The contribution of IGF-I to skeletal integrity in postmenopausal women.
OBJECTIVE
The pathogenic role of the decline in serum concentrations of IGF-I in postmenopausal osteoporosis is not fully elucidated. We investigated the associations among IGF-I, bone mineral density (BMD), ultrasound parameters and prevalence of vertebral fractures in postmenopausal women.


METHODS
A cross-sectional study.


METHODS
One hundred and fifty-four ambulatory postmenopausal women (61 +/- 7 years) referred for osteoporosis screening.


METHODS
IGF-I was measured by radioimmunoassay and BMD using dual-energy X-ray absorptiometry. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) at calcaneus were measured by a quantitative ultrasound system.


RESULTS
IGF-I was significantly lower in osteoporotic subjects and correlated positively with BMD, BUA and SOS. After adjusting for age, years since menopause and body mass index, IGF-I accounted for 8.5% of the variance at lumbar spine BMD, 4.6% at femoral neck and 7.1% at calcaneal BUA. BUA was associated with IGF-I independently of BMD. IGF-I was lower in women with vertebral fractures (91 +/- 39 microg/l vs. 114 +/- 44 microg/l; P = 0.003). The osteoporosis densitometric criteria (t-score < or = -2.5 SD) was the most strongly independent associated variable with prevalent vertebral fractures [odds ratio (OR): 3.3 (1.4-7.6)], followed by IGF-I levels below 75th percentile [OR: 3 (1-8.8)].


CONCLUSIONS
Our study shows that IGF-I is strongly associated with bone mineral density and reflects aspects of bone quality. The contribution of IGF-I to skeletal integrity in postmenopausal women is clinically relevant.
Muñoz-Torres
M
M
Endocrinology Division, University Hospital San Cecilio, Granada, Spain. mmt@jet.es
Mezquita-Raya
P
P
Lopez-Rodriguez
F
F
Torres-Vela
E
E
de Dios Luna
J
J
Escobar-Jimenez
F
F
D000368:Aged; D015519:Bone Density; D002111:Calcaneus / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism*; D008875:Middle Aged; D016017:Odds Ratio; D015663:Osteoporosis, Postmenopausal / Q000097:blood* / Q000000981:diagnostic imaging; D016103:Spinal Fractures / Q000097:blood / Q000000981:diagnostic imaging; D014463:Ultrasonography
D007334:Insulin-Like Growth Factor I