Association between serum insulin-like growth factor-I levels and thyroid disorders in a population-based study.
OBJECTIVE
There is current debate on whether serum IGF-I levels are associated with thyroid disorders. The aims of the present study were: 1) to investigate possible associations between serum IGF-I levels and thyroid disorders and 2) to analyze the role of serum IGF binding protein (IGFBP)-3 and TSH levels for these associations.


METHODS
This was a cross-sectional Study of Health in Pomerania.


METHODS
The study was conducted in the general population of northeast Germany.


METHODS
The study population comprised 3662 subjects (1746 women) without history of thyroid disorders.


METHODS
No interventions have been performed.


METHODS
Goiter and thyroid nodules were determined by ultrasound. Serum TSH levels less than 0.25 mIU/liter were considered decreased.


RESULTS
Adjusted for major confounders and risk factors for thyroid disorders, subjects with serum IGF-I levels above the upper tertile had higher odds for goiter relative to subjects with serum IGF-I levels below the lower tertile [odds ratio (OR) 1.67; 95% confidence interval (CI) 1.24-2.26 in women; OR 2.04; 95% CI 1.55-2.68 in men]. A similar association was present for thyroid nodules in men (OR 1.64; 95% CI 1.17-2.32) and for decreased serum TSH levels in women (OR 1.65; 95% CI 1.00-2.69). Serum IGFBP-3 levels were not associated with thyroid disorders and did not represent effect modifiers for the association between serum IGF-I levels and the endpoints.


CONCLUSIONS
We conclude that high serum IGF-I levels are associated with goiter. Whereas high serum IGF-I levels are also related to thyroid nodules in men, they are related to decreased serum TSH levels in women. Serum IGFBP-3 and TSH levels did not modulate these associations.
Institute of Community Medicine, University of Greifswald, D-17487 Greifswald, Germany. voelzke@uni-greifswald.de
Henry
H
Völzke
Nele
N
Friedrich
Sabine
S
Schipf
Robin
R
Haring
Jan
J
Lüdemann
Matthias
M
Nauck
Marcus
M
Dörr
Georg
G
Brabant
Henri
H
Wallaschofski
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany / Q000453:epidemiology; D006042:Goiter / Q000097:blood* / Q000453:epidemiology*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D017678:Sex Distribution; D016606:Thyroid Nodule / Q000097:blood* / Q000453:epidemiology*; D013972:Thyrotropin / Q000097:blood
C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D013972:Thyrotropin