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Testosterone : an unauthorized biography
Testosterone is a familiar villain, a ready explanation for innumerable social ills, from the stock market crash and the overrepresentation of men in prisons to male dominance in business and politics. It's a lot to pin on a simple molecule. Yet your testosterone level doesn't in fact predict your competitive drive or tendency for violence, your appetite for risk or sex, or your strength or athletic prowess. It's neither the biological essence of manliness nor even \"the male sex hormone.\" This unauthorized biography pries T, as it's known, loose from over a century of misconceptions that undermine science even as they make urban legends about this hormone seem scientific. T's story didn't spring from nature: it is a tale that began long before the hormone was even isolated, when nineteenth-century scientists went looking for the chemical essence of masculinity. And so this molecule's outmoded, authorized life story persisted, providing ready cause for countless behaviors--from the boorish and the belligerent to the exemplary and enviable. What we think we know about T has stood in the way of an accurate understanding of its surprising and diverse functions and effects. Rebecca Jordan-Young and Katrina Karkazis focus on what T does in six domains: reproduction, aggression, risk-taking, power, sports, and parenting. At once arresting and deeply informed, Testosterone allows us to see the real T for the first time.-- Provided by publisher
Book
Testosterone Treatment and Fractures in Men with Hypogonadism
In this subtrial involving middle-aged and older men with hypogonadism, testosterone treatment did not result in a lower incidence of clinical fracture than placebo. Fracture incidence was numerically higher with testosterone.
Journal Article
A New Oral Testosterone Undecanoate Formulation Restores Testosterone to Normal Concentrations in Hypogonadal Men
Abstract
Context
A novel formulation of oral testosterone (T) undecanoate (TU) was evaluated in a phase 3 clinical trial.
Objective
Determine efficacy, short-term safety, and alignment of new oral TU formulation with current US approval standards for T replacement therapy.
Design
Randomized, active-controlled, open-label study.
Setting and Patients
Academic and private clinical practice sites; enrolled patients were clinically hypogonadal men 18 to 65 years old.
Methods
Patients were randomized 3:1 to oral TU, as prescribed (JATENZO®; n = 166) or a topical T product once daily (Axiron®; n = 56) for 3 to 4 months. Dose titration was based on average T levels (Cavg) calculated from serial pharmacokinetic (PK) samples. T was assayed by liquid chromatography–mass spectrometry/mass spectrometry. Patients had 2 dose adjustment opportunities prior to final PK visit. Safety was assessed by standard clinical measures, including ambulatory blood pressure (BP).
Results
87% of patients in both groups achieved mean T Cavg in the eugonadal range. Sodium fluoride-ethylenediamine tetra-acetate plasma T Cavg (mean ± standard deviation) for the oral TU group was 403 ± 128 ng/dL (~14 ± 4 nmol/L); serum T equivalent, ~489 ± 155 ng/dL (17 ± 5 nmol/L); and topical T, 391 ± 140 ng/dL (~14 ± 5 nmol/L). Modeling/simulation of T PK data demonstrated that dose titration based on a single blood sample 4 to 6 h after oral TU dose yielded efficacy (93%) equivalent to Cavg-based titration (87%). Safety profiles were similar in both groups, but oral TU was associated with a mean increase in systolic BP of 3 to 5 mm Hg.
Conclusion
A new oral TU formulation effectively restored T to mid-eugonadal levels in hypogonadal patients.
Journal Article
Adverse Events Associated with Testosterone Administration
In a randomized trial, men 65 years of age or older who had low serum testosterone levels and limitations in mobility were assigned to either placebo or testosterone gel to be applied daily for 6 months. The primary end point was improvement in leg-press strength, which was greater with testosterone therapy than with placebo. However, the trial was stopped early because of a greater number of cardiac adverse events in the testosterone group.
In men 65 years of age or older with low serum testosterone levels and limitations in mobility, improvement in leg-press strength was greater with testosterone therapy than with placebo. However, there were more cardiac adverse events in the testosterone group.
Limited mobility is a common geriatric condition that is a predictor of disability, poor quality of life, and death.
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In men, an age-related decline in the serum testosterone concentration is associated with reduced muscle mass and lower-extremity strength, limitations in physical function, and poor mobility.
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Testosterone supplementation increases muscle mass and strength and leg power, all of which are important determinants of mobility.
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Previous trials of testosterone supplementation have been conducted primarily among healthy older men. The safety and efficacy of testosterone treatment in improving muscle performance and physical function in older men with limitations in mobility . . .
Journal Article
Cardiovascular Safety of Testosterone-Replacement Therapy
In a randomized trial involving men with hypogonadism and preexisting or a risk of cardiovascular disease, testosterone therapy was noninferior to placebo with respect to major adverse cardiac events.
Journal Article
Effects of Testosterone Treatment in Older Men
In this study, men 65 years of age or older with low serum testosterone and symptoms of hypoandrogenism received testosterone or placebo for a year. Testosterone had a moderate benefit in sexual function and some benefit in mood but no benefit in vitality or walking distance.
Testosterone concentrations in men decrease with increasing age.
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Many symptoms and conditions similar to those that are caused by low testosterone levels in men with pituitary or testicular disease become more common with increasing age. Such symptoms include decreases in mobility, sexual function, and energy. These parallels suggest that the lower testosterone levels in older men may contribute to these conditions.
Previous trials of testosterone treatment in men 65 years of age or older, however, have yielded equivocal results. Although testosterone treatment consistently increased muscle mass and decreased fat mass,
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effects on physical performance,
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sexual function, . . .
Journal Article
Gonadal Steroids and Body Composition, Strength, and Sexual Function in Men
This study, designed to determine the relative degree of testosterone deficiency, estradiol deficiency, or both at which undesirable bodily changes occur, showed that some features of male hypogonadism are due to both androgen deficiency and estrogen deficiency.
Testosterone therapy is prescribed for millions of men each year, and the number is increasing rapidly. Prescription sales of testosterone increased by 500% in the United States between 1993 and 2000.
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Most testosterone prescriptions are written to treat nonspecific symptoms, such as fatigue or sexual dysfunction, when accompanied by testosterone levels below the laboratory reference range. Currently, testosterone levels that are at least 2 SD below the mean value for healthy young adults are classified as low.
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Although convenient, this classification fails to consider the physiological consequences of specific testosterone levels.
More than 80% of circulating estradiol in men . . .
Journal Article