Anthropometric and skeletal phenotype in men with idiopathic osteoporosis and their sons is consistent with deficient estrogen action during maturation.
BACKGROUND
Pathophysiology of deficient bone mass acquisition in male idiopathic osteoporosis (IO) remains poorly understood.


OBJECTIVE
Our objective was to investigate volumetric and geometric parameters of the appendicular skeleton, biochemical markers, and anthropometrics in men with IO.


METHODS
Our cross-sectional study included 107 men diagnosed with idiopathic low bone mass, 23 of their adult sons, and 130 age-matched controls.


METHODS
Body composition and areal bone parameters (dual-energy x-ray absorptiometry) and volumetric and geometric parameters of radius and tibia (peripheral quantitative computed tomography) were assessed. Serum levels of testosterone, estradiol (E(2)), and SHBG, and bone turnover markers were measured using immunoassays. Free hormone fractions were calculated.


RESULTS
Men with idiopathic low bone mass had lower weight (-9.6%), truncal height (-3.3%), and upper/lower body segment ratio (-2.7%; all P < 0.001) and presented at the radius and tibia lower trabecular (-19.0 and -23.6%, respectively; both P < 0.001) and cortical volumetric bone mineral density (vBMD) (-2.4 and -1.7%; both P < 0.001) and smaller cortical areas (-9.7 and -13.6%; both P < 0.001) and thicknesses (-13.5 and -14.5%, both P < 0.001) due to larger endosteal circumferences (+11.8 and +7.4%, both P < 0.001) than controls. Furthermore, (free) E(2) was lower and SHBG higher (both P < 0.01). Their sons had lower trabecular vBMD (-10.3%, P = 0.036) and a thinner cortex (-8.3%, P = 0.024) at the radius.


CONCLUSIONS
Bone mass deficits in men with idiopathic low bone mass involve trabecular and cortical bone, resulting from lower vBMD and smaller cortical bone cross-sectional areas and thicknesses. A similar bone phenotype is present in at least part of their sons. The lower E(2), together with characteristics as lower upper/lower body segment ratio, larger endosteal circumferences and lower vBMD, may indicate an estrogen-related factor in the pathogenesis of male IO.
Lapauw
Bruno
B
Department of Endocrinology and Unit for Osteoporosis and Metabolic Bone Diseases, Ghent University Hospital, B-9000 Ghent, Belgium. Bruno.Lapauw@ugent.be
Taes
Youri
Y
Goemaere
Stefan
S
Toye
Kaatje
K
Zmierczak
Hans-Georg
HG
Kaufman
Jean-Marc
JM
D000328:Adult; D000375:Aging / Q000502:physiology*; D000886:Anthropometry / Q000379:methods*; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D001842:Bone and Bones / Q000378:metabolism; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000172:deficiency*; D005269:Femur / Q000033:anatomy & histology; D007839:Functional Laterality; D006801:Humans; D007006:Hypogonadism / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000235:genetics* / Q000503:physiopathology*; D011884:Radius / Q000033:anatomy & histology; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013131:Spine / Q000033:anatomy & histology; D013739:Testosterone / Q000097:blood; D013977:Tibia / Q000033:anatomy & histology
D004967:Estrogens; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol