean +/- SD: 45.8 +/- 10.0 vs 71.7 /- 6.6 kg), percent BF (21.0 +/- 3.2 vs 17.1 +/- 3.7%) and FFM (36.0 /- 6.5 vs 59.3 +/- 3.7 kg), while body mass index (BMI, kg/m(2)) value s were similar in the two groups. Six months of GH therapy did not cha nge BM and BMI, but caused a significant reduction of percent BF (from 21.0 +/- 3.2 to 18.6 +/- 4.0%) and a rise of FFM (from 36.0 +/- 6.5 t o 38.0 +/- 6.7 kg). After treatment, no significant differences were f ound between percent BF values of patients and controls, Body composit ion obtained by DXA: BF (22.0 +/- 3.9%) and FFM (37.2 +/- 8.0 kg) of p atients significantly differed from those of controls (16.8 +/- 3.7% a nd 59.8 +/- 3.7 kg) before treatment; after GH treatment, percent BF v alues (17.7 +/- 4.9%) of patients were similar to those of controls. A nthropometry vs DXA: high correlation (p<0.001-0.0001, R-2 = 0.784-0.9 88) was found between the percent BF and FFM determined by anthropomet ry and by DXA for both patients, before and after treatment, and contr ols, It is noteworthy that, for both BF and FFM, most values were even ly distributed along the identity line, showing no systematic overesti mation or underestimation by anthropometry. The relation between DXA a nd anthropometry was maintained even after GH treatment. These results indicate that body fat: and FFM assessment by anthropometry are compa rable to those by DXA. GH-induced changes in body composition in hypop ituitary adults are detected with the same level of accuracy by the tw o techniques. The reliability, practicality and low cost of anthropome try favour its use for the assessment of body composition even in GHD patients. (C) 1997, Editrice Kurtis.