Circulating IGF-I levels in monitoring and predicting efficacy during long-term GH treatment of GH-deficient adults.
OBJECTIVE
To investigate the effects of long-term GH in GH-deficient adults, as predicted by IGF-I levels.


METHODS
Patients received GH, 5 microg/kg per day for 1 Month and 10 microg/kg per day for another 12-30 Months. Changes in body composition, cardiac structure/function, serum lipids and quality of life were measured.


RESULTS
There was a significant increase in lean body mass (LBM) (2.21 kg; P<0.0001) after 6 Months, which was sustained throughout treatment. A larger increase occurred in males than females (2.97 vs 1.19 kg; P<0.0001). Total fat mass was reduced (2.56 kg; P<0.0001 (3.26 kg males, 1.63 kg females)). Responsiveness to GH varied greatly, but LBM changes correlated with IGF-I changes (P<0.004). Furthermore, thinner patients experienced greater and progressive LBM increases. There was an increase in ejection fraction (3.85+/-9.95%; P=0.0002) after 6 Months, sustained to 18 Months. These cardiac effects were equal for males and females, and did not correlate with IGF-I levels. Serum low-density lipoprotein/high-density lipoprotein ratios decreased within 6 Months, and were sustained thereafter. Quality of life improved significantly after 6 Months, an effect that was sustained/enhanced as treatment continued. No major adverse events were identified.


CONCLUSIONS
Improved body composition is both reflected by IGF-I changes and predicted inversely by baseline adiposity. Other effects of GH replacement on cardiac function, dyslipidaemia and quality of life, however, do not correlate with circulating IGF-I concentrations. Our findings validate the importance of sustained GH therapy, but caution on the interpretation of IGF-I levels in monitoring the long-term effects of GH treatment.
Ezzat
S
S
Division of Endocrinology and Metabolism, University of Toronto, Canada.
Fear
S
S
Gaillard
R-C
RC
Gayle
C
C
Marcovitz
S
S
Mattioni
T
T
Nussey
S
S
Rees
A
A
Svanberg
E
E
D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D001823:Body Composition / Q000187:drug effects*; D015992:Body Mass Index; D015519:Bone Density / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006130:Growth Disorders / Q000188:drug therapy / Q000523:psychology; D006305:Health Status Indicators; D006321:Heart / Q000187:drug effects; D020249:Hormone Replacement Therapy; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008055:Lipids / Q000097:blood; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D016896:Treatment Outcome
D015415:Biomarkers; D008055:Lipids; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I