Increased serum concentration of IGFBP-4 and IGFBP-5 in healthy adults during one month's treatment with supraphysiological doses of growth hormone.
OBJECTIVE
To study the effects on insulin-like growth factor binding proteins (IGFBP)-4 and -5 after one month's treatment with supraphysiological doses of growth hormone (GH) in healthy, active young adults with a normal GH-IGF-I axis. Furthermore, the possible use of IGFBP-4 and IGFBP-5 as markers of GH doping is discussed.


METHODS
Thirty healthy, physically active volunteers (15 men and 15 women), mean age 25.9 years (range 18-35), participated in this randomized, double-blind, placebo-controlled, parallel study with three groups (n=10; 5 men and 5 women in each group). The groups comprised the following: placebo, GH 0.1IU/kg/day [0.033mg/kg/day] and GH 0.2IU/kg/day [0.067mg/kg/day].


RESULTS
Baseline levels of IGFBP-4 were higher (+20%), while IGFBP-5 levels were lower (-37%) in women than in men. IGFBP-5 levels were positively correlated to age, but no significant correlation was found for IGFBP-4. In the pooled group with active GH treatment (n=20), both IGFBP-4 and IGFBP-5 levels were increased vs. the placebo group from day 14 until end of treatment [day 28, IGFBP-4 (+40%, p<0.01) and IGFBP-5 (+61%, p <0.001)]. After inclusion of serum IGF-I as a covariate in the linear regression analysis, the associations between GH treatment and the IGFBP-4 and IGFBP-5 levels were not significant.


CONCLUSIONS
This study shows that the levels of IGFBP-4 and IGFBP-5 are affected by supraphysiological GH treatment given to young, healthy, physically active adults of both genders. The present study, including relatively few subjects, does not support that IGFBP-4 and IGFBP-5 can be used as IGF-I independent markers in a forthcoming method for detecting GH doping, although, further studies are needed to investigate the potential use of IGFBP-4 and IGFBP-5 as markers of GH doping.
Ehrnborg
Christer
C
Research Centre for Endocrinology and Metabolism (RCEM), Endocrine Division, Department of Internal Medicine, Gröna Stråket 8, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden. christer.ehrnborg@medic.gu.se
Ohlsson
Claes
C
Mohan
Subburaman
S
Bengtsson
Bengt-Ake
BA
Rosén
Thord
T
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D004300:Doping in Sports; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage*; D006801:Humans; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000097:blood*; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D012737:Sex Factors
D015415:Biomarkers; D018974:Insulin-Like Growth Factor Binding Protein 4; D018975:Insulin-Like Growth Factor Binding Protein 5; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone