Prostate size in hypogonadal men treated with a nonscrotal permeation-enhanced testosterone transdermal system

Prostate Risk and Monitoring During Testosterone Replacement Therapy

ABSTRACT

Men with hypogonadism have reduced risk of prostate cancer mortality; whether testosterone treatment increases the risk of prostate safety events in men with hypogonadism remains controversial. Several studies including 4 larger randomized trials-the Testosterone Trials, TEstosterone and Atherosclerosis Progression in Aging Men (TEAAM) trial, Testosterone for Diabetes Mellitus trial, and Testosterone Replacement therapy for Assessment of long-term Vascular Events and efficacy ResponSE in hypogonadal men (TRAVERSE) trial-treated men with testosterone or placebo for 1 year or longer and reported prospectively ascertained prostate safety data. The TRAVERSE Trial, because of its large size, longer duration, and adjudication of prostate events, has provided comprehensive data on the risk of adverse prostate events during testosterone replacement therapy (TRT). Among men with hypogonadism, carefully screened to exclude those at high risk of prostate cancer, the incidences of high-grade or any prostate cancer, acute urinary retention, surgical procedure for benign prostatic hyperplasia, prostate biopsy, or new pharmacologic therapy for lower urinary tract symptoms were low and did not differ between the testosterone and placebo groups. Testosterone did not worsen lower urinary tract symptoms. TRT was associated with a greater increase in prostate-specific antigen than placebo in the first year of treatment.

CONCLUSION

Testosterone treatment of men with hypogonadism, screened to exclude those at high risk of prostate cancer, is associated with low risk of adverse prostate events. Baseline evaluation of prostate cancer risk and a standardized monitoring plan can minimize the risk of unnecessary prostate biopsy while enabling the detection of high-grade prostate cancers in men receiving TRT.

Hypogonadism and urologic surgeries: a narrative review

Background and Objective

Previous studies indicated that the treatment of male hypogonadism can be beneficial for intraoperative and postsurgical outcomes. In this study, we aimed to determine the impact of male hypogonadism on urologic surgeries. We provided an overview of the key studies in the field with the focus on the outcomes of urologic surgeries in hypogonadal men with/without testosterone replacement therapy (TRT).

Methods

We performed a literature review in PubMed and Google Scholar databases for the most relevant articles pertaining to the outlined topics without placing any limitations on publication years or study designs. We included full-text English articles published in peer reviewed journals between January 1970 and March 2022.

Key Content and Findings

Androgen deficiency is a common finding after major urologic surgeries. Although guidelines recommend against TRT in men with prostate carcinoma, recent investigations showed no association between TRT and disease progression and recurrence. Indeed, recent evidence suggested that low androgen levels could be related to high grade prostate carcinoma and increased risk of upgrading from low to high grade disease. Investigations on the application of TRT in benign prostatic hyperplasia (BPH) patients also revealed contrasting results. While some studies suggested higher rates of prostate-related events in men who received TRT, others showed that TRT could alleviate urinary symptoms in hypogonadal men with BPH. Decreased testosterone level is commonly seen in bladder cancer patients. The treatment of perioperative androgen deficiency can reduce postoperative morbidities and lower the risk of recurrence in these patients. Low testosterone levels are observed in approximately half of the men who undergo artificial urinary sphincter (AUS) placement and can increase the risk of complications.

Conclusions

The role of testosterone treatment in patients with urologic diseases such as prostate carcinoma and BPH is controversial. Further investigations are needed to determine the impact of hypogonadism and TRT on the outcomes of urologic surgeries in patients with androgen deficiency.

The effect of testosterone replacement therapy on bladder functions, histology, apoptosis, and Rho-kinase expression in bladder outlet obstruction and hypogonadism rat model

Background/aim

The effect of testosterone replacement therapy was investigated on bladder functions, histology, apoptosis as well as Rho-kinase expression in the rat bladder outlet obstruction (BOO) and hypogonadism models.

Materials and methods

30 mature male rats divided into 4 groups: sham group (n = 8), BOO group (n = 8), BOO + orchiectomy group (n = 7), BOO + orchiectomy + testosterone (T) treatment group (n = 7). Cystometric findings, apoptosis index, Rho-kinase (ROCK-2) expression, and smooth muscle/collagen ratio were compared.

Results

BOO did not change ROCK-2 expression level, compared to sham group (P > 0.05). However, when compared to BOO group (P < 0.01), BOO + orchiectomy led ROCK-2 increase. The testosterone treatment failed to reverse the up-regulation of ROCK-2 induced by orchiectomy although it tended to lower ROCK-2 level. Compared to sham group (P = 0.002), changes in maximal bladder capacity and leak point pressure were higher (P = 0.026, P = 0.001), and bladder compliance was lower in BOO group. Also, the apoptosis index was different between the two groups (P = 0.380). Smooth muscle/collagen ratio was higher in BOO + orchiectomy + T group than in BOO + orchiectomy group (P = 0.010).

Conclusions

The research draws attention to alternating treatment approaches in case of the presence of hypogonadism and BOO.

Advancements in the gold standard: Measuring steroid sex hormones by mass spectrometry

Sex hormones, such as testosterone and estrogens, play an essential role in regulating physiological and reproductive development throughout the lifetime of the individual. Although variation in levels of these hormones are observed throughout the distinct stages in life, significant deviations from reference ranges can result in detrimental effects to the individual. Alterations, by either an increase or decrease, in hormone levels are associated with physiological changes, decreased reproductive capabilities, and increased risk for diseases. Hormone therapies (HTs) and assisted reproductive technologies (ARTs) are commonly used to address these factors. In addition to these treatments, gender-affirming therapies, an iteration of HTs, are also a prominent treatment for transgender individuals. Considering that the effectiveness of these treatments relies on achieving therapeutic hormone levels, monitoring of hormones has served as a way of assessing therapeutic efficay. The need for reliable methods to achieve this task has led to great advancements in methods for evaluating hormone concentrations in biological matrices. Although immunoassays are the more widely used method, mass spectrometry (MS)-based methods have proven to be more sensitive, specific, and reliable. Advances in MS technology and its applications for therapeutic hormone monitoring have been significant, hence integration of these methods in the clinical setting is desired. Here, we provide a general overview of HT and ART, and the immunoassay and MS-based methods currently utilized for monitoring sex hormones. Additionally, we highlight recent advances in MS-based methods and discuss future applications and considerations for MS-based hormone assays.

Safety of testosterone therapy in men with prostate cancer

Introduction: The use of testosterone therapy (TTh) in men with prostate cancer (PCa) is relatively new, and controversial, due to the longstanding maxim that TTh is contraindicated in men with PCa. Scientific advances have prompted a reevaluation of the potential role for TTh in men with PCa, particularly as TTh has been shown to provide important symptomatic and general health benefits to men with testosterone deficiency (TD), including many men with PCa who may expect to live 30-50 years after diagnosis. Areas covered: This review outlines the historical underpinnings of the historical belief that TTh 'fuels' PCa and the experimental and clinical studies that have radically altered this view, including description of the saturation model. The authors review studies of TTh in men with PCa following radical prostatectomy and radiation therapy, in men on active surveillance, and in men with advanced or metastatic PCa. Expert opinion: TTh provides important symptomatic and overall health benefits for men with PCa who have TD. Although more safety studies are needed, TTh is a reasonable therapeutic option for men with low-risk PCa after surgery or radiation. Data in men on active surveillance are limited, but initial reports are reassuring.

Comprehensive evaluation of androgen replacement therapy in aging Japanese men with late-onset hypogonadism

OBJECTIVE

This study assessed the efficacy and safety of testosterone replacement therapy (TRT) in aging Japanese men with late-onset hypogonadism (LOH).

METHODS

This study included 50 (median age: 57.7 years) Japanese men with LOH, who were consecutively enrolled and treated with TRT for at least six months at our institution. We evaluated the following measurements before and after six months of treatment with TRT as follows: blood tests, prostate volume, residual urine volume, self-ratings for International Index of Erectile Function 5 (IIEF-5), International Prostate Symptom Score (IPSS), Self-Rating Depression Scale (SDS), Aging Male Symptom (AMS) and the Medical Outcomes Study 8-item Short-Form health survey (SF-8).

RESULTS

Following six months of TRT, the levels of testosterone, red blood cells, hemoglobin and hematocrit were significantly increased from baseline, while total cholesterol level was significantly decreased from baseline. Furthermore, TRT led to a significant increase in IIEF-5 score and a significant decrease in IPSS score. Of 30 men who were diagnosed with depression at baseline, only 11 men (36.7%) were still suffering from depression after TRT, and SDS scores were significantly decreased from baseline at month six. Treatment with TRT led to a significant decrease in all scores of the AMS scale as well as a significant improvement in all scores of the SF-8 survey, with the exception of the bodily pain score.

CONCLUSION

These findings suggest that TRT is an effective and safe treatment for aging Japanese men with LOH. TRT improved depressive symptoms as well as health-related quality of life.

Prostate volume and growth during testosterone replacement therapy is related to visceral obesity in Klinefelter syndrome

OBJECTIVE

Klinefelter syndrome (KS) is a chromosomal alteration characterized by increased risk of metabolic syndrome, mainly caused by visceral obesity. In the last years, obesity has been studied as a potential risk factor for prostate disease and recently a link has been demonstrated between visceral adiposity with prostate volume. The aim of this study was to analyze the relationship between obesity and prostate volume and growth during testosterone therapy in KS subjects.

DESIGN AND METHODS

We evaluated reproductive hormones, metabolic parameters, anthropometric measures, PSA, and prostate volume in 121 naïve non-mosaic KS patients and 60 age-matched healthy male controls. Fifty-six KS hypogonadic subjects were treated with testosterone-gel 2% and reevaluated after 18 months of treatment.

RESULTS

Prostate volume in KS was positively related to waist circumference (WC). The KS group with WC ≥94 cm had significantly higher prostate volume, BMI, insulin plasma levels, homeostasis model assessment index, total cholesterol, triglycerides, and glycemia with respect to the KS group with WC <94 cm. After testosterone replacement therapy, only hypogonadic KS men with WC ≥94 cm had a statistically significant increase in prostate volume. Furthermore, in untreated KS subjects, prostate volume showed a statistically significant increase after 18 months of follow-up only in subjects with WC ≥94 cm.

CONCLUSIONS

This study showed that visceral obesity, insulin resistance, and lipid and glucose metabolism alterations are associated with prostate volume and growth during testosterone replacement therapy in KS, independently from androgen or estrogen levels. These latter findings might provide the basis for a better management and follow-up of KS subjects.

Hormone replacement therapy in the geriatric patient: current state of the evidence and questions for the future--estrogen, progesterone, testosterone, and thyroid hormone augmentation in geriatric clinical practice: part 2

The data reviewed herein show that hormone replacement therapies improve some conditions associated with aging. Additionally, some of the long-held fears of significant side effects associated with hormone supplementation may be overstated, especially when providing patients with individualized care and optimal monitoring. We encourage clinicians to consider such interventions based on the evidence presented.More long-term studies are needed to further quantify and substantiate the risks and benefits associated with the use of such therapies.

Onset of effects of testosterone treatment and time span until maximum effects are achieved

OBJECTIVE

Testosterone has a spectrum of effects on the male organism. This review attempts to determine, from published studies, the time-course of the effects induced by testosterone replacement therapy from their first manifestation until maximum effects are attained.

DESIGN

Literature data on testosterone replacement.

RESULTS

Effects on sexual interest appear after 3 weeks plateauing at 6 weeks, with no further increments expected beyond. Changes in erections/ejaculations may require up to 6 months. Effects on quality of life manifest within 3-4 weeks, but maximum benefits take longer. Effects on depressive mood become detectable after 3-6 weeks with a maximum after 18-30 weeks. Effects on erythropoiesis are evident at 3 months, peaking at 9-12 months. Prostate-specific antigen and volume rise, marginally, plateauing at 12 months; further increase should be related to aging rather than therapy. Effects on lipids appear after 4 weeks, maximal after 6-12 months. Insulin sensitivity may improve within few days, but effects on glycemic control become evident only after 3-12 months. Changes in fat mass, lean body mass, and muscle strength occur within 12-16 weeks, stabilize at 6-12 months, but can marginally continue over years. Effects on inflammation occur within 3-12 weeks. Effects on bone are detectable already after 6 months while continuing at least for 3 years.

CONCLUSION

The time-course of the spectrum of effects of testosterone shows considerable variation, probably related to pharmacodynamics of the testosterone preparation. Genomic and non-genomic effects, androgen receptor polymorphism and intracellular steroid metabolism further contribute to such diversity.

Prostate size correlates with fasting blood glucose in non-diabetic benign prostatic hyperplasia patients with normal testosterone levels

We evaluated the correlations between BMI, fasting glucose, insulin, testosterone level, insulin resistance, and prostate size in non-diabetic benign prostatic hyperplasia (BPH) patients with normal testosterone levels. Data from 212 non-diabetic BPH patients with normal testosterone levels, who underwent transurethral resection of the prostate (TURP) due to medical treatment failure, were evaluated retrospectively. Patients with prostate specific antigen (PSA) levels of ≥ 3 ng/mL underwent multicore transrectal prostate biopsy before TURP to rule out prostate cancer. Patients with diabetes mellitus (DM) or serum testosterone levels of < 3.50 ng/mL were excluded from analysis. Correlations between clinical and laboratory parameters were determined. Prostate size correlated positively with age (r = 0.227, P < 0.001), PSA (r = 0.510, P < 0.001), and fasting glucose level (r = 0.186, P = 0.007), but not with BMI, testosterone, insulin level, or insulin resistance (each P > 0.05). Testosterone level inversely correlated with BMI (r = -0.327, P < 0.001), insulin level (r = -0.207, P = 0.003), and insulin resistance (r = -0.221, P = 0.001), but not with age, prostate size, PSA, or fasting glucose level (each P > 0.05). Upon multiple adjusted linear regression analysis, prostate size correlated with elevated PSA (P < 0.001) and increased fasting glucose levels (P = 0.023). In non-DM BPH patients with normal testosterone levels, fasting glucose level is an independent risk factor for prostate hyperplasia.

Changes in prostate specific antigen in hypogonadal men after 12 months of testosterone replacement therapy: support for the prostate saturation theory

PURPOSE

We measured prostate specific antigen after 12 months of testosterone replacement therapy in hypogonadal men.

MATERIALS AND METHODS

Data were collected from the TRiUS (Testim® Registry in the United States), an observational registry of hypogonadal men on testosterone replacement therapy (849). Participants were Testim naïve, had no prostate cancer and received 5 to 10 gm Testim 1% (testosterone gel) daily.

RESULTS

A total of 451 patients with prostate specific antigen and total testosterone values were divided into group A (197 with total testosterone less than 250 ng/dl) and group B (254 with total testosterone 250 ng/dl or greater). The groups differed significantly in free testosterone and sex hormone-binding globulin, but not in age or prostate specific antigen. In group A but not group B prostate specific antigen correlated significantly with total testosterone (r=0.20, p=0.005), free testosterone (r=0.22, p=0.03) and sex hormone-binding globulin (r=0.59, p=0.002) at baseline. After 12 months of testosterone replacement therapy, increase in total testosterone (mean±SD) was statistically significant in group A (+326±295 ng/dl, p<0.001; final total testosterone 516±28 ng/dl) and group B (+154±217 ng/dl, p<0.001; final total testosterone 513±20 ng/dl). After 12 months of testosterone replacement therapy, increase in prostate specific antigen was statistically significant in group A (+0.19±0.61 ng/ml, p=0.02; final prostate specific antigen 1.26±0.96 ng/ml) but not in group B (+0.28±1.18 ng/ml, p=0.06; final prostate specific antigen 1.55±1.72 ng/ml). The average percent prostate specific antigen increase from baseline was higher in group A (21.9%) than in group B (14.1%). Overall the greatest prostate specific antigen was observed after 1 month of treatment and decreased thereafter.

CONCLUSIONS

Patients with baseline total testosterone less than 250 ng/dl were more likely to have an increased prostate specific antigen after testosterone replacement therapy than those with baseline total testosterone 250 ng/dl or greater, supporting the prostate saturation hypothesis. Clinicians should be aware that severely hypogonadal patients may experience increased prostate specific antigen after testosterone replacement therapy.

Treatment of 161 men with symptomatic late onset hypogonadism with long-acting parenteral testosterone undecanoate: effects on body composition, lipids, and psychosexual complaints

INTRODUCTION

Elderly men may suffer from late-onset hypogonadism (LOH). The long-term effects of long-acting testosterone undecanoate (TU) in a large number of LOH men have not yet been reported. Aims.  We analyzed the effects of normalization of plasma testosterone (T) in LOH men.

METHODS

The records of 161 men with LOH (baseline T<300 ng/dL) were reviewed and 100 men had used parenteral TU for >12 months. The mean duration of treatment was 90.6 weeks (54 to 150 weeks).

MAIN OUTCOME MEASURES

Body mass index (BMI), waist circumference, percentage body fat, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, prostate-specific antigen (PSA), and hematocrit were measured. Further the Aging Male Symptoms' scale (AMS) and the International Index of Erectile Function (IIEF-5 and 15) were scored.

RESULTS

T therapy was associated with a significant decline in waist circumference (P=0.028) and percentage body fat (P<0.001), but no change of BMI. Total cholesterol and LDL cholesterol declined significantly (P=0.005 and P=0.024, respectively), with no significant changes of HDL cholesterol and triglycerides. The scores of sub-scales of AMS (psychological, somotovegetative and sexual factors) decreased (P=0.044, P=0.200 and P=0.071, respectively). The mean IIEF-5 (P=0.011) and IIEF-15 scores (P=0.021) improved significantly. Erectile function domain, orgasmic function domain, sexual desire domain, intercourse satisfaction domain, and overall satisfaction domain improved. Median PSA rose from 0.95 (0.640; 1.558) ng/mL to 1.480 (1.015; 2.275) ng/mL (P<0.001), with 11 patients >4 ng/mL (4.01-13.21). On biopsy there was no evidence for malignancy. The mean hematocrit level increased significantly from 42.3±3.4% to 47.1±3.8%.

CONCLUSIONS

Normalizing serum T in men with LOH resulted in improvement of the metabolic syndrome, mood and sexual functions and appeared acceptably safe.

Comparison of oral versus transdermal testosterone supplementation in hypogonadal men

: To compare mean serum total testosterone, bioavailable-testosterone, and dihydrotestosterone levels between transdermal testosterone and oral testosterone undecanoate treatment.

: Multicentre, randomized, cross-over study; 44 men >18 years, testosterone ≤2.5 ng/mL. Two patches (Testopatch

: Mean age 49 years. Mean testosterone before inclusion 1.99 ng/mL. Mean testosterone serum levels over the last 48 h of Testopatch treatment were superior to Pantestone (4.64 vs. 2.58 ng/mL, p<0.001). Testosterone trough levels at the end of each treatment period were significantly higher for Testopatch (3.15 vs. 2.45 ng/mL, p<0.01). Bioavailable-testosterone levels over the first and last 48 h of treatment were significantly greater with Testopatch than with Pantestone (p=0.001 and p<0.01). Dihydrotestosterone levels over the first and last 48 h of treatment (0.71 vs. 1.05 ng/mL and 0.68 vs. 0.89 ng/mL) as well as at trough (0.59 vs. 0.96 ng/mL) were significantly lower with Testopatch than with Pantestone (p<0.001, p<0.05, and p<0.001). SHBG levels decreased by Pantestone but not by Testopatch (p<0.001).

: Testopatch was superior to Pantestone to increase testosterone and bioavailable-testosterone levels in hypogonadal men from the first days and throughout the three weeks of treatment. Pantestone increased dihydrotestosterone to a larger extent and decreased SHBG.

Safety and efficacy of testosterone gel in the treatment of male hypogonadism

Transdermal testosterone gels were first introduced in the US in 2000. Since then, they have emerged as a favorable mode of testosterone substitution. Serum testosterone levels reach a steady-state in the first 24 hours of application and remain in the normal range for the duration of the application. This pharmacokinetic profile is comparable to that of testosterone patch but superior to injectable testosterone esters that are associated with peaks and troughs with each dose. Testosterone gels are as efficacious as patches and injectable forms in their effects on sexual function and mood. Anticipated increases in prostate-specific antigen with testosterone therapy are not significantly different with testosterone gels, and the risk of polycythemia is lower than injectable modalities. Application site reactions, a major drawback of testosterone patches, occur less frequently with testosterone gels. However, inter-personal transfer is a concern if appropriate precautions are not taken. Superior tolerability and dose flexibility make testosterone gel highly desirable over other modalities of testosterone replacement. Androgel and Testim, the two currently available testosterone gel products in the US, have certain brand-specific properties that clinicians may consider prior to prescribing.

Position stand on androgen and human growth hormone use

Hoffman, JR, Kraemer, WJ, Bhasin, S, Storer, T, Ratamess, NA, Haff, GG, Willoughby, DS, and Rogol, AD. Position stand on Androgen and human growth hormone use. J Strength Cond Res 23(5): S1-S59, 2009-Perceived yet often misunderstood demands of a sport, overt benefits of anabolic drugs, and the inability to be offered any effective alternatives has fueled anabolic drug abuse despite any consequences. Motivational interactions with many situational demands including the desire for improved body image, sport performance, physical function, and body size influence and fuel such negative decisions. Positive countermeasures to deter the abuse of anabolic drugs are complex and yet unclear. Furthermore, anabolic drugs work and the optimized training and nutritional programs needed to cut into the magnitude of improvement mediated by drug abuse require more work, dedication, and preparation on the part of both athletes and coaches alike. Few shortcuts are available to the athlete who desires to train naturally. Historically, the NSCA has placed an emphasis on education to help athletes, coaches, and strength and conditioning professionals become more knowledgeable, highly skilled, and technically trained in their approach to exercise program design and implementation. Optimizing nutritional strategies are a vital interface to help cope with exercise and sport demands (). In addition, research-based supplements will also have to be acknowledged as a strategic set of tools (e.g., protein supplements before and after resistance exercise workout) that can be used in conjunction with optimized nutrition to allow more effective adaptation and recovery from exercise. Resistance exercise is the most effective anabolic form of exercise, and over the past 20 years, the research base for resistance exercise has just started to develop to a significant volume of work to help in the decision-making process in program design (). The interface with nutritional strategies has been less studied, yet may yield even greater benefits to the individual athlete in their attempt to train naturally. Nevertheless, these are the 2 domains that require the most attention when trying to optimize the physical adaptations to exercise training without drug use.Recent surveys indicate that the prevalence of androgen use among adolescents has decreased over the past 10-15 years (). The decrease in androgen use among these students may be attributed to several factors related to education and viable alternatives (i.e., sport supplements) to substitute for illegal drug use. Although success has been achieved in using peer pressure to educate high school athletes on behaviors designed to reduce the intent to use androgens (), it has not had the far-reaching effect desired. It would appear that using the people who have the greatest influence on adolescents (coaches and teachers) be the primary focus of the educational program. It becomes imperative that coaches provide realistic training goals for their athletes and understand the difference between normal physiological adaptation to training or that is pharmaceutically enhanced. Only through a stringent coaching certification program will academic institutions be ensured that coaches that they hire will have the minimal knowledge to provide support to their athletes in helping them make the correct choices regarding sport supplements and performance-enhancing drugs.The NSCA rejects the use of androgens and hGH or any performance-enhancing drugs on the basis of ethics, the ideals of fair play in competition, and concerns for the athlete's health. The NSCA has based this position stand on a critical analysis of the scientific literature evaluating the effects of androgens and human growth hormone on human physiology and performance. The use of anabolic drugs to enhance athletic performance has become a major concern for professional sport organizations, sport governing bodies, and the federal government. It is the belief of the NSCA that through education and research we can mitigate the abuse of androgens and hGH by athletes. Due to the diversity of testosterone-related drugs and molecules, the term androgens is believed to be a more appropriate term for anabolic steroids.

ISA, ISSAM, EAU, EAA and ASA recommendations: investigation, treatment and monitoring of late-onset hypogonadism in males

The new ISA, ISSAM, EAU, EAA and ASA recommendations on the investigation, treatment and monitoring of late-onset hypogonadism in males provide updated evidence-based information for clinicians who diagnose and treat patients with adult onset, age related testosterone deficiency.

Testosterone therapy in hypogonadal men and potential prostate cancer risk: a systematic review

This paper provides a systematic review of the literature about prostate cancer risk associated with testosterone therapy for hypogonadism. A comprehensive search of MEDLINE, EMBASE and other resources was conducted to identify articles that highlight occurrences of prostate cancer in men receiving testosterone therapy for hypogonadism treatment. Articles that met study inclusion criteria were assessed for causality between testosterone treatment and prostate cancer, increased prostate-specific antigen or abnormal digital rectal examination findings. Of 197 articles relating to testosterone therapy, 44 met inclusion criteria: 11 placebo-controlled, randomized studies; 29 non-placebo-controlled studies of men with no prostate cancer history; and 4 studies of hypogonadal men with history of prostate cancer. Of studies that met inclusion criteria, none demonstrated that testosterone therapy for hypogonadism increased prostate cancer risk or increased Gleason grade of cancer detected in treated vs untreated men. Testosterone therapy did not have a consistent effect on prostate-specific antigen levels.

The effect of testosterone therapy on lower urinary tract symptoms/bladder and sexual functions in men with symptomatic late-onset hypogonadism

OBJECTIVE

To prospectively investigate the effect of testosterone therapy on lower urinary tract symptoms (LUTS)/bladder and sexual functions in men with symptomatic late-onset hypogonadism (SLOH).

METHODS

The study included 25 men (age range 38 to 73 years) presented with sexual dysfunction, having SLOH, at a single university hospital. All men received testosterone replacement therapy with transdermal testosterone 50-100 mg gel per day for one year. Urodynamic studies with pressure-flow analysis, measurement of prostate volume, prostate specific antigen (PSA) and free PSA level, International Prostate Symptom Score (IPSS), Aging Male Symptom (AMS) scale and International Index of Erectile Function (IIEF-5) score were recorded in all men before and after one year of the treatment.

RESULTS

The mean AMS score significantly decreased from 40.4 +/- 7.3 to 28.8 +/- 5.31 (p = 0.001), and mean IIEF-5 score significantly increased from 8.84 +/- 3.76 to 14.36 +/- 3.62 (p = 0.001). The mean maximal bladder capacity and compliance significantly increased (p = 0.007 and p = 0.032, respectively), and mean detrusor pressure at Qmax significantly decreased from pre-treatment to post-treatment (p = 0.017).

CONCLUSION

This study suggests that in addition to improvement in sexual functions, testosterone therapy may also improve LUTS/bladder functions by increasing bladder capacity and compliance and decreasing detrusor pressure at maximal flow in men with SLOH.

State of the Art Reviews: Male Menopause: Fact or Fiction?

The possible existence of a menopause-like process in aging men has been speculated, given certain age-related hormonal and other biological changes noted to occur. Specifically, a slow decline in serum testosterone levels has been reported to occur with normal male aging. Androgen deficiency, which may result from this process, could have an effect on various systems and physiologic parameters, including bone density, body composition, sexual function, and the cardiovascular system, thus significantly affecting health and quality-of-life issues in older men. There has been an increasing interest in evaluating the possible use of testosterone replacement in preventing some detrimental aspects of aging and age-related hypogonadism, as well as in the investigation of the potential adverse effects of this therapy on different target organs. It is the purpose of this review to summarize currently available information with regard to the changes in testosterone and other hormones in older men, discuss their possible clinical manifestations and relationship with other age-related changes, and provide an updated description of testosterone replacement therapy for older men, including its indications, formulations, and safety considerations.

Drug insight: testosterone preparations

Testosterone has been used for substitution therapy in testicular and hypothalamopituitary diseases for almost six decades, with injectable testosterone esters and implanted testosterone pellets being the mainstay of treatment. Growing interest in the possible use of testosterone in nonclassical situations such as male contraception, aging (late-onset hypogonadism), muscle-wasting conditions like HIV, erectile dysfunction, and female hypoactive sexual disorder has stimulated research, leading to the development of several new modes of administration of testosterone. Transdermal patches, gels, mucoadhesive sustained-release buccal tablets and long-acting testosterone esters are designed to provide testosterone levels that approximate normal physiologic levels, to improve patient acceptability, and to further increase the number of treatment options available. In this Review, we briefly describe the chemistry, mechanism of action, and metabolism of testosterone. We then discuss the pharmacokinetics, advantages, and disadvantages of various formulations and summarize the various preparations currently available.

Management of the cardinal features of andropause

There are several problems facing aging men, especially sexual dysfunction, hypogonadism, and psychologic changes. This constellation of changes is sometimes referred to as "manopause" or "andropause." Unlike the dramatic changes in the hormonal milieu occurring during menopause in women, the age-related changes in reproductive hormones of men are subtle and occur gradually throughout the years of mature life. It has been estimated that circulating testosterone (T) declines longitudinally from age 19 at an average rate of 1% per year. The free or dialyzable fraction of serum T and the bioavailable (the sum of free fraction and loosely bound to albumin fraction) T decline more rapidly with age. Although the essential role of androgens in reproductive tissue development and emergence of secondary sex characteristics is well known, their role in adult sexual function seems to be primarily facultative. The effect of T on the central nervous system extends beyond sexual behavior. T has been shown to alter mood, memory, ability to concentrate, and the overall sense of vigor and well being that may interact with a host of other psychologic changes associated with aging. Disordered erectile function is not generally an endocrine problem but rather vascular, neurologic, and psychogenic in origin. It also may be the first sign of systemic vascular disease. The clinical management of andropause requires an individualized approach. In some men, the main problem may be psychologic, whereas in others, hypogonadism may play an important role. Many with erectile failure, suffer silently regardless of its etiology. In this review, we suggest some practical guidelines for the management of these conditions.

The current status of therapy for symptomatic late-onset hypogonadism with transdermal testosterone gel

For over 50 years, testosterone therapy has been used for the treatment of hypogonadism. In recent years, there has been an increase in the use of testosterone therapy for men with late-onset hypogonadism, as more convenient and effective modes of application are developed. Testosterone therapy in these men can significantly improve their sense of well-being, and lead to increases in muscle and bone mass, upper body strength, virility and libido [Gruenewald, Matsumoto. J Am Geriatr Soc 2003;51:101; Morales. Aging Male 2004; in press]. However, ensuring that optimal testosterone therapy is achieved in men with hypogonadism remains challenging. Oral delivery of unmodified testosterone is not possible, due to rapid first-pass metabolism and its short half-life. Therefore, different derivatives and formulations of testosterone have been developed to enhance potency, prolong duration of action or improve bioavailability. In addition, several different routes of administration have now been evaluated, including intramuscular injections, oral formulations, transdermal patches, transbuccal systems and transdermal testosterone gel. Despite the broad range of testosterone therapy on offer, each form has its benefits and limitations, and some will suit one patient more than another. An important concern among clinicians is that testosterone therapy may cause or promote prostate cancer. While current evidence supports the safety of testosterone therapy, androgens are growth factors for pre-existing prostate cancer. Therefore, before therapy is initiated, careful digital rectal examination and determination of prostate-specific antigen (PSA) in serum should be performed, in order to exclude evident or suspected prostate cancer. The first 3-6 months after initiating testosterone therapy is the most critical time for monitoring effects on the prostate. Therefore, it is important to monitor PSA levels every 3 months for the first year of treatment; thereafter, regular monitoring (mostly for prostate safety but also for cardiovascular and haematological safety) during therapy is mandatory.

The therapeutic potential of testosterone patches

In the last decade, transdermal delivery of testosterone (T) has been shown to be a safe and effective means of treating male hypogonadism. Transdermal T patches can provide for physiologic androgen replacement in over 90% of men with hypogonadism. In addition, T patches have been shown to be equivalent to im. T esters in restoring normal male libido,sexual function and bone mineral density without harmful side-effects.Furthermore, in sharp contrast to periodic im. injections of T, transdermal T patches, when used daily, restore the normal circadian rhythm of T levels. The physiological and clinical importance of these circadian patterns,however, is presently unknown. The first transdermal patch to be marketed is applied to shaved scrotal skin. Newer patches can be applied to non-scrotal skin; however, these patches are associated with a significant rate of skin reactions that may require discontinuation. The main drawback to transdermal T delivery is cost, ten to twenty times the monthly cost of im. T, the method currently used to treat most hypogonadal men.Nevertheless, transdermal T patches constitute a major advance in the therapy of male hypogonadism as they allow for safe, non-invasive administration of T.

Drug delivery across the skin

Since the introduction of the first through the skin (TTS) therapeutic in 1980, a total of 34 TTS products have been marketed and numerous drugs have been tested by more than 50 commercial organisations for their suitability for TTS delivery. Most of the agents which have been tested have had low molecular weights, due to the impermeability of the skin barrier. This barrier resides in the outermost skin layer, the stratum corneum. It is mechanical, anatomical, as well as chemical in nature; laterally overlapping cell multi-layers are sealed by tightly packed, intercellular, lipid multi-lamellae. Chemical skin permeation enhancers increase the transport across the barrier by partly solubilising or extracting the skin lipids and by creating hydrophobic pores. This is often irritating and not always well-tolerated. The TTS approach allows drugs (< 400 kDa in size) to permeate through the resulting pores in the skin, with a short lag-time and subsequent steady-state period. Drug bioavailability for TTS delivery is typically below 50%, avoiding the first pass effect. Wider, hydrophilic channels can be generated by skin poration, with the aid of a small electrical current (> 0.4 mA/cm2) across the skin (iontophoresis) or therapeutic ultrasound (few W/cm2; sonoporation). High-voltage (> 150 V, electroporation) widens the pores even more and often irreversibly. These standard poration methods require experience and equipment and are therefore, not practical; at best, charged/small molecules (< or = 4000 kDa in size) can be delivered efficiently across the skin. In spite of the potential harm of gadget-driven skin poration, this method is used to deliver molecules which conventional TTS patches are unable to deliver, especially polypeptides. Lipid-based drug carriers (liposomes, niosomes, nanoparticle microemulsions, etc.) were proposed as alternative, low-risk delivery vehicles. Such suspensions provide an improved drug reservoir on the skin, but the aggregates remain confined to the surface. Conventional carrier suspensions increase skin hydration and/or behave as skin permeation enhancers. The recently developed carriers; Transferomes, comprise pharmaceutically-acceptable, established compounds and are thought to penetrate the skin barrier along the naturally occurring transcutaneous moisture gradient. Transfersomes are believed to penetrate the hydrophilic (virtual) channels in the skin and widen the former after non-occlusive administration. Both small and large hydrophobic and hydrophilic molecules are deliverable across the stratum after conjugation with Transfersomes. Drug distribution after transdermal delivery probably proceeds via the lymph. This results in quasi-zero order kinetics with significant systemic drug levels reached after a lag-time of up to a few hours. The relative efficiency of TTS drug delivery with Transfersomes is typically above 50 %; with the added possibility of regional drug targeting.

Androgen replacement in the treatment of Klinefelter's syndrome: efficacy and safety of a nonscrotal permeation-enhanced testosterone transdermal system

OBJECTIVE

To report the efficacy and safety of a permeation-enhanced nonscrotal testosterone transdermal (TTD) system for the treatment of Klinefelter's syndrome.

METHODS

Fifteen male patients with Klinefelter's syndrome, including 12 patients who received previous intramuscular (IM) treatment with testosterone esters, were part of the study population from three phase III clinical studies; 13 completed the studies. Patients applied two TTD systems nightly for 6 months or more. Nocturnal erections were assessed by RigiScan monitoring; sexual function was evaluated by using the Watts and Davidson questionnaires. Hypogonadal symptoms were determined by direct patient questioning.

RESULTS

Mean morning serum testosterone levels increased to within normal range in all 13 patients (from 5.9 +/- 3.2 nmol/L at hypogonadal baseline to 22.3 +/- 5.6 nmol/L at 6 months). Luteinizing hormone levels decreased to within normal range in six patients and showed clinically significant decreases in four of the other seven patients (from 25 +/- 12 IU/L at hypogonadal baseline to 17 +/- 11 IU/L at 6 months). Nocturnal erections improved significantly during TTD system therapy in comparison with the hypogonadal state. Patient self-reported measures of sexual functioning were comparable to those during prior IM testosterone treatment and better than during the hypogonadal state. Hypogonadal symptoms decreased during TTD therapy in comparison with hypogonadal baseline. No clinically significant changes were noted in prostate volume, prostate-specific antigen, or lipid values. Three patients experienced anxiety or depression during TTD treatment, requiring discontinuation of therapy in one case and use of antidepressants in the other two.

CONCLUSION

The testosterone patches were generally well tolerated in all patients. The nonscrotal TTD system for testosterone replacement is a safe and effective treatment for patients with Klinefelter's syndrome.

Testosterone treatment for the aging man: the controversy

The issues surrounding androgen replacement therapy in men with symptomatic late-onset hypogonadism has been marred in controversy even before the identification and synthesis of testosterone. The controversy has attained renewed importance because of the ever increasing aging population. Physicians attuned with the various diagnostic approaches, familiar with the advantages and drawbacks of testosterone preparations, and aware of the potential safety issues are well positioned to deal with the hypogonadal man at or beyond middle age. The urologist is in a unique position to assist patients and colleagues in other specialties, particularly in relation to prostate safety. This update focuses on the most prominent areas of controversy.

Clinical experiences with testosterone therapy: prostate safety

Due to a decrease in Leydig cell function, a considerable proportion of men over 50 years of age will develop hypogonadism. Consequently, loss of libido and several other testosterone-dependent symptoms may become evident. When decreased levels of biologically available testosterone are found, and corresponding symptoms are present, these men could be eligible for testosterone substitution therapy. Testosterone treatment in testosterone-deprived men has been shown to improve general well-being, osteoporosis, muscle atrophy, libido and--if present--anemia. Despite these positive effects, testosterone treatment has to be performed with caution. Although it has not been proven that elevation of the serum testosterone level to the normal range results in a greater risk of developing prostate cancer, the effects of testosterone on a prostate cancer already present are well established. Several studies have demonstrated that testosterone treatment does not result in a significant increase in serum levels of prostate-specific antigen (PSA) or prostate volume. The long-term effects, however, are currently unknown. For these reasons, testosterone treatment should be performed only when the presence of prostate cancer is unlikely; i.e. when PSA levels are within normal limits and digital rectal examination does not reveal any suspicious findings. These examinations may still miss some small prostate cancers that could be promoted by testosterone treatment. The determination of PSA levels under testosterone treatment is necessary every 3 months, at least for the first year. Steadily rising PSA levels require immediate cessation of testosterone administration and the initiation of further diagnostic procedures (prostate biopsy), to rule out prostate cancer.

Review article Testosterone therapy in the ageing male: what about the prostate?

The concerns about testosterone therapy in ageing men with late-onset hypogonadism mainly address the risk of prostatic disease, i.e. either benign prostatic hyperplasia (BPH) or prostate cancer (PCa). Both conditions are highly dependent on androgen action and recent clinical data on the cancer-preventive effect of the 5alpha-reductase inhibitor finasteride have supported the possible role of androgens in PCa. However, the clinical data especially on the long-term effects of exogenous androgen substitution in regard to prostate safety are nonconclusive in many respects. As sufficient clinical studies on these risks will not be available in the near future, the approach of testosterone therapy towards prostate complications should be kept on a safe but practical basis. This review includes some recommendations in regard to testosterone therapy and prostate monitoring in patients with BPH and bladder outlet obstruction, with previous history of curative treatment for PCa or with prostatic intraepithelial neoplasia.

Testosterone metabolism and replacement therapy in patients with end-stage renal disease

Hypogonadism is common among men with end-stage renal disease (ESRD), beginning before the need for dialysis and not improved with the initiation of dialysis. Many of the manifestations of hypogonadism, such as bone disease and muscle wasting, are also frequently seen among dialysis patients. There have been few studies of testosterone replacement therapy in this patient population, but available data suggest that testosterone can be administered without adjustment of the doses used in hypogonadal men with normal renal function. Extrapolation from results of treatment of hypogonadal older men with normal renal function suggests that testosterone replacement could improve libido and could have salutary effects on muscle mass and bone mineral density in patients with kidney disease. However, caution is warranted because of the potential side effects of testosterone therapy, and further research is needed to more precisely define the balance of risk and benefit in patients with chronic kidney disease. Specifically it will be important to determine the prevalence and clinical significance of hypogonadism in ESRD patients in the modern era and to measure the effects of replacement therapy on various symptoms of hypogonadism as well as on overall quality of life, physical functioning, and survival.

Male hypogonadism in the primary care clinic

Hypogonadism is common in clinical practice but is frequently unrecognized and underdiagnosed. The common causes of male hypogonadism vary with the age of presentation. The overall prevalence of male hypogonadism based upon low serum total testosterone levels is high and increases with age. There are many pitfalls in making the diagnosis of male hypogonadism. First, male hypogonadism is sometimes difficult to recognize because the signs and symptoms are often nonspecific and overlap with other common syndromes. Second, the biochemical diagnosis of male hypogonadism is not straightforward because it might not be clear which testosterone assay to select from the many that are available. Finally, even after the diagnosis of male hypogonadism is made, the patient and clinician must weigh the potential benefits and risks of androgen replacement therapy. However, new diagnostic tools and therapies are making decisions easier.

Transdermal testosterone gel: pharmacokinetics, efficacy of dosing and application site in hypogonadal men

OBJECTIVE

To determine the regimen that would most effectively maintain serum testosterone concentrations in treated hypogonadal men within the normal reference range of 3-11.4 microg/L.

PATIENTS AND METHODS

Eighteen men aged 24-69 years with either primary or secondary hypogonadism participated in and 16 completed a randomized, six-treatment regimen, three-period (phase), three-way matrix-type crossover study. A 1% and 2% testosterone gel (CP601, Cellegy Pharmaceuticals, Inc., San Francisco, USA) was administered either once or twice daily transdermally at different body sites to determine optimal dosing, application sites, and its pharmacokinetics and tolerability in hypogonadal men. Treatments A-F included 1 g of 1% and 2% gel that was equivalent to 10 or 20 mg of testosterone, applied once or twice daily to the skin of either the thigh or the upper arm. Six men also participated in a study of 3 g of 2% gel that was equivalent to 60 mg of testosterone applied once daily, half on each thigh. Pharmacokinetic variables were calculated for testosterone for each man in each treatment period and the results analysed by anova.

RESULTS

In general the higher dose regimens produced higher serum concentrations of testosterone; the 3 g/2% dose was most successful in maintaining serum testosterone within the normal reference range. The average testosterone concentration (C(avg)) was 6.52 microg/L and all men had a C(avg) of > 3.0 microg/L. The prediction of all men achieving a C(avg) of > 3.0 microg/L was 96%. The mean minimum concentration (C(min)) was 3.83 microg/L and half the patients had a C(min) of > 3.0 microg/L. Most men had serum testosterone levels within the normal reference range throughout the 24 h, and the treatment was well tolerated.

CONCLUSIONS

The 3 g/2% dose applied to the skin daily resulted in serum testosterone in the normal reference range in most hypogonadal men. Dose adjustments to either a lower or higher dose should shift serum testosterone concentration to the desired range in those who do not achieve this range with this dose.

Testosterone replacement therapy in male hypogonadism

In human males 6-7 mg of testosterone are secreted by the testes in a circadian rhythm with a nocturnal rise in testosterone followed by a decline during the day. Testosterone is necessary to induce and maintain secondary sexual characteristics, lean muscle mass, bone density and for normal sexual behaviour and cognitive function in men. Replacement therapy has been shown to be beneficial in men with overt hypogonadism. Natural testosterone should be used and not modified molecules. Testosterone is currently available in oral, intramuscular, subcutaneous and transdermal preparations. Recent advances in testosterone replacement therapy include testosterone gels which provide flexibility in dosing and minimal skin irritation resulting in good compliance, and the development of longer acting intramuscular preparations which result in more stable testosterone levels with longer injection intervals. All patients receiving testosterone should be carefully monitored for changes in hematocrit, liver function, lipid parameters and prostate specific antigen (PSA).This article reviews the current experience with the use of various forms of testosterone for the treatment of male hypogonadism.

Androgen administration in middle-aged and ageing men: effects of oral testosterone undecanoate on dihydrotestosterone, oestradiol and prostate volume

The gradual reduction of plasma testosterone in middle-aged and older men from mid-life onwards coincides paradoxically with the time when there is progressive growth of the prostate, a highly androgen-dependent organ. The growing interest in androgen therapy for older men makes it essential to understand the effects of exogenous testosterone on the non-diseased prostate, yet few studies are available. The present study examined prostate volume, prostate-specific antigen (PSA) and lower urinary tract symptom (IPSS) score in 207 men, aged 40-83 years, presenting with clinical features of age-related androgen deficiency [sexual and/or urinary dysfunction, elevated lutenizing hormone (LH)] who were treated for 6 months with oral testosterone undecanoate (TU). Men were divided into two groups, group 1 (n=92, plasma testosterone levels > 13 nmol/L) were treated with 80 mg daily; group 2 (n=115, plasma testosterone levels < 13 nmol/L) were treated with given 120 mg daily. Before treatment and after 1, 3 and 6 months of treatment, prostate volume was measured by ultrasound and hormones [testosterone, dihydrotestosterone, oestradiol, LH, follicle-stimulating hormone (FSH)] and PSA were measured. Within 1 month of treatment, the elevated blood LH levels were markedly decreased in all men in group 1, as well as most men in group 2. Group 2 was subdivided into men whose LH levels were suppressed (n=95, group 2a) and those whose LH levels did not suppress (n=20, group 2b). Men in group 1 and 2a had marked decreases in prostate volume, PSA and lower urinary tract symptom (IPSS) scores whereas no significant changes were observed in group 2b. Groups 1 and 2a also had more striking suppression of LH, FSH, dihydrotestosterone and oestradiol whereas group 2b had no significant increases in blood testosterone concentrations. These findings suggest that exogenous testosterone in middle-aged and older men with some clinical features of age-related androgen deficiency can retard or reverse prostate growth and that elevated plasma LH may be a useful index of severity of age-related androgen deficiency.

Androgen replacement therapy and prostate safety

Progress in the understanding of the action of exogenous testosterone has diminished many of the concerns that existed regarding its safety. The major interest is now focused on the effects of androgen supplementation on the prostate gland. Many such concerns have been addressed but others remain to be fully elucidated. It is well established that hypogonadal men receiving adequate androgen therapy develop a prostate with a volume similar to what would be expected from their eugonadal counterparts. Androgen therapy results in modest elevations in the PSA and minor changes in flow parameters. Prostate cancer, on the other hand, remains the most prominent of the safety concerns. Although there is no evidence that normal levels of testosterone promote the development of cancer of the prostate, it is clear that the administration of testosterone enhances a pre-existing prostatic malignancy. Androgen supplementation studies have been, in most cases, of short duration and lacked a control cohort. The current evidence does not support the view that appropriate treatment of hypogonadal elderly men with androgens has a causal relationship with prostate cancer. Larger experience, however, is needed. The same criteria applies to the use of other hormones such as dehydrotestosterone, dehydroepiandrosterone follicle stimulating and growth hormone. A set of recommendations regarding androgen replacement therapy and prostate safety is proposed.

Androgen deficiency and the aging male: new urologic perspectives

Among the most prominent health care issues of the 21st century are those relating to aging. Indeed, the elderly represent the fastest growing segment of our population. Typically, a urology practice includes a significant number of elderly males, providing the physician with both a challenge and an opportunity. Androgen deficiency in the aging male, with its detrimental effects on bone, muscle and body composition, sexual function, and psychological well-being, is an area of increasing interest in both the lay press and the medical community. The urologist must understand the pathophysiology of androgen deficiency in the male, recognize and investigate the subtle signs and symptoms of hypogonadism, determine the appropriateness of treatment, and offer informed options to the patient. Health care professionals have a responsibility to make "healthy" aging a priority.

Androgen deficiency in the aging male: pathophysiology, diagnosis, and treatment alternatives

Androgen deficiency in the aging male is associated with negative effects on mood and cognition, diminished sexual function, and osteoporosis. The aging of our population, combined with an increased acceptance of medical technology, has focused greater attention on optimizing health during the "golden years." Androgen replacement therapy may remedy many of the deleterious consequences of hypogonadism. This communication reviews the clinical manifestations and diagnosis of androgen deficiency, the inherent risks and benefits of androgen replacement, and the options of testosterone replacement currently available.

Testosterone dose-response relationships in healthy young men

Testosterone increases muscle mass and strength and regulates other physiological processes, but we do not know whether testosterone effects are dose dependent and whether dose requirements for maintaining various androgen-dependent processes are similar. To determine the effects of graded doses of testosterone on body composition, muscle size, strength, power, sexual and cognitive functions, prostate-specific antigen (PSA), plasma lipids, hemoglobin, and insulin-like growth factor I (IGF-I) levels, 61 eugonadal men, 18-35 yr, were randomized to one of five groups to receive monthly injections of a long-acting gonadotropin-releasing hormone (GnRH) agonist, to suppress endogenous testosterone secretion, and weekly injections of 25, 50, 125, 300, or 600 mg of testosterone enanthate for 20 wk. Energy and protein intakes were standardized. The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively. Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly (change +3.4, 5.2, and 7.9 kg, respectively). The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log testosterone concentrations (r = 0.73, P = 0.0001). Changes in leg press strength, leg power, thigh and quadriceps muscle volumes, hemoglobin, and IGF-I were positively correlated with testosterone concentrations, whereas changes in fat mass and plasma high-density lipoprotein (HDL) cholesterol were negatively correlated. Sexual function, visual-spatial cognition and mood, and PSA levels did not change significantly at any dose. We conclude that changes in circulating testosterone concentrations, induced by GnRH agonist and testosterone administration, are associated with testosterone dose- and concentration-dependent changes in fat-free mass, muscle size, strength and power, fat mass, hemoglobin, HDL cholesterol, and IGF-I levels, in conformity with a single linear dose-response relationship. However, different androgen-dependent processes have different testosterone dose-response relationships.