High-affinity growth hormone (GH)-binding protein (GHBP), body fat mass, and insulin-like growth factor-binding protein-3 predict the GHBP response to GH therapy in adult GH deficiency syndrome.
The study objective was to investigate which baseline factors can accurately predict plasma high-affinity growth hormone (GH)-binding protein (GHBP) levels after GH replacement therapy in patients with GH deficiency (GHD). The study group consisted of 36 GHD patients (22 men and 14 women; mean age, 43.1 years; (range, 21 to 60) known to have adult-onset GHD for many years (range, 4 to 22). They were randomly divided into a GH-treated group (n = 19) and a placebo group (n = 17). Body composition (assessed by bioelectrical impendance analysis [BIA]), plasma GHBP (fast protein liquid chromatography [FPLC] size-exclusion gel chromatography), insulin-like growth factor-I (IGF-I), and IGF-binding protein-3 ([IGFBP-3] radioimmunoassays) were measured before and after 6 months. A stepwise multiple linear regression analysis with the plasma GHBP level after 6 months as the dependent variable was used to unravel significant explanatory (or predictor) variables. In contrast to placebo therapy, GH replacement therapy increased the mean plasma levels of IGF-I and IGFBP-3 to the normal range, whereas a small but statistically significant increase in plasma GHBP was observed. The combination of baseline plasma GHBP, body fat mass, and IGFBP-3 predicts posttreatment GHBP levels accurately (adjusted R2 = .97), indicating that baseline variables such as age, gender, fat-free mass, and IGF-I have no contribution. Furthermore, reliability analysis showed that the observed and predicted values for GHBP fit a strict parallel model. These findings indicate that the variations in body fat mass and IGFBP-3 among adult GHD subjects explain the reported variable response of GHBP to GH replacement therapy.
Roelen
C A
CA
Department of Endocrinology, University Hospital Utrecht, The Netherlands.
Koppeschaar
H P
HP
de Vries
W R
WR
Doerga
M E
ME
Snel
Y E
YE
Bol
E
E
Zelissen
P M
PM
Thijssen
J H
JH
Blankenstein
M A
MA
D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D004311:Double-Blind Method; D005260:Female; D013006:Growth Hormone / Q000009:adverse effects / Q000627:therapeutic use*; D019382:Human Growth Hormone / Q000009:adverse effects / Q000172:deficiency* / Q000627:therapeutic use*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged
D002352:Carrier Proteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein