Bioactive insulin-like growth factor (IGF) I and IGF-binding protein-1 in anorexia nervosa.
BACKGROUND
Regulation of IGF-I activity appears crucial in anorexia nervosa (AN) during adaptation to chronic starvation as well as during the regenerative processes on nutritional restoration.


OBJECTIVE
The objective of this study was to examine the relationship between IGF-I bioactivity and IGF-binding capacity as expressed as formation of the binary complex of IGF-binding protein-1 (IGFBP-1) and IGF-I in patients with AN at different stages and with different subtypes of the disease.


METHODS
This was a longitudinal study.


METHODS
The study took place at a clinical research center at a university hospital.


METHODS
We studied a total of 45 women with AN and 24 age-comparable healthy controls.


METHODS
IGF-I bioactivity was determined using an IGF-I receptor activation assay, and IGF-I/IGFBP-1 complex formation was determined by an assay that allows direct determination of the binary complex.


RESULTS
IGF-I bioactivity was significantly decreased in serum from patients with AN. We found significant correlations between total, ultrafiltered free, and bioactive IGF-I. Despite increased IGFBP-1 concentrations, levels of IGF-I/IGFBP-1 binary complex were not significantly increased in AN. Oral contraceptives were associated with increased levels of IGF-I, IGFBP-1, and binary complex formation. Ghrelin levels were only significantly raised in those patients who had lost more than 5% of the body weight during the last 4 wk, whereas ghrelin levels in weight-stable as well as in weight-gaining patients did not significantly differ from the controls.


CONCLUSIONS
Total IGF-I level is a suitable marker of IGF-I bioactivity in emaciated patients with AN irrespective of the clinical subtype and acute nutritional state.
Støving
René Klinkby
RK
Department of Endocrinology, Odense University Hospital, Odense, Denmark. rene.k.stoving@dadlnet.dk
Chen
Jian-Wen
JW
Glintborg
Dorte
D
Brixen
Kim
K
Flyvbjerg
Allan
A
Hørder
Kirsten
K
Frystyk
Jan
J
D015502:Absorptiometry, Photon; D052242:Adiponectin / Q000378:metabolism; D000328:Adult; D000856:Anorexia Nervosa / Q000178:diet therapy / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism*; D001835:Body Weight / Q000502:physiology; D002460:Cell Line; D004435:Eating / Q000502:physiology; D005260:Female; D054439:Ghrelin; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D008137:Longitudinal Studies; D036361:Peptide Hormones / Q000378:metabolism; D014162:Transfection
C499918:ADIPOQ protein, human; D052242:Adiponectin; D015415:Biomarkers; D054439:Ghrelin; C032231:IGFBP1 protein, human; D018970:Insulin-Like Growth Factor Binding Protein 1; D036361:Peptide Hormones; D007334:Insulin-Like Growth Factor I