Population Of Healthy Men Research Articles

Smoking and combined oral contraceptives should be considered as an independent variable in sex and gender-oriented studies

The influence of sex combined with smoking and combined oral contraceptives (COC) use on atherogenic indexes is scarcely studied. Thus, traditional lipid parameters were measured, and non-traditional atherogenic indexes were calculated in a young and healthy population of men, COC-free women, and COC users.Total cholesterol (TChol), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and HDL/LDL ratio were lower in men, while triglycerides (TG)/HDL ratio, atherogenic index of plasma (AIP), Castelli's Risk Index I (CRII) and CRI-II, atherogenic coefficient (AC), creatinine, creatinine clearance, and estimated glomerular filtration rate (eGFR) were higher in men. The use of COC modified TChol, HDL, TG, TG/HDL, and AIP which had significantly higher values in COC users. In addition, TG were also increased in COC users in comparison with men.Smoking reduced sexually divergent parameters: BMI, TG, HDL/LDL, TG/HDL, AIP, CRII, CRI-II, and AC became similar among the three cohorts, losing the reported sex differences.Smoking also reduced differences in TChol, HDL, TG, and AIP between COC-free women and COC users, but it does not affect CRII, CRI-II, creatinine, creatinine clearance, and eGFR, underlining that COC users and COC-free women have to be considered two different populations.Our results represent a complex landscape suggesting that for both sexes smoking should be an independent variable in medical studies. Moreover, in women, the use of COC evidenced two different cohorts. Thus, more variables should be considered during a single study indicating that sex, smoking, and COC should be studied together to get a picture of the real-life context.

Can Injuries Have a Lasting Effect on the Perception of Pain in Young, Healthy Women and Men?

Pain is a characteristic, unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is a subjective sensation, modulated by many factors such as age, sex, emotional state, national origin, or physical activity. Moreover, it is closely associated with intense physical activity, injuries, and traumas, which can significantly modulate pain tolerance. We postulate that there are correlations between past injuries, physical activity, and intensity of pain perception (pain threshold and pain tolerance) in a population of healthy men and women. Retrospective cohort study. Level 4. A total of 302 participants aged 18 to 32 years were included. The participants were divided into 2 groups (active and inactive individuals), in accordance with the scope of physical activity they had indicated. The test of pressure pain threshold and pressure pain tolerance was performed using an algometer. Active women achieved significantly higher pain threshold and pain tolerance values in all measurements on the upper limb (except for the pain threshold on the left hand) compared with inactive women. In mediation analysis, the effect of injury remained significant only for the pressure pain tolerance in the dominant arm and the left hand in the female group. In the case of men, there were no significant differences in all measurements in view of the threshold and tolerance for pain between the groups of active and inactive and between men with injuries and without injuries. Intense, regular physical activity is a factor modulating the perception of pain. This was demonstrated as lowered sensitivity to pain stimuli in a population of healthy women. Injuries should be treated as an important factor modulating the perception of pain. We recommend detailed monitoring of injuries during treatment and control of pain sensation.

Waddlia chondrophila and Male Infertility.

Waddlia chondrophila, a Chlamydia-like bacterium, has been previously associated with adverse pregnancy outcomes. Analogously to Chlamydia trachomatis, W. chondrophila also negatively impacts human semen and may be a source of impaired male fertility. In this study, we analyzed W. chondrophila seroprevalence in a population of male patients of infertile couples and the impact of past exposition to this bacterium on semen parameters. Our results show a surprisingly high seroprevalence of W. chondrophila, which contrasts with a previous study focusing on a population of healthy men. Nevertheless, we did not observe any significant association between positive serology and abnormal sperm parameters. This may suggest that a negative impact on semen is observed only during an ongoing infection. Alternatively, W. chondrophila may have an immune impact on male fertility, as previously postulated for women with adverse pregnancy outcomes.

Evaluation of a Rapid Assessment Questionnaire Using a Biomarker for Dietary Intake of n-3 Fatty Acids.

While there is considerable evidence supporting health benefits of consuming diets high in omega-3 (n-3) fatty acids, there is no quick and effective tool to measure n-3 intake. The objective of this study was to evaluate the accuracy of a rapid assessment questionnaire (the Omega-3 Checklist) used to quantify intake of n-3 fatty acids. This was done by comparing n-3 intakes to blood biomarkers of n-3 exposure in a population of healthy men and women. In addition, a separate analysis was run including covariates age, sex, and weight, which have been shown to affect n-3 biomarker levels. Reported intake of eicosapentaenoic acid (EPA), docoshexaenoic acid (DHA), and EPA + DHA was correlated with erythrocyte EPA (Spearman's rank correlation rs = 0.51, p < 0.001), DHA (rs = 0.54, p < 0.001), and the Omega-3 Index (rs = 0.57, p < 0.001). These associations remained significant when controlling for age, sex, and weight. Therefore, the Omega-3 Checklist can be a useful, rapid assessment tool to estimate individuals' EPA and DHA intake.

The risk factors for cardiovascular disease and the vascular age of the population of healthy men are 40 to 60 years

The risk factors for cardiovascular disease and the vascular age of the population of healthy men are 40 to 60 years

Neuroticism and stress: the role of displacement behavior

Background and Objectives: Neuroticism is linked with an impaired ability to cope with stress and is an important risk factor for stress-related disorders. Hence, there is interest in exploring the behavioral correlates of neuroticism and how such behaviors may moderate the link between neuroticism and the response to stress. Displacement behavior – activity such as face touching and scratching – is important to investigate in this respect, as recent studies indicate that such behavior is linked to negative emotional states and has an important stress coping function. Here, we explored the relationship between neuroticism, displacement behavior, and stress in a healthy population of men. Design: This was a cross-sectional, quasiexperimentally controlled study. Methods: We assessed participants' levels of neuroticism, and then during a Trier Social Stress Test quantified displacement behavior, physiological, and cognitive indices of the stress response; after the test we measured the self-reported experience of stress. Results: Displacement behavior was negatively correlated with self-reported experience, physiological, and cognitive measures of stress and moderated the relationships between neuroticism, self-reported experience, and cognitive index of stress. Conclusions: Our results suggest displacement behavior plays an important role in shaping the link between neuroticism and the response to stress.

Influence of serological factors and BMI on the blood pressure/hematocrit association in healthy young men and women.

The association between mean arterial blood pressure (MAP) and hematocrit (Hct) as a surrogate for blood viscosity was investigated in a young (average 20.0±2.3 years), healthy population of 174 men and 442 women. Health status was assessed by clinical examination and serological evaluation. Individuals with severe anemia or hemoconcentration, prior traumas or major surgical intervention, smokers, and pregnant or lactating women were excluded from the study. The MAP/Hct association was positive and significant (P=0.04) for women and negative, albeit not significantly so, for men. The MAP/Hct association was also evaluated in subgroups of the same population with a progressive step-by-step exclusion of: individuals with cholesterol >200 mg/dL; triglycerides >200 mg/dL; body mass index >25 kg/m2; and glucose >100 mg/dL. This consecutively reduced the strength of the positive MAP/Hct association in women, which became negative – although not significantly so – when all anomalously high factors were excluded. The same trend was found in men. Our study indicates that previously reported positive trends in the relationship between the MAP and Hct in the population are not present in a young, healthy population of men or women that excludes individuals with the confounding factors of above normal serological values and BMI.

PD26-07 COMPARISON OF PATIENTS UNDERGOING PHOTOVAPORIZATION OF THE PROSTATE VERSUS TRANSURETHRAL RESECTION OF THE PROSTATE

You have accessJournal of UrologyBenign Prostatic Hyperplasia: Surgical Therapy & New Technology I1 Apr 2014PD26-07 COMPARISON OF PATIENTS UNDERGOING PHOTOVAPORIZATION OF THE PROSTATE VERSUS TRANSURETHRAL RESECTION OF THE PROSTATE Rena Malik, Chi-Hsiung Wang, Brittany Lapin, and Brian T. Helfand Rena MalikRena Malik More articles by this author , Chi-Hsiung WangChi-Hsiung Wang More articles by this author , Brittany LapinBrittany Lapin More articles by this author , and Brian T. HelfandBrian T. Helfand More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2094AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The introduction of laser therapies for the management of bladder outlet obstruction in men with benign prostatic hypertrophy (BPH) has allowed the urologist to treat patients previously thought to be poor candidates for standard transurethral resection of the prostate (TURP). We sought to compare the changing clinical characteristics of patients undergoing TURP and photovaporization of the prostate (PVP) over time. METHODS The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for men who underwent TURP and PVP from 2005-2012. Patient demographics, clinical characteristics, and 30-day postoperative outcomes were analyzed. RESULTS 12,670 men met inclusion criteria. 65% (8259) underwent TURP and 35% (4411) underwent PVP. There were significant differences in the overall demographic and clinical characteristics between groups including age, race and co-morbidities (Table 1). Those undergoing TURP were more likely to be scheduled as an emergency (3% vs. 1%, p<.01), have shorter operative times (53 vs. 56 min, p<.01), longer hospital stays (2.4 vs. 1.0 days, p<.01), more frequent blood transfusions (2.1% vs. 0.6%, p<.01), and more postoperative complications including: pneumonia (0.5% vs. 0.3%, p=0.02), septic shock (0.3% vs. 0.1%, p=0.045), and re-operation within 30 days (2.2% vs. 1.4%, p<.01). However, between 2007 and 2012, men undergoing TURP had increased functional independence (93% to 96%, p<.001), ASA Physical Class I (0.6% to 5.1%, p<.001), as well as less hypertension (68% to 59%, p<.001). In contrast, men undergoing PVP over the same time period showed an increase in co-morbidities including increased mean age (71 years to 73 years, p<.001), a higher frequency of use in emergency cases (0.8% to 2.4%, p<.01), and an increase in mean length of hospital stay (0.50 days to 1.30 days, p=.048). CONCLUSIONS Statistically significant differences in clinical characteristics of patients undergoing TURP and PVP have historically existed. However, since 2007 the use of PVP has expanded to include an older and less healthy population of men. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e761-e762 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Rena Malik More articles by this author Chi-Hsiung Wang More articles by this author Brittany Lapin More articles by this author Brian T. Helfand More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A flow cytometric method for characterization of circulating cell-derived microparticles in plasma

Background and aimPrevious studies on circulating microparticles (MPs) indicate that the majority of MPs are of a size below the detection limit of most standard flow cytometers. The objective of the present study was to establish a method to analyze MP subpopulations above the threshold of detection of a new generation BD FACSAria™ III digital flow cytometer.MethodsWe analyzed MP subpopulations in plasma from 24 healthy individuals (9 males and 15 females). MPs were identified according to their size (<1.0-µm), by Lactadherin-FITC labelling, and by exposure of cell-specific markers. The sensitivity of the flow cytometer was tested against that of a previous-generation instrument FC500. Reproducibility of the FACSAria and our set-up was investigated, and the percentage of phosphatidylserine (PS) exposing MPs binding Lactadherin was determined.ResultsBy using a flow cytometric approach we identified and quantitated MPs derived from platelets, monocytes, erythrocytes and endothelial cells. In addition, levels of tissue factor-positive MPs were determined. The FACSAria demonstrated improved sensitivity and increased MP detection range compared to the FC500 instrument. The reproducibility of PS+PMP and PS+MP measurements was 11.7 and 23.2%, respectively. When expressed as a percentage of total MPs, the PS-positive MP population represented 15.1±5.5%, and PS-positive MPs were significantly increased in men.ConclusionWe have established a method to measure MPs above the detection limit of a new generation flow cytometer and derived from a number of cell-types in a healthy population of men and women.

The Energy Balance Study: The Design and Baseline Results for a Longitudinal Study of Energy Balance

Purpose: The Energy Balance Study (EBS) was a comprehensive study designed to determine over a period of 12 months the associations of caloric intake and energy expenditure on changes in body weight and composition in a population of healthy men and women. Method: EBS recruited men and women aged 21 to 35 years with a body mass index between 20 and 35 kg/m2. Measurements of energy intake and multiple objective measures of energy expenditure, as well as other physiological, anthropomorphic and psychosocial measurements, were made quarterly. Resting metabolic rate and blood chemistry were measured at baseline, 6 and 12 months. Results: Four hundred and thirty (218 women and 212 men) completed all baseline measurements. There were statistically significant differences by sex uncovered for most anthropomorphic, physiological and behavioral variables. Only percent of kcals from fat and alcohol intake, as well as energy expenditure in light activity and very vigorous activity were not different. Self-reported weight change (mean ± SD) over the previous year were 0.92 ± 5.24 kg for women and − 1.32 ± 6.1 kg for men. Resting metabolic rate averages by sex were 2.88 ± 0.35 ml/kg/min for women and 3.05 ± 0.33 ml/kg/min for men. Conclusion: Results from EBS will inform our understanding of the impact of energy balance components as they relate to changes in body weight and composition. Initial findings suggest a satisfactory distribution of weight change to allow for robust statistical analyses. Resting metabolic rates well below the standard estimate suggest that the evaluation of the components of total energy expenditure will be impactful for our understanding of the roles of energy intake and expenditure on changes in energy utilization and storage.

Displacement behaviour is associated with reduced stress levels among men but not women.

Sex differences in the ability to cope with stress may contribute to the higher prevalence of stress-related disorders among women compared to men. We recently provided evidence that displacement behaviour - activities such as scratching and face touching - represents an important strategy for coping with stressful situations: in a healthy population of men, displacement behaviour during a social stress test attenuated the relationship between anxiety experienced prior to this test, and the subsequent self-reported experience of stress. Here, we extend this work to look at physiological and cognitive (in addition to self-reported) measures of stress, and study both men and women in order to investigate whether sex moderates the link between displacement behaviour and the response to stress. In a healthy study population, we quantified displacement behaviour, heart rate and cognitive performance during the Trier Social Stress Test, and used self-report questionnaires to assess the experience of stress afterwards. Men engaged in displacement behaviour about twice as often as women, and subsequently reported lower levels of stress. Bivariate correlations revealed that for men, higher rates of displacement behaviour were associated with decreased self-reported stress, fewer mistakes in the cognitive task and a trend towards lower heart rate; no relationships between displacement behaviour and stress measures were found for women. Moreover, moderation analyses revealed that high rates of displacement behaviour were associated with lower stress levels in men but not in women, and that high displacement behaviour rates were associated with poorer cognitive performance in women, but not men. These results point to an important sex difference in coping strategies, and highlight new avenues for research into sex biases in stress-related disorders.

Physical activity and television watching in relation to semen quality in young men

BackgroundSemen quality appears to have declined over the past decades but reasons for this decline are unresolved. The concurrent increase in sedentary behaviour may be a contributing factor. The objective...

SVM Method used to Study Gender Differences Based on Microelement

Abstract [objective] Intelligent Algorithm of SVM is used for studying gender differences based on microelement data, which provide reference For the application of Microelement in healthy people, such as providing technical support for the investigation of cases.[Method] Our Long-term test results on hair microelement of health people were consolidated. Support vector machine (SVM) is used to classified model of male and female based on microelement data. The radical basis function (RBF) is adopted as a kernel function of SVM, and the model adjusts C and σ to build the optimization classifier, [Result] Healthy population of men and women of manganese, cadmium and nickel are quite different, The classified model of Microelement based on SVM can classifies the male and female, the correct classification ratio set to be 81.71% and 66.47% by SVM based on 7 test date and 3 test data selection. [conclusion] The classified model of microelement data based on SVM can classifies male and female.

Evaluation of arterial propagation velocity based on the automated analysis of the Pulse Wave Shape

This paper proposes the automatic estimation of the arterial propagation velocity from the pulse wave raw records measured in the region of the radial artery. A fully automatic process is proposed to select and analyze typical pulse cycles from the raw data. An adaptive neuro-fuzzy inference system, together with a heuristic search is used to find a functional approximation of the pulse wave. The estimation of the propagation velocity is carried out via the analysis of the functional approximation obtained with the fuzzy model. The analysis of the pulse wave records with the proposed methodology showed small differences compared with the method used so far, based on a strong interaction with the user. To evaluate the proposed methodology, we estimated the propagation velocity in a population of healthy men from a wide range of ages. It has been found in these studies that propagation velocity increases linearly with age and it presents a considerable dispersion of values in healthy individuals. We conclude that this process could be used to evaluate indirectly the propagation velocity of the aorta, which is related to physiological age in healthy individuals and with the expectation of life in cardiovascular patients.

Estimating V˙O2peak from a Nonexercise Prediction Model

Cardiorespiratory fitness is suggested to be an important marker of cardiovascular risk but is rarely evaluated in health care settings. In the present study, directly measured peak oxygen uptake (V·O 2peak) from a diverse population of 4637 healthy participants were used to develop and cross-validate a new nonexercise regression model of cardiorespiratory fitness for men and women. Multivariable regression analysis was used to develop a nonexercise model of cardiorespiratory fitness for men and women separately with V·O 2peak as the outcome. In the final models, 2067 men (mean age = 48.8 yr) and 2193 women (mean age = 47.9 yr) were included, respectively. Cross-validation of the models was done by standard data splitting procedures with evaluation of constant error and total error of a model developed on one sample and cross-validated on another sample. Age, waist circumference, leisure time physical activity, and resting HR, successively, were the most potent predictors of V·O 2peak for both men and women. Together, 61% and 56% of variance in V·O 2peak, for men and women, respectively, were explained by the full models. SEE was 5.70 and 5.14 for the models including men and women, respectively. The nonexercise regression model developed in the present study was fairly accurate in predicting V·O 2peak in this healthy population of men and women. The model might be generalized to other healthy populations and might be a valid tool for a rough assessment of cardiorespiratory fitness in an outpatient setting.

Impact of Body Mass Index, Physical Activity, and Other Clinical Factors on Cardiorespiratory Fitness (from the Cooper Center Longitudinal Study)

Cardiorespiratory fitness (CRF) is widely accepted as an important reversible cardiovascular risk factor. In the present study, we examined the nonmodifiable and modifiable determinants of CRF within a large healthy Caucasian population of men and women. The study included 20,239 patients presenting to Cooper Clinic (Dallas, Texas) for a comprehensive medical examination from 2000 through 2010. CRF was determined by maximal treadmill exercise testing. Physical activity categories were 0 metabolic equivalent tasks (METs)/min/week (no self-reported moderate or vigorous intensity physical activity), 1 to 449 METs/min/week (not meeting physical activity guideline), 450 to 749 METs/min/week (meeting guideline), and ≥750 METs/min/week (exceeding guideline). Linear regression modeling was used to determine the most robust clinical factors associated with achieved treadmill time. Age, gender, body mass index (BMI), and physical activity were the most important factors associated with CRF, explaining 56% of the variance (R(2) = 0.56). The addition of all other factors combined (current smoking, systolic blood pressure, blood glucose, high-density and low-density lipoprotein cholesterol, health status) were associated with CRF (p <0.05) but additively only improved R(2) by 2%. There was a significant interaction between BMI and physical activity on CRF, such that normal-weight (BMI <25 kg/m(2)) subjects achieved higher CRF for a given level of physical activity compared to obese subjects (BMI ≥30 kg/m(2)). Percent body fat, not lean body mass, was the key factor driving this interaction. In conclusion, BMI was the most important clinical risk factor associated with CRF other than nonmodifiable risk factors age and gender. For a similar amount of physical activity, normal-weight subjects achieved a higher CRF level compared to obese subjects. These data suggest that obesity may offset the benefits of physical activity on achieved CRF, even in a healthy population of men and women.

A Nutrient Approach to Prostate Cancer Prevention: The Selenium and Vitamin E Cancer Prevention Trial (SELECT)

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) randomized 35,533 healthy men, >55 yr old (>50 yr if African American), with normal digital rectal exams and prostate specific antigens <4 ng/ml to 1) 200 μg/day l-selenomethionine, 2) 400 IU/day all-rac-alpha-tocopheryl acetate (vitamin E), 3) both supplements, or 4) placebo for 7 to 12 yr. The hypotheses underlying SELECT, that selenium and vitamin E individually and together decrease prostate cancer incidence, derived from epidemiologic and laboratory evidence and significant secondary endpoints in the Nutritional Prevention of Cancer (selenium) and Alpha-Tocopherol Beta-Carotene (vitamin E) trials. In SELECT, prostate cancer incidence did not differ among the 4 arms: hazard ratios [99% confidence intervals (CIs)] for prostate cancer were 1.13 (99% CI = 0.95–1.35, P = 0.06; n = 473) for vitamin E, 1.04 (99% CI = 0.87–1.24, P = 0.62; n = 432) for selenium, and 1.05 (99% CI = 0.88–1.25, P = 0.52; n = 437) for selenium + vitamin E vs. 1.00 (n = 416) for placebo. Statistically nonsignificant increased risks of prostate cancer with vitamin E alone [relative risk (RR) = 1.13, P = 0.06) and newly diagnosed Type 2 diabetes mellitus with selenium alone (RR = 1.07, P = 0.16) were observed. SELECT data show that neither selenium nor vitamin E, alone or together, in the doses and formulations used, prevented prostate cancer in this heterogeneous population of healthy men.

Growth hormone secretion in response to glucagon stimulation test in healthy middle-aged men

To investigate the growth hormone (GH) response to glucagon stimulation test (GST) in a population of healthy men over 50 years old in comparison to insulin tolerance test (ITT), analysis of the spontaneous 24-hour GH profile and insulin-like growth factor 1 (IGF-I). 27 healthy men aged between 51 and 65 years were tested. Using non-parametric correlation analysis, a positive correlation between GH peak after GST and mean IGF-I (r = 0.528; p = 0.005) was found, as well with GH peak in 24-hour profile (r = 0.494; p = 0.009). No correlation was found comparing GH peak after ITT with the same parameters. Ten subjects presented GH peak of less than 3.0 microg/L after GST, none confirmed in ITT. GH peak response to GST was lower than ITT, but it showed a positive correlation with mean IGF-I and also with GH peak in 24-hour profile. However, GST should not be used to differentiate organic growth hormone deficiency (GDH) from the expected decline on GH secretion due to aging.

Serum Estradiol Is Associated With Volumetric BMD and Modulates the Impact of Physical Activity on Bone Size at the Age of Peak Bone Mass: A Study in Healthy Male Siblings

This study investigates determinants of peak bone mass (PBM) in healthy men, focusing on effects and interactions of parameters reflecting mechanical loading and sex steroids. Healthy male siblings (n = 677; 25-45 yr) were recruited in a cross-sectional, population-based study. Physical activity score was assessed by a self-reported questionnaire. Cross-sectional muscle area (CSMA) and bone parameters of radius (4% and 66% site) and tibia (66% site) were assessed using pQCT. Peak torque of biceps and quadriceps muscles was assessed by isokinetic dynamometry. Serum testosterone (T) and estradiol (E(2)) levels were measured using immunoassays; free hormone fractions were calculated. Relations between indices of bone strength, CSMA, muscle strength, and sex steroids were studied using linear mixed-effects modeling. Physical activity, CSMA, and muscle strength were positively associated with indices of bone strength, except for volumetric BMD (vBMD). After controlling for age, weight, and height, free E(2) levels were positively associated with trabecular and cortical vBMD, negatively associated with endosteal circumference at the radius, and positively associated with cortical vBMD at the tibia. In addition, positive interactions between physical activity and serum E(2) concentrations were observed for bone size at the tibia. No associations between free T levels and pQCT bone parameters were found. In this population of healthy men at the age of PBM, parameters reflecting mechanical loading are confirmed as important determinants of bone size. E(2), but not T, levels are positively associated with vBMD and modulate the impact of physical activity on bone size at the tibia.

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

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. 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. 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. 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.