title: Age-related changes in cortical bone content of insulin-like growth factor binding protein (IGFBP)-3, IGFBP-5, osteoprotegerin, and calcium in postmenopausal osteoporosis: a cross-sectional study.
abstract: Serum GH and IGF-I levels decline with increasing age, whereas osteoprotegerin (OPG) increases. IGFs as well as OPG are present in bone matrix and mediate the effects of many upstream hormones (e.g. estrogen). To evaluate whether changes in these proteins may to some extent explain the decrease in bone mass in postmenopausal or senile osteoporosis, we measured bone contents of IGF-I, IGF-II, IGF binding protein (IGFBP)-3, IGFBP-5, and OPG in combined extracts obtained after EDTA and guanidine hydrochloride extraction in 60 postmenopausal women aged 47-74 (mean, 63) yr with a previous distal forearm fracture and a hip or spine Z-score less than 0. We found age-related increases in IGFBP-3 (r = 0.35; P < 0.01), IGFBP-5 (r = 0.59; P < 0.001), and OPG (r = 0.36; P < 0.01) in cortical bone, significantly inversely correlated with femoral neck and lumbar spine BMD. A correlation between age and OPG was also detected in trabecular bone (r = 0.27; P < 0.05). A pronounced age-related decrease in cortical calcium contents (r = -0.60; P < 0.001), positively correlated with femoral neck and lumbar spine BMD, was also found. No age-related changes were detected for IGF-I or IGF-II. The present study demonstrates age-related changes in cortical bone contents of IGFBPs, calcium, and OPG, possibly related to the pathophysiology of postmenopausal osteoporosis. As for OPG, our findings probably represent compensatory responses to increased osteoclastic resorption.
authors.affiliation: Department of Endocrinology, and Research Institute for Internal Medicine National, University Hospital, N-0027 Oslo, Norway. thor.ueland@klinmed.uio.no
authors.forename: Thor
authors.initials: T
authors.lastname: Ueland
authors.forename: Kim
authors.initials: K
authors.lastname: Brixen
authors.forename: Lis
authors.initials: L
authors.lastname: Mosekilde
authors.forename: Leif
authors.initials: L
authors.lastname: Mosekilde
authors.forename: Allan
authors.initials: A
authors.lastname: Flyvbjerg
authors.forename: Jens
authors.initials: J
authors.lastname: Bollerslev
mesh_terms: D000367:Age Factors; D000368:Aged; D015519:Bone Density; D001842:Bone and Bones / Q000737:chemistry*; D002118:Calcium / Q000032:analysis*; D003430:Cross-Sectional Studies; D005260:Female; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000032:analysis*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000378:metabolism*; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis*; D018124:Receptors, Tumor Necrosis Factor
chemical_list: D006023:Glycoproteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D018975:Insulin-Like Growth Factor Binding Protein 5; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D002118:Calcium