SERUM INSULIN-LIKE GROWTH-FACTOR-I (IGF-I), IGF-BINDING PROTEIN-1 ANDPROTEIN-3, AND THE ACID-LABILE SUBUNIT AS SERUM MARKERS OF BODY-COMPOSITION DURING GROWTH-HORMONE (GH) THERAPY IN ADULTS WITH GH DEFICIENCY

Serum levels of insulin-like growth factor I (IGF-I), IGF-binding prot ein-3 (IGFBP-3), the acid-labile subunit (ALS), insulin, and IGFBP-1 w ere evaluated as indicators of body composition during GH replacement therapy in 20 GH-deficient patients (9 women and 11 men), aged 22-57 y r, with IGF-I levels below -2 SD. The mean GH dose was 0.128 +/- 0.003 IU/kg week during the first month and thereafter 0.23 +/- 0.01 IU/kg week, divided into daily doses (0.7-4.3 IU/day).Serum levels of IGF-I, ALS, and IGFBP-3 above the normal range were reached in seven, five, and three subjects, respectively, after 12 months of GH therapy. IGF-I and ALS levels, but not IGFBP-3 levels, correlated with the total dai ly GH dose (r = 0.676; P = 0.001 and r = 0.631; P = 0.003). The mean i ncrease in lean body mass (LBM) measured by dual energy x-ray absorpti ometry was 3.0 +/- 0.5 kg (P < 0.001). Pit 12 months, the LBM values w ere significantly correlated to the IGF-I levels (r = 0.718; P < 0.001 ), but not to ALS or IGFBP-3 levels. No correlation was found before t herapy, and the increase in LBM at 12 months correlated with the IGF-I increase (r = 0.514; P = 0.029) only after exclusion of two nonrespon ders. Both before and during therapy, LBM was inversely related to IGF BP-1 (r = -0.715; P < 0.004 at 12 months). None of the GK-induced prot eins could be used as indicators of body fat changes. In conclusion, b oth IGF-I and ALS can be used as indicators to avoid GH excess during replacement therapy, but only IGF-I relates to changes in LBM.