The diagnosis of GHD is based on GH stimulation tests. The test of choice is the ITT and a peak GH response of less than 9mU/L is considered diagnostic of GHD. Peak GH values of less than 20mU/L during an ITT are infrequently observed in healthy adults. In hypopituitary patients a peak GH values to the ITT of 9-20 mU/L likely represents a state of partial GHD, or GH insufficiency (GHI). To investigate if patients with GHI have similar features to GHD adults we assessed body composition of patients with GHD (n=30), GHI (n=24), and age & sex matched controls (n=30).
The controls were significantly taller than both patient groups, but there was no difference in weight, BMI, waist(W) or hip(H) measurements. W/Hratio was significantly greater in the GHD, and GHI patients compared with controls (0.885 vs 0.871 vs 0.818; P=0.003). The sum of skinfolds was greater in patients than controls (78.2 vs 80.8 vs 59.6mm; P=0.003). Bioimpedence did not demonstrate a difference in FM between groups, however, LBM was reduced in the GHD & GHI groups compared with controls (42.8 vs 41.9 vs 50.8kg; P=0.026). Whole body DXA confirmed the bioimpedence findings of no significant difference in FM, and reduced LBM in the patient groups (43.8 vs 45.0 vs 50.6kg; P=0.028). %FM was significantly greater in the GHD & GHI patients compared with controls (34.7 vs 31.8 vs 26.5%; P=0.001). DXA truncal FM was greater in the patient groups (11.6 vs 9.6 vs 7.2kg; P=0.012) compared with controls. FM/LBM ratio was greater in the patients than the controls (0.58 vs 0.51 vs 0.40; P=0.001). In keeping with the above findings serum leptin was greater in the patients than the control group (28.0 vs 32.7 vs 18.9; P=0.015).
The impact of GHI on body composition is intermediate to that of GHD adults and healthy control subjects, and demonstrates that lesser degrees of GH deficiency have adverse effects on LBM, FM and fat distribution.
24 - 26 Mar 2003
British Endocrine Societies