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Context: 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., Design, Setting, and Participants: Our cross-sectional study included 107 men diagnosed with idiopathic low bone mass, 23 of their adult sons, and 130 age-matched controls., Main Outcome Measures: 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., Conclusion: 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.

Bone health is a parameter of interest in the daily follow-up of male-to-female (M --> F) transsexual persons both before and after sex reassignment surgery (SRS) due to an intensely changing hormonal milieu. We have studied body composition, areal, geometric, and volumetric bone parameters, using DXA and peripheral quantitative computed tomography at different sites in 50 M --> F transsexual persons, at least 3 yr after the start of the hormonal treatment and 1 yr after SRS. In this cross-sectional study, hormone levels and markers of bone metabolism were assessed using immunoassays. Prevalence of low bone mass as defined by a Z-score < or = -2.0 according to DXA criteria was 26% at lumbar spine and 2% at the total hip. We found no major differences in hormonal parameters between participants with a Z-score < or = or > -2.0. Markers of bone turnover were comparable between subjects with or without low bone mass, indicating a stable bone turnover at the time of investigation. No significant differences in bone size or density were observed between patients on transdermal vs. oral estrogens. Low bone mass is not uncommon in M --> F transsexual persons. Smaller bone size, and a strikingly lower muscle mass compared with men appear to underlie these findings.

Context: Bone mass is under strong genetic control, with heritability estimates greater than 50% and is likely determined by complex interactions between genetic and environmental factors., Objective: The objective of the study was to localize genes contributing to bone mineral density (BMD) variation., Design: An autosomal genome-wide scan for BMD at the lumbar spine and femoral neck was conducted with variance components linkage methods., Participants: A total of 103 pedigrees (Network in Europe on Male Osteoporosis Family Study) ascertained through a male relative with low (Z-score < or = -2) BMD values at either lumbar spine or femoral neck., Main Outcome Measures: Nonparametric multipoint logarithm of the odds ratio scores for lumbar spine and femoral neck BMD values adjusted for age, gender, and body mass index., Results: We identified a total of eight chromosomal regions with logarithm of the odds ratio score of 1.5 or greater (P < or = 5 x 10(-3)): on 1q42-43, 11q12-13, 12q23-24, 17q21-23, 21q22, and 22q11 for lumbar spine and on 5q31-33 and 13q12-14 for femoral neck BMD., Conclusions: Four of our detected quantitative trait loci (QTL) reached the genome-wide criteria for significant (17q,21-23, P < or = 2 x 10(-5)) or suggestive (11q12-13, 22q11, and 13q12-14, P < or = 7 x 10(-4)) linkage. Apart from 22q11, which is a novel QTL, all other loci provide consistent replication for previously reported QTLs for BMD and other bone-related traits. Finally, several of our specific-linkage areas encompass prominent candidate genes: type 1 collagen (COL1A1) and the sclerosteosis/van Buchem disease (SOST) genes on 17q21-23; the low-density lipoprotein receptor-related protein 5 (LRP5) gene on 11q12-13; and the rank ligand gene on 13q12-14. Further analysis of these positive regions by fine linkage disequilibrium mapping is thus warranted.

Summary: Although trans women before the start of hormonal therapy have a less bone and muscle mass compared with control men, their bone mass and geometry are preserved during the first 2 years of hormonal therapy, despite of substantial muscle loss, illustrating the major role of estrogen in the male skeleton. Purpose: The aim of this study is to examine the evolution of areal and volumetric bone density, geometry, and turnover in trans women undergoing sex steroid changes, during the first 2 years of hormonal therapy. Methods: In a prospective observational study, we examined 49 trans women (male-to-female) before and after 1 and 2 years of cross-sex hormonal therapy (CSH) in comparison with 49 age-matched control men measuring grip strength (hand dynamometer), areal bone mineral density (aBMD), and total body fat and lean mass using dual X-ray absorptiometry (DXA), bone geometry and volumetric bone mineral density, regional fat, and muscle area at the forearm and calf using peripheral quantitative computed tomography. Standardized treatment regimens were used with oral estradiol valerate, 4 mg daily (or transdermal 17-β estradiol 100 μg/24 h for patients >45 years old), both combined with oral cyproterone acetate 50 mg daily. Results: Prior to CSH, trans women had lower aBMD at all measured sites (all p < 0.001), smaller cortical bone size (all p < 0.05), and lower muscle mass and strength and lean body mass (all p < 0.05) compared with control men. During CSH, muscle mass and strength decreased and all measures of fat mass increased (all p < 0.001). The aBMD increased at the femoral neck, radius, lumbar spine, and total body; cortical and trabecular bone remained stable and bone turnover markers decreased (all p < 0.05). Conclusions: Although trans women, before CSH, have a lower aBMD and cortical bone size compared with control men, their skeletal status is well preserved during CSH treatment, despite of substantial muscle loss. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Cross-sex hormonal therapy and sex reassignment surgery (including gonadectomy) in transsexual persons has an impact on body composition and bone mass and size. However, it is not clear whether baseline differences in bone and body composition between transsexual persons and controls before cross-sex hormonal therapy play a role. Design: A cross-sectional study with 25 male-to-female transsexual persons (transsexual women) before cross-gender sex steroid exposure (median age 30years) in comparison with 25 age-matched control men and a male reference population of 941 men. Main outcome measures: Areal and volumetric bone parameters using respectively dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), body composition (DXA), grip strength (hand dynamometer), Baecke physical activity questionnaire, serum testosterone and 25-OH vitamin D. Results: Transsexual women before cross-sex hormonal therapy presented with less muscle mass (p ≤0.001) and strength (p ≤0.05) and a higher prevalence of osteoporosis (16%) with a lower aBMD at the hip, femoral neck, total body (all p <0.001) and lumbar spine (p =0.064) compared with control men. A thinner radial cortex (p ≤0.01) and lower cortical area at the radius and tibia (both p <0.05) was found in transsexual women vs. control men. Serum testosterone was comparable in all 3 groups, but 25-OH vitamin D was lower in transsexual women (p ≤0.001). Conclusions: Transsexual women before the start of hormonal therapy appear to have lower muscle mass and strength and lower bone mass compared with control men. These baseline differences in bone mass might be related to a less active lifestyle. [Copyright &y& Elsevier]