Bi-allelic Loss-of-Function Mutations in the NPR-C Receptor Result in Enhanced Growth and Connective Tissue Abnormalities.

The natriuretic peptide signaling pathway has been implicated in many cellular processes, including endochondral ossification and bone growth. More precisely, different mutations in the NPR-B receptor and the CNP ligand have been identified in individuals with either short or tall stature. In this study we show that the NPR-C receptor (encoded by NPR3) is also important for the regulation of linear bone growth. We report four individuals, originating from three different families, with a phenotype characterized by tall stature, long digits, and extra epiphyses in the hands and feet. In addition, aortic dilatation was observed in two of these families. In each affected individual, we identified a bi-allelic loss-of-function mutation in NPR3. The missense mutations (c.442T>C [p.Ser148Pro] and c.1088A>T [p.Asp363Val]) resulted in intracellular retention of the NPR-C receptor and absent localization on the plasma membrane, whereas the nonsense mutation (c.1524delC [p.Tyr508∗]) resulted in nonsense-mediated mRNA decay. Biochemical analysis of plasma from two affected and unrelated individuals revealed a reduced NTproNP/NP ratio for all ligands and also high cGMP levels. These data strongly suggest a reduced clearance of natriuretic peptides by the defective NPR-C receptor and consequently increased activity of the NPR-A/B receptors. In conclusion, this study demonstrates that loss-of-function mutations in NPR3 result in increased NPR-A/B signaling activity and cause a phenotype marked by enhanced bone growth and cardiovascular abnormalities.

The effects of age and obesity on postprandial dynamics of serum testosterone levels in men.

OBJECTIVE: Guidelines recommend using fasting samples to evaluate testosterone (T) levels in men, as free and total T levels decrease postprandially. However, it is not clear whether these dynamics are affected by age or obesity. This could be relevant given the obesity epidemic, ageing population and the barrier for screening which fasting could impose. DESIGN/PARTICIPANTS: A total of 43 men underwent a solid mixed meal tolerance test. Serum samples were taken fasting, and at 30, 60 and 120 minutes postprandially. A commercial immunoassay was used to determine sex hormone-binding globulin (SHBG) levels, liquid chromatography coupled to tandem mass spectroscopy for total T concentrations and free T levels were calculated. RESULTS: Postprandially, both total and free T were lower at all-time points compared with fasting (all, P < .005). At 60 minutes, maximum mean decreases of 15 ± 15% and 17 ± 16% were seen for total and free T levels, respectively. Younger men had greater decreases in both total and free T levels compared with men older than 40 years (all, P < .05). A greater decrease at 30 and 60 minutes postprandially was observed for both total and free T levels in nonobese vs obese men (all, P < .05). CONCLUSIONS: After a mixed meal, total and free T serum levels decreased whereas SHBG levels did not change. Interestingly, postprandial decreases were less pronounced in men older than 40 years and/or with obesity. Although this study indicates less pronounced decreases in certain men, fasting samples remain a prerequisite for establishing correct diagnosis of male hypogonadism.

Validation of the FNIH sarcopenia criteria and SOF frailty index as predictors of long-term mortality in ambulatory older men.

OBJECTIVE: we aimed to evaluate the Foundation for the National Institutes of Health (FNIH) criteria for weakness and low muscle mass and the Study of Osteoporotic Fractures (SOF) frailty index for prediction of long-term, all-cause mortality. DESIGN: community-based cohort study. SETTING: semi-rural community of Merelbeke (Belgium). SUBJECTS: ambulatory men aged 74 and more (n = 191). METHODS: weakness was defined on previously established criteria as low grip strength (<26 kg) or low grip strength-to-body mass index (BMI) ratio (<1.00). Low muscle mass (dual-energy x-ray absorptiometry) was categorised as low appendicular lean mass (ALM; predefined <19.75 kg) or low ALM-to-BMI ratio (predefined <0.789). Frailty status was assessed using the components of weight loss, inability to rise from a chair and poor energy (SOF index). Survival time was calculated as the number of months from assessment in 2000 until death or up to 15 years of follow-up. RESULTS: mean age of the participants was 78.4 ± 3.5 years. Combined weakness and low muscle mass was present in 3-8% of men, depending on the criteria applied. Pre-frailty and frailty were present in 30 and 7% of men, respectively. After 15 years of follow-up, 165 men (86%) died. Both the presence of combined weakness and low ALM-to-BMI ratio (age-adjusted HR = 2.50, 95% CI = 1.30-4.79) and the presence of SOF frailty (age-adjusted HR = 2.64, 95% CI = 1.44-4.86) were associated with mortality. CONCLUSIONS: our findings confirm the predictive value for mortality of the non-distribution-based FNIH criteria and SOF index in older community-dwelling Belgian men.

Cross-sex hormone therapy in trans persons is safe and effective at short-time follow-up: results from the European network for the investigation of gender incongruence.

INTRODUCTION: Data on the effects of cross-sex hormone therapy (CHT) are limited due to the low prevalence of gender dysphoria, small number of subjects treated at each center, lack of prospective studies, and wide variations in treatment modalities. AIM: The aim of this study is to report the short-term effects of CHT on hormonal and clinical changes, side effects, and adverse events in trans men (female-to-male gender dysphoric persons) and trans women (male-to-female gender dysphoric persons). METHODS: This was a multicenter 1-year prospective study in 53 trans men and 53 trans women. Trans men received injections of testosterone undecanoate every 3 months. Trans women younger than 45 years received 50 mg cyproterone acetate (CA) and 4 mg estradiol valerate daily, whereas those older than 45 years received 50 mg CA daily together with 100 µg/24 hours transdermal 17-ß estradiol. MAIN OUTCOME MEASURES: Sex steroids, prolactin, liver enzymes, lipids, hematocrit, blood pressure, anthropometrics, Ferriman and Gallwey score, and global acne grading scale were measured. Side effects, adverse events, and desired clinical changes were examined. RESULTS: No deaths or severe adverse events were observed. Two trans men developed erythrocytosis, and two had transient elevation of the liver enzymes. Trans men reported an increase in sexual desire, voice instability, and clitoral pain (all P ≤ 0.01). Testosterone therapy increased acne scores, facial and body hair, and prevalence of androgenetic alopecia. Waist-hip ratio, muscle mass, triglycerides, total cholesterol (C), and LDL-C increased, whereas total body fat mass and HDL-C decreased. Three trans women experienced transient elevation of liver enzymes. A significant increase in breast tenderness, hot flashes, emotionality, and low sex drive was observed (all P ≤ 0.02). Fasting insulin, total body fat mass, and prolactin levels increased, and waist-hip ratio, lean mass, total C, and LDL-C decreased. CONCLUSIONS: Current treatment modalities were effective and carried a low risk for side effects and adverse events at short-time follow-up.

Short- and long-term clinical skin effects of testosterone treatment in trans men.

INTRODUCTION: Our knowledge concerning the effects of testosterone (T) therapy on the skin of trans men (female-to-male transsexuals) is scarce. AIM: The aim of this study was to evaluate the short- and long-term clinical effects of T treatment on the skin of trans men. METHODS: We conducted a prospective intervention study in 20 hormone naive trans men and a cross-sectional study in 50 trans men with an average of 10 years on T therapy. MAIN OUTCOME MEASURES: Acne lesions were assessed using the Gradual Acne Grading Scale, hair patterns using the Ferriman and Gallwey classification (F&G), and androgenetic alopecia using the Norwood Hamilton Scale. RESULTS: T treatment increased facial and body hair growth. The F&G score increased progressively from a median value of 0.5 at baseline to a value of 12 after 12 months of T administration. After long-term T treatment, all but one trans man achieved an F&G score indicative of hirsutism in women, with a median value of 24. Only one trans man acquired mild frontotemporal hair loss during the first year of T treatment, whereas 32.7% of trans men had mild frontotemporal hair loss and 31% had moderate to severe androgenetic alopecia after long-term T therapy. The presence and severity of acne increased during the first year of T therapy, and peaked at 6 months. After long-term T treatment, most participants had no or mild acne lesions (93.9%). Dermatological outcome was not demonstrably related to individual serum T or dihydrotestosterone levels. CONCLUSIONS: T treatment increased facial and body hair in a time-dependent manner. The prevalence and severity of acne in the majority of trans men peaked 6 months after beginning T therapy. Severe skin problems were absent after short- and long-term T treatment.

Physical function measurements predict mortality in ambulatory older men.

BACKGROUND: To assess and compare the predictive value of physical function measurements (PFMs) for all-cause mortality in older men and to evaluate the Timed Up and Go test (TUG) as a predictor in subjects with underlying comorbidity. DESIGN: Observational study of a population-based sample of 352 ambulatory older men aged 71-86 at study baseline. The Rapid disability rating scale-2, 36-Item short form health survey, Grip strength, Five times sit-to-stand test, Standing balance, and TUG were determined at baseline. Associations with all-cause mortality were assessed using Cox proportional hazard analyses. Age, Body mass index (BMI), smoking status, education, physical activity and cognitive status were included as confounders. Follow-up exceeded 15 years. Comorbidity status was categorized into cardiovascular disease, chronic obstructive pulmonary disease (COPD) and diabetes mellitus. RESULTS: All examined PFMs were associated with all-cause mortality. TUG was the best predictor (adjusted HR per SD increase = 1·58, 95% CI = 1·40-1·79, P < 0·001) for global mortality and continued to be predictive in subjects with cardiovascular disease (adjusted HR per SD increase = 1·80, 95% CI = 1·40-2·33, P < 0·001). CONCLUSIONS: The assessment of physical functioning is important in the evaluation of older persons. We encourage the use of the TUG as a reliable, quick and feasible screening tool in clinical settings.

Long-term evaluation of donor-site morbidity after radial forearm flap phalloplasty for transsexual men.

INTRODUCTION: Phalloplasty using the radial forearm flap is currently the most frequently used technique to create the neophallus in transsexual men (formerly described as female-to-male transsexual persons). Although it is considered the gold standard, its main disadvantage is the eventual donor-site morbidity in a young, healthy patient population. AIM: The study aims to examine the long-term effects of radial forearm flap phalloplasty in transsexual men and to evaluate aesthetic outcome, scar acceptance, bone health, and daily functioning. MAIN OUTCOME MEASURES: Scars were evaluated with the patient and observer scar assessment scale, the Vancouver Scar Scale, and self-reported satisfaction. Bone health was assessed using dual X-ray absorptiometry and peripheral quantitative computed tomography, and daily functioning using a physical activity questionnaire (Baecke). These measurements were compared with 44 age-matched control women. METHODS: This is a cross-sectional study of 44 transsexual, a median of 7 years after radial forearm flap phalloplasty, recruited from the Center for Sexology and Gender Problems at the Ghent University Hospital, Belgium. RESULTS: We observed no functional limitations on daily life activities, a pain-free and rather aesthetic scar, and unaffected bone health a median of 7 years after radial foreram flap phalloplasty. Over 75% of transsexual men were either satisfied or neutral with the appearance of the scar. CONCLUSIONS: Transsexual men, despite scarring the forearm, consider the radial forearm flap phalloplasty as worthwhile.

Quality of life and sexual health after sex reassignment surgery in transsexual men.

INTRODUCTION: Although sexual health after genital surgery is an important outcome factor for many transsexual persons, little attention has been attributed to this subject. AIMS: To provide data on quality of life and sexual health after sex reassignment surgery (SRS) in transsexual men. METHODS: A single-center, cross-sectional study in 49 transsexual men (mean age 37 years) after long-term testosterone therapy and on average 8 years after SRS. Ninety-four percent of the participants had phalloplasty. MAIN OUTCOME MEASURES: Self-reported physical and mental health using the Dutch version of the Short Form-36 Health Survey; sexual functioning before and after SRS using a newly constructed specific questionnaire. RESULTS: Compared with a Dutch reference population of community-dwelling men, transsexual men scored well on self-perceived physical and mental health. The majority reported having been sexually active before hormone treatment, with more than a quarter having been vaginally penetrated frequently before starting hormone therapy. There was a tendency toward less vaginal involvement during hormone therapy and before SRS. Most participants reported an increase in frequency of masturbation, sexual arousal, and ability to achieve orgasm after testosterone treatment and SRS. Almost all participants were able to achieve orgasm during masturbation and sexual intercourse, and the majority reported a change in orgasmic feelings toward a more powerful and shorter orgasm. Surgical satisfaction was high, despite a relatively high complication rate. CONCLUSION: Results of the current study indicate transsexual men generally have a good quality of life and experience satisfactory sexual function after SRS.

Polymorphisms of the SHBG gene contribute to the interindividual variation of sex steroid hormone blood levels in young, middle-aged and elderly men.

OBJECTIVE: In men there is a large interindividual variation of SHBG levels and consequently of testosterone (T) and E(2) levels. Family and twin studies suggested a strong genetic contribution, besides metabolic and hormonal influences. The aim of this study was to examine the influence of a missense mutation in exon 8 (Asp327Asn) and a (TAAAA)(n)-repeat in the promoter region of the SHBG gene, on SHBG and sex steroid serum concentrations in a population of healthy men. DESIGN: SHBG and hormone levels were measured in 1485 men, contributed by three independent cohort studies and representing three different age groups (young, middle-aged and elderly men). The number of TAAAA-repeats was determined by fragment-analysis; carriers of the Asn(327)-allele were identified using restriction fragment length polymorphism analysis. RESULTS: In the different age groups, carriers of six TAAAA-repeats presented with higher SHBG (young 19%, middle-aged 20% and elderly 26%; P < 0.001) and T (young 9%, middle-aged 22% and elderly 21%; P < 0.05) levels compared to non-carriers. For free T, a modest increase was found for carriers in the middle-aged group, but not for the young and elderly group. E(2) and free E(2) did not differ between carriers and non-carriers in the different age-groups. The Asn(327)-allele was associated with higher mean SHBG (14.20%, P < 0.001) and T levels (7.33%; P = 0.01) in the middle-aged group only. CONCLUSIONS: Our findings show that and the (TAAAA)(n)-repeat and the Asp327Asn polymorphism contribute to the genetically determined interindividual variation in total serum T levels in healthy men through variation in SHBG concentrations.

Prevalence of low bone mass in relation to estrogen treatment and body composition in male-to-female transsexual persons.

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.

Genome-wide linkage screen of bone mineral density (BMD) in European pedigrees ascertained through a male relative with low BMD values: evidence for quantitative trait loci on 17q21-23, 11q12-13, 13q12-14, and 22q11.

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.

Proandrogenic and Antiandrogenic Progestins in Transgender Youth: Differential Effects on Body Composition and Bone Metabolism.

Context: Progestins can be used to attenuate endogenous hormonal effects in late-pubertal transgender (trans) adolescents (Tanner stage B4/5 and G4/5). Currently, no data are available on the effects of progestins on the development of bone mass or body composition in trans youth. Objective: To study prospectively the evolution of body composition and bone mass in late-pubertal trans adolescents using the proandrogenic or antiandrogenic progestins lynestrenol (L) and cyproterone acetate (CA), respectively. Design and Outcome Measurements: Forty-four trans boys (Tanner B4/5) and 21 trans girls (Tanner G4/5) were treated with L or CA for 11.6 (4 to 40) and 10.6 (5 to 31) months, respectively. Anthropometry, grip strength, body composition, and bone mass, size, and density were determined by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography before the start of progestin and before addition of cross-sex hormones. Results: Using L, lean mass [+3.2 kg (8.6%)] and grip strength [+3 kg (10.6%)] significantly increased, which coincided with a more masculine body shape in trans boys. Trans girls showed loss of lean mass [-2.2 kg (4.7%)], gain of fat mass [+1.5 kg (9.4%)], and decreased grip strength Z scores. CA limited normal bone expansion and impeded pubertal bone mass accrual, mostly at the lumbar spine [Z score: -0.765 to -1.145 (P = 0.002)]. L did not affect physiological bone development. Conclusion: Proandrogenic and antiandrogenic progestins induce body composition changes in line with the desired appearance within 1 year of treatment. Bone health, especially at the lumbar spine, is of concern in trans girls, as bone mass accrual is severely affected by androgen suppressive therapy.

Three year functional changes and long-term mortality hazard in community-dwelling older men.

BACKGROUND: Low levels of physical function have been associated with higher mortality hazard in older persons. However, few studies have investigated the association between functional changes and subsequent mortality. This study aimed to examine whether 3-year functional changes independently predict subsequent all-cause mortality. METHODS: This population-based cohort study included 171 community-dwelling men aged ≥71years at wave 2 (baseline of the present analysis), living in the semi-rural community of Merelbeke (Belgium). Physical function assessments included the Short Form-36 (SF-36) Physical Function Index, Grip strength, Chair rising, and Timed Up and Go. Changes over a 3-year time were calculated using data obtained at four annual visits. RESULTS: After a 15-year follow-up, 149 men (87%) died. Median survival time was 8.2 (4.2-12.4) years. Physical function assessed at a single time point (at wave 2 or wave 5) was significantly associated with subsequent mortality hazard, independently from future or preceding 3-year changes. Greater functional declines during the 3-year follow-up were associated with higher mortality hazards. These associations were 1) more pronounced within the first seven years, 2) independent from baseline age, polypharmacy, depression, disability, and physical function, and 3) no longer significant when closure physical function was taken into account. CONCLUSION: Physical function assessed at a single time point is a robust predictor of all-cause long-term mortality in community-dwelling older men. Yet, repeated assessments of physical function can provide prognostic information beyond that available from single initial assessment. However, with repeated assessments, most prognostic information can be found in the final assessment of physical function.

Heredity and lifestyle in the determination of between-subject variation in thyroid hormone levels in euthyroid men.

OBJECTIVE: Variation in thyroid hormone (TH) concentrations between subjects is greater than in a single subject over a prolonged period of time, suggesting an individual set point for thyroid function. We have previously shown that TH levels within normal range are associated with clinical indices such as bone mass, BMI, and heart rate. The aim of this study on young men was therefore to gain insight into the determinants of variation in TH levels among healthy subjects. METHODS: Healthy male siblings (n=941, 25-45 years) were recruited in a cross-sectional, population-based study; a history or treatment of thyroid disease and thyroid auto-immunity were exclusion criteria. A complete assessment of TH status was performed (TSH, free thyroxine (FT4), free triiodothyronine (FT3), thyroperoxidase, and thyroglobulin antibodies, reverse T3 (rT3), thyroid-binding globulin (TBG), and urinary iodine levels). Genotyping was performed by TaqMan and KASP (KBiosciences) genotyping assays. RESULTS: (F)T4, rT3, and TBG had heritability estimates between 80 and 90%. Estimates were lower for (F)T3 (60%) and lowest for TSH (49%). Significant associations were observed between different single-nucleotide polymorphisms (SNPs) in the thyroid pathway and TSH, FT4, ratio FT3:FT4, and rT3. Nevertheless, these SNPs only explain a limited part of the heredity. As to age and lifestyle-related factors, (F)T3 was negatively related to age and education level, positively to smoking and BMI (all P<0.0001) but not substantially to urinary iodine concentrations. Smoking was also negatively related to TSH and positively to FT4. CONCLUSION: Both genetic and lifestyle-related factors play a role in determining between-subject variation in TH levels in euthyroid young men, although genetic factors seem most important.

Associations between single nucleotide polymorphisms in thyroid hormone transporter genes (MCT8, MCT10 and OATP1C1) and circulating thyroid hormones.

BACKGROUND: Thyroid hormone (TH) action takes place intracellularly; therefore, transport across the plasma membrane by specific TH transporters, such as MCT8, MCT10 and OATP1C1, is necessary. Several single nucleotide polymorphisms (SNPs) in these genes were reported to be associated with TH concentrations; however, results have been inconsistent. METHODS: Six SNPs in TH transporter genes (rs5937843-G/T and rs6647476-T/C in MCT8, rs14399-C/A in MCT10, rs10444412-C/T, rs10770704-C/T and rs36010656-C/A in OATP1C1) were genotyped in 2 cohorts; one consisting of 2416 men and women aged 35-55 yrs (Asklepios), and the other of 941 men aged 25-45 yrs (Siblos), using KASPar technology. TSH, FT3, FT4 and total T3 were determined by immuno-electrochemiluminescence in both cohorts; in the second cohort additional determination of total T4 by electrochemiluminescence and of reverse T3 (rT3) and thyroid binding globulin (TBG) by radioimmunoassays was performed. RESULTS: The first SNP in MCT8 (rs5937843-G/T) was inversely associated with FT4 concentrations in men but not in women. In Siblos, this SNP showed also negative associations with TT4 and rT3; in men from Asklepios a trend for positive association with TSH was observed. The second SNP in MCT8 (rs6647476-T/C) was negatively associated with FT3 levels in men from the Siblos and the Asklepios cohort. In addition, an inverse association with TT3 levels in men from the Siblos was observed. Rs36010656 (C/A) in OATP1C1 was not in Hardy-Weinberg equilibrium and therefore excluded from further analyses. The other 2 SNPs in OATP1C1 (rs10444412-C/T and rs10770704-C/T) and the SNP in MCT10 (rs14399-C/A) were not related to TH levels in either cohort. CONCLUSION: Two SNPs in MCT8 were related to circulating thyroid hormone levels in men but not in women: the rs5937843 polymorphism (G/T) was inversely associated with FT4 levels and the rs6647476 (T/C) polymorphism related negatively to circulating FT3.

Body composition and metabolic parameters are associated with variation in thyroid hormone levels among euthyroid young men.

OBJECTIVE: Thyroid disorders affect metabolism and body composition. Existing literature has been conflicting on whether this is also the case for thyroid hormone levels within the euthyroid range. Therefore, we have investigated the relationship between thyroid hormone concentrations and body composition together with metabolic parameters in a population of healthy euthyroid men. METHODS: Healthy male siblings (n=941, 25-45 years, median BMI 24.6) were recruited in a cross-sectional, population-based study; a history or treatment of thyroid disease and thyroid autoimmunity were exclusion criteria. Body composition and muscle cross-sectional area were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Total (triiodothyronine (T(3); TT(3)) thyroxine and (T(4); TT(4))) and free thyroid hormones (FT(3) and FT(4)), TSH, and reverse T(3) (rT(3)) and thyroid-binding globulin (TBG) were determined using immunoassays. RESULTS: BMI was positively associated with (F)T(3) (P<0.0001). Whole body fat mass displayed positive associations with TT(3) and with (F)T(4) and TBG (P≤0.0006). Positive associations were further observed between leptin and (F)T(3), TT(4), and TBG (P≤0.0002). Inverse associations between lean mass and muscle cross-sectional area and (F)T(3), (F)T(4), and TBG were observed (P≤0.0003). Higher levels of (F)T(3) and TBG were associated with lower insulin sensitivity, assessed by homeostatic model assessment of insulin resistance (IR; P≤0.0001). No associations between TSH and body composition or metabolic parameters were seen. CONCLUSION: We show that a less favorable body composition (with higher fat and lower muscle mass and accompanying higher leptin concentrations) and IR are associated with higher thyroid hormone levels in healthy young men with well characterized euthyroidism.

Comparative bone status assessment by dual energy X-ray absorptiometry, peripheral quantitative computed tomography and quantitative ultrasound in adolescents and young adults with cystic fibrosis.

PURPOSE: Quantitative ultrasound bone sonometry (QUS) might be a promising screening method for cystic fibrosis (CF)-related bone disease, given its absence of radiation exposure, portability of the equipment and low cost.The value of axial transmission forearm QUS in detecting osteopenia in CF was therefore studied. METHODS: We investigated the application of QUS in the evaluation of bone status in a group of 64 adolescents (>12 years) and young adults (<40 years) with CF in a comparison with a dual X-ray absorptiometry (DXA) of the whole body and peripheral quantitative computed tomography (pQCT) of the radius at 4% and 66% sites. RESULTS: Mean (SD) Z-scores of speed of sound (SOS), whole body bone mineral content (BMC), radial trabecular bone mineral density (BMD), and radial cortical BMD were respectively -0.31 (0.78), -0.09 (1.28), 0.10 (1.16) and -0.62 (2.88). The pQCT determined bone geometry values (cortical bone area and cortical thickness) were more depressed than the BMD data. QUS had a sensitivity and specificity of respectively 0% and 96% for diagnosing osteopenia (based on a whole body BMC Z-score<-2). CONCLUSIONS: QUS cannot replace DXA, but can screen out patients with normal bone mass. Further and larger studies are needed to examine if QUS may reflect other aspects than bone mass, or if it is possible to improve its sensitivity by supplementing the SOS results with clinical risk factors.

Bivariate association analysis in selected samples: application to a GWAS of two bone mineral density phenotypes in males with high or low BMD.

Our specific aims were to evaluate the power of bivariate analysis and to compare its performance with traditional univariate analysis in samples of unrelated subjects under varying sampling selection designs. Bivariate association analysis was based on the seemingly unrelated regression (SUR) model that allows different genetic models for different traits. We conducted extensive simulations for the case of two correlated quantitative phenotypes, with the quantitative trait locus making equal or unequal contributions to each phenotype. Our simulation results confirmed that the power of bivariate analysis is affected by the size, direction and source of the phenotypic correlations between traits. They also showed that the optimal sampling scheme depends on the size and direction of the induced genetic correlation. In addition, we demonstrated the efficacy of SUR-based bivariate test by applying it to a real Genome-Wide Association Study (GWAS) of Bone Mineral Density (BMD) values measured at the lumbar spine (LS) and at the femoral neck (FN) in a sample of unrelated males with low BMD (LS Z-scores ≤ -2) and with high BMD (LS and FN Z-scores >0.5). A substantial amount of top hits in bivariate analysis did not reach nominal significance in any of the two single-trait analyses. Altogether, our studies suggest that bivariate analysis is of practical significance for GWAS of correlated phenotypes.

Anthropometric and skeletal phenotype in men with idiopathic osteoporosis and their sons is consistent with deficient estrogen action during maturation.

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.

Body composition, volumetric and areal bone parameters in male-to-female transsexual persons.

CONTEXT: Male-to-female (M-->F) transsexual persons undergo extreme changes in gonadal hormone concentrations, both by pharmacological and surgical interventions. Given the importance of sex steroids for developing and maintaining bone mass, bone health is a matter of concern in daily management of these patients. OBJECTIVE: To provide data on bone metabolism, geometry and volumetric bone mineral density in M-->F transsexual persons. DESIGN/SETTING/PARTICIPANTS: Twenty-three M-->F transsexual persons, recruited from our gender dysphoria clinic and at least 3 yrs after sex reassignment surgery, together with 46 healthy age- and height-matched control men were included in this cross-sectional study. MAIN OUTCOME MEASURES: Body composition, areal and volumetric bone parameters determined using DXA and peripheral quantitative computed tomography. Hormone levels and markers of bone metabolism assessed using immunoassays. Peak torque of biceps and quadriceps muscles and grip strength assessed using an isokinetic and hand dynamometer, respectively. RESULTS: M-->F transsexual persons presented lower total and regional muscle mass and lower muscle strength as compared to controls (all P<0.001). In addition, they had higher total and regional fat mass (P<0.010) and a lower level of sports-related activity index (P<0.010). Bone mineral content and areal density (aBMD) of the lumbar spine, total hip and distal radius, as well as trabecular vBMD of the distal radius was lower as compared to controls (P<0.010). At cortical sites, no differences in cortical vBMD were observed, whereas M-->F transsexual persons were characterized by smaller cortical bone size at both the radius and tibia (P<0.010). Lower levels of biochemical markers of bone formation and resorption (P<0.010) suggested decreased bone turnover. CONCLUSION: M-->F transsexual persons have less lean mass and muscle strength, and higher fat mass. In addition, they present lower trabecular vBMD and aBMD at the lumbar spine, total hip and distal radius, and smaller cortical bone size as compared to matched controls. Both the lower level of sports-related physical activity as well testosterone deprivation could contribute to these findings. These results indicate that bone health should be a parameter of interest in the long-term follow-up care for M-->F transsexual persons.