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Kinetics of removal of intravenous testosterone pulses in normal men.

ABSTRACT: Testosterone is secreted into the bloodstream episodically, putatively distributing into total, bioavailable (bio) nonsex hormone-binding globulin (nonSHBG-bound), and free testosterone moieties. The kinetics of total, bio, and free testosterone pulses are unknown. Design Adrenal and gonadal steroidogenesis was blocked pharmacologically, glucocorticoid was replaced, and testosterone was infused in pulses in four distinct doses in 14 healthy men under two different paradigms (a total of 220 testosterone pulses).Testosterone kinetics were assessed by deconvolution analysis of total, free, bioavailable, SHBG-bound, and albumin-bound testosterone concentration-time profiles.Independently of testosterone dose or paradigm, rapid-phase half-lives (min) of total, free, bioavailable, SHBG-bound, and albumin-bound testosterone were comparable at 1.4+/-0.22 min (grand mean+/-S.E.M. of geometric means). Slow-phase testosterone half-lives were highest for SHBG-bound testosterone (32 min) and total testosterone (27 min) with the former exceeding that of free testosterone (18 min), bioavailable testosterone (14 min), and albumin-bound testosterone (18 min; P<0.001). Collective outcomes indicate that i) the rapid phase of testosterone disappearance from point sampling in the circulation is not explained by testosterone dose; ii) SHBG-bound testosterone and total testosterone kinetics are prolonged; and iii) the half-lives of bioavailable, albumin-bound, and free testosterone are short.A frequent-sampling strategy comprising an experimental hormone clamp, estimation of hormone concentrations as bound and free moieties, mimicry of physiological pulses, and deconvolution analysis may have utility in estimating the in vivo kinetics of other hormones, substrates, and metabolites.

SUBMITTER: Veldhuis JD

PROVIDER: S-EPMC2861557 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

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Kinetics of removal of intravenous testosterone pulses in normal men.

Veldhuis Johannes D JD Keenan Daniel M DM Liu Peter Y PY Takahashi Paul Y PY

European journal of endocrinology 20100120 4

<h4>Background</h4>Testosterone is secreted into the bloodstream episodically, putatively distributing into total, bioavailable (bio) nonsex hormone-binding globulin (nonSHBG-bound), and free testosterone moieties. The kinetics of total, bio, and free testosterone pulses are unknown. Design Adrenal and gonadal steroidogenesis was blocked pharmacologically, glucocorticoid was replaced, and testosterone was infused in pulses in four distinct doses in 14 healthy men under two different paradigms (a ...[more]

PMID: 20089549

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Project description:INTRODUCTION:Hypersexual disorder as suggested to be included in the Diagnostic and Statistical Manual of Mental Disorders-5 integrates aspects of sexual desire deregulation, impulsivity, and compulsivity. However, it is unknown how it affects gonadal activity and the function of the hypothalamus-pituitary-gonadal (HPG) axis. AIM:The aim of this study was to investigate testosterone and luteinizing hormone (LH) levels in hypersexual men compared with healthy controls. Furthermore, we investigated associations between epigenetic markers and hormone levels. METHODS:Basal morning plasma levels of testosterone, LH, and sex hormone-binding globulin (SHBG) were assessed in 67 hypersexual men (mean age: 39.2 years) compared with 39 age-matched healthy controls (mean age: 37.5 years). The Sexual Compulsivity Scale and the Hypersexual Disorder: Current Assessment Scale were used for assessing hypersexual behavior, the Montgomery-Åsberg Depression Scale-self rating was used for depression severity, and the Childhood Trauma Questionnaire (CTQ) was used for assessing history of childhood adversity. The genome-wide methylation pattern of more than 850 K CpG sites was measured in whole blood using the Illumina Infinium Methylation EPIC BeadChip. CpG sites located within 2,000 bp of the transcriptional start site of hypothalamus pituitary adrenal (HPA) and HPG axis-coupled genes were included. MAIN OUTCOME MEASURES:Testosterone and LH plasma levels in association with clinical rating and a secondary outcome was the epigenetic profile of HPA and HPG axis-coupled CpG sites with testosterone and LH levels. RESULTS:LH plasma levels were significantly higher in patients with hypersexual disorder than in healthy volunteers. No significant differences in plasma testosterone, follicle stimulating hormone, prolactin, and SHBG levels were found between the groups. There were no significant associations between DNA methylation of HPA and HPG axis-coupled genes and plasma testosterone or LH levels after multiple testing corrections. CONCLUSIONS:Subtle dysregulation of the HPG axis, with increased LH plasma levels but no difference in testosterone levels may be present in hypersexual men. Chatzittofis A, Boström AE, Öberg KG, et al. Normal Testosterone but Higher Luteinizing Hormone Plasma Levels in Men With Hypersexual Disorder. Sex Med 2020;8:243-250.

Project description:Background The prevalence of low testosterone levels in men increases with age, as does the prevalence of decreased mobility, sexual function, self-perceived vitality, cognitive abilities, bone mineral density, and glucose tolerance, and of increased anemia and coronary artery disease. Similar changes occur in men who have low serum testosterone concentrations due to known pituitary or testicular disease, and testosterone treatment improves the abnormalities. Prior studies of the effect of testosterone treatment in elderly men, however, have produced equivocal results. Purpose To describe a coordinated set of clinical trials designed to avoid the pitfalls of prior studies and to determine definitively whether testosterone treatment of elderly men with low testosterone is efficacious in improving symptoms and objective measures of age-associated conditions. Methods We present the scientific and clinical rationale for the decisions made in the design of this set of trials. Results We designed The Testosterone Trials as a coordinated set of seven trials to determine if testosterone treatment of elderly men with low serum testosterone concentrations and symptoms and objective evidence of impaired mobility and/or diminished libido and/or reduced vitality would be efficacious in improving mobility (Physical Function Trial), sexual function (Sexual Function Trial), fatigue (Vitality Trial), cognitive function (Cognitive Function Trial), hemoglobin (Anemia Trial), bone density (Bone Trial), and coronary artery plaque volume (Cardiovascular Trial). The scientific advantages of this coordination were common eligibility criteria, common approaches to treatment and monitoring, and the ability to pool safety data. The logistical advantages were a single steering committee, data coordinating center and data and safety monitoring board, the same clinical trial sites, and the possibility of men participating in multiple trials. The major consideration in participant selection was setting the eligibility criterion for serum testosterone low enough to ensure that the men were unequivocally testosterone deficient, but not so low as to preclude sufficient enrollment or eventual generalizability of the results. The major considerations in choosing primary outcomes for each trial were identifying those of the highest clinical importance and identifying the minimum clinically important differences between treatment arms for sample size estimation. Potential limitations Setting the serum testosterone concentration sufficiently low to ensure that most men would be unequivocally testosterone deficient, as well as many other entry criteria, resulted in screening approximately 30 men in person to randomize one participant. Conclusion Designing The Testosterone Trials as a coordinated set of seven trials afforded many important scientific and logistical advantages but required an intensive recruitment and screening effort.

Project description:Abstract BACKGROUND: In men, obesity is often associated with low testosterone (T) levels, but information is limited as to how body weight affects the pharmacokinetic profile or dosing of testosterone therapy (TTh) in men with T deficiency. Historically, men with body mass index (BMI) >32.4 kg/m2 required higher doses of T 2% gel to achieve physiological T levels than men with BMI ≤29.1 or 29.2–32.4 kg/m2.(1) In a phase 3 trial (N=150) of subcutaneous (SC) testosterone enanthate (TE) administered weekly, concentration-guided dosing raised T levels to within physiological range in 92.7% of patients.(2) Here, we report a post hoc analysis evaluating the association between body weight and serum T levels attained with SC TE. Methods: SC TE was evaluated in an open-label, single-arm, dose-blinded, 52-week phase 3 trial (NCT02159469). Patients self-administered 75 mg SC TE weekly during the titration phase; blinded dose-adjustments in 25 mg increments occurred at pre-defined time points beyond the sixth dose. The primary endpoint of this study was the percentage of patients achieving an average serum T concentration (Cavg0-168h) of 300 to 1,100 ng/dL at week 12. For this post hoc analysis, a linear regression model with weight and dose as independent variables was used to assess differences in mean minimum T concentration (Cmin) and Cavg0-168h at week 12. Results: For this analysis, 137 patients were included. Doses were 50 mg (n=25), 75 mg (n=93), and 100 mg (n=19). The mean weight was 84.4 kg, 102.2 kg, and 112.0 kg for the 50 mg, 75 mg, and 100 mg dose groups, respectively (range, 49.9–146.5 kg). The dose-normalized T Cmin was 9.2 ng/dL, 5.7 ng/dL, and 4.3 ng/dL per 1 mg of SC TE for the 50 mg, 75 mg, and 100 mg groups, respectively. The dose-normalized T Cavg0-168h was 12.0 ng/dL, 7.2 ng/dL, and 5.7 ng/dL per 1 mg of SC TE. In an overall linear regression model, 48.2% (P<0.0001) and 55.0% (P<0.0001) of the total variance in Cmin and Cavg0-168h, respectively, can be predicted from the independent weight and dose variables. Conclusion: Our results show an inverse relationship between body weight and T exposure. Men with higher mean body weights required higher doses of SC TE to achieve physiologic T levels compared with men with lower mean body weights. The available doses provide effective options to reach target exposures. These findings highlight the impact of weight and dose selection on SC TE exposure. References: (1) Dobs et al., J Sex Med 2014;11:857–864; (2) Kaminetsky et al., J Urol. 2019;201:587–94.

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Kinetics of removal of intravenous testosterone pulses in normal men.

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Kinetics of removal of intravenous testosterone pulses in normal men.

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