ORIGINAL RESEARCH—ENDOCRINOLOGY: Wide Variability in Laboratory Reference Values for Serum Testosterone

"Waking up" the sleeping metaphor of normality in connection to intersex or DSD: a scoping review of medical literature

The aim of the study is to encourage a critical debate on the use of normality in the medical literature on DSD or intersex. For this purpose, a scoping review was conducted to identify and map the various ways in which "normal" is used in the medical literature on DSD between 2016 and 2020. We identified 75 studies, many of which were case studies highlighting rare cases of DSD, others, mainly retrospective observational studies, focused on improving diagnosis or treatment. The most common use of the adjective normal was in association with phenotypic sex. Overall, appearance was the most commonly cited criteria to evaluate the normality of sex organs. More than 1/3 of the studies included also medical photographs of sex organs. This persistent use of normality in reference to phenotypic sex is worrisome given the long-term medicalization of intersex bodies in the name of a "normal" appearance or leading a "normal" life. Healthcare professionals should be more careful about the ethical implications of using photographs in publications given that many intersex persons describe their experience with medical photography as dehumanizing.

Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology

According to the free hormone hypothesis, biological activity of a certain hormone is best reflected by free rather than total hormone concentrations. A crucial element in this theory is the presence of binding proteins, which function as gatekeepers for steroid action. For testosterone, tissue exposure is governed by a delicate equilibrium between free and total testosterone which is determined through interaction with the binding proteins sex hormone-binding globulin and albumin. Ageing, genetics and various pathological conditions influence this equilibrium, hereby possibly modulating hormonal exposure to the target tissues. Despite ongoing controversy on the subject, strong evidence from recent in vitro, in vivo and human experiments emphasizes the relevance of free testosterone. Currently, however, clinical possibilities for free hormone diagnostics are limited. Direct immunoassays are inaccurate, while gold standard liquid chromatography with tandem mass spectrometry (LC-MS/MS) coupled equilibrium dialysis is not available for clinical routine. Calculation models for free testosterone, despite intrinsic limitations, provide a suitable alternative, of which the Vermeulen calculator is currently the preferred method. Calculated free testosterone is indeed associated with bone health, frailty and other clinical endpoints. Moreover, the added value of free testosterone in the clinical diagnosis of male hypogonadism is clearly evident. In suspected hypogonadal men in whom borderline low total testosterone and/or altered sex hormone-binding globulin levels are detected, the determination of free testosterone avoids under- and overdiagnosis, facilitating adequate prescription of hormonal replacement therapy. As such, free testosterone should be integrated as a standard biochemical parameter, on top of total testosterone, in the diagnostic workflow of male hypogonadism.

Effects of dietary supplementation of different oils and conjugated linoleic acid on the reproductive and metabolic aspects of male mice

The present study was carried out to examine first, if diets enriched with 320 g of the base diet with common dietary oils including fish oil, olive oil, hydrogenated sunflower seed (H-SFS) oil, flaxseed oil and sunflower seed oil (SFS) could induce weight gain and alter reproductive and metabolic characteristics of male mice. Second, whether the addition of conjugated linoleic acid (CLA, 10% of the diet) could ameliorate any negative effects. In this cross-sectional study, 90 four-week-old male NMRI mice were used in two consecutive experiments. A high level of dietary oils negatively affected some reproductive and metabolic characteristics of male mice (p < 0.05), specifically, sunflower seed oil enrichment resulted in higher HDL levels and apoptosis of germinal epithelial cells. An olive oil-enriched diet caused an increase in plasma triglyceride concentrations and germinal cell apoptosis, as well as a decrease in sperm concentration and perturbed spermatogenesis. When CLA was fed in conjunction with dietary oils it successfully mitigated some of the negative reproductive and metabolic characteristics. We conclude that male reproductive processes are affected by high dietary oils, even before signs of obesity are evident. Inclusion of dietary CLA may provide some benefit to offset negative effects, although further studies are required.

Clinical utility of serum 17-hydroxyprogesterone as a marker for medical therapy for male infertility: recommendations based on clinical scenarios

Traditional serum hormone testing in the evaluation of male infertility consists of testosterone, follicle-stimulating hormone, luteinizing hormone, and estradiol. Based on these values, medical therapy is often initiated in an attempt to increase intratesticular testosterone levels and, in turn, promote spermatogenesis. While this hormone panel provides serum testosterone levels, it does not evaluate intratesticular testosterone, obviously an important factor that is critical for spermatogenesis. 17-hydroxyprogesterone (17-OHP) is an intermediate in the steroidal pathway of cholesterol to testosterone conversion that has recently demonstrated promise as an accurate serum biomarker for intratesticular testosterone. At present, 17-OHP has not been widely adopted as a clinical tool in the evaluation of male infertility, which likely stems, in part, from a lack of concrete indications for its use. In this review, we present five commonly encountered scenarios of male infertility where the utilization of 17-OHP has aided in the management and provided a more personalized approach to treatment.

Is a fasting testosterone level really necessary for the determination of androgen status in men?

BACKGROUND

As circulating testosterone may be suppressed in the post-prandial state, it has been recommended that measurements are carried out with the patient fasted.

OBJECTIVES

In this regard, we assessed the effect of fasting/non-fasting status on total testosterone (T) levels in men.

MATERIALS AND METHODS

Data was collected in a single UK Hospital in men with two serum T requests taken within a 6-month period of each other and sampled at a time of day ≤ 2 h apart. Three groups were established, with T levels compared via signed-rank test in men with both a fasting and non-fasting sample (Group 1; n = 69), and in men with paired non-fasting (Group 2; n = 126) and paired fasting (Group 3; n = 18) samples. The differences in T levels between the paired samples was compared between the three groups using the rank-sum test and also via multiple regression analysis with the groups factorised.

RESULTS

Median (Interquartile Range, IQR) age did not vary significantly between Groups 1, 2 and 3 at 49 (38-56), 51.5 (42-60) and 51.5 (40-59) years, respectively. No significant difference (p = 0.89) was found between the T levels in Group 1 with non-fasting (median (IQR) T = 11.1 (9.3-13.6) nmol/L) versus fasting samples T = 10.8 (8.9-14.1) nmol/L). Paired T levels did not significantly differ in each of the other two groups (2 and 3). There was no significant association between the differences in paired T levels between the three groups, even when the model was adjusted for age and time, with Group 1 (as reference) versus Group 2 (p = 0.79) and versus Group 3 (p = 0.63).

DISCUSSION

We found no significant differences between fasting and non-fasting T levels. A definitive confirmatory study is required to determine whether fasting status is necessary to diagnose hypogonadism.

CONCLUSION

Non-requirement of fasting status when checking testosterone levels would remove a major hurdle in the diagnosis of hypogonadism.

Method for Simultaneous Determination of Free Concentration, Total Concentration, and Plasma Binding Capacity in Clinical Samples

Most quantitative research methods are based on measuring either the total or the free concentration of an analyte in a sample. However, this is often insufficient for the study of complex biological systems. The main objective of this research was to develop new methods for providing more information from samples: the free concentration (C_f), the total concentration (C_t), and the plasma binding capacity (PBC). Samples were processed using microextraction and ultrafiltration. For each of these techniques, two quantification procedures were used: addition of isotopically labeled standard and repeated analysis of the same sample. The new methods were validated by analyzing clinical samples and samples with known concentrations. Methods based on addition of labeled compound were found to be the fastest, and most reproducible. For analysis of clinical samples, methods based on microextraction were more sensitive and more accurate than those based on ultrafiltration. For analysis of pooled plasma samples, the overall accuracy of all approaches to determine PBC, testosterone C_f, and testosterone C_t was between 94 and 109%, 87-113%, and 94-122% respectively. The new approach goes beyond a simple concentration measurement, giving more information from clinical samples, with great potential for personalizing drug dosage and therapy to the needs of individual patients.

Serum Testosterone and Cortisol Concentrations After Single-Dose Administration of 100-Mg Transdermal Testosterone in Healthy Men

The growing interest in testosterone's effects on men's social behaviors, in particular aggressive, risk-taking, or status maintenance behaviors, is accompanied by a paucity of dose-dependent pharmacokinetic data. Examining the neurophysiological effects of transdermal testosterone typically includes a 4h delay before further brain-behavior measurements. Nevertheless, high heterogeneity regarding the timing of follow-up measurements and dosage remains. In a double-blind placebo-controlled design, we examined the short-term pharmacokinetic profile of 100-mg transdermal testosterone (Testotop^®) to determine the optimal time for detecting testosterone-mediated effects. Across two studies, 35 healthy men received a single dose of testosterone and placebo in two separate sessions. In study one (n = 16), serum testosterone and cortisol were assessed serially every 30 min up to 2 h posttreatment. In study two (n = 19), we assessed serum testosterone and cortisol at baseline, 2 h, and 4.15 h (255 min) posttreatment. Relative to baseline and placebo, transdermal testosterone significantly increased total serum testosterone concentrations 90 min posttreatment, reaching maximum concentration between 2 h and 3 h posttreatment. Albeit elevated, serum testosterone levels gradually decreased between 2 h and 4 h following treatment. Transdermal testosterone did not suppress cortisol release. Instead, cortisol concentrations decreased according to cortisol's known circadian rhythm. Unlike previous findings showing significant testosterone concentration increases as soon as 60 min and as late as 3 h post 150-mg testosterone treatment, our 100-mg testosterone manipulation significantly increased testosterone concentrations 90 min following treatment. These pharmacokinetic data are important in facilitating the optimization of timing parameters for future testosterone challenge studies.

Relation of Testosterone Normalization to Mortality and Myocardial Infarction in Men With Previous Myocardial Infarction

The effect of normalization of serum testosterone levels with testosterone replacement therapy (TRT) in patients with a history of myocardial infarction (MI) is unknown. The objective of this study was to determine the incidence of recurrent MI and all-cause mortality in subjects with a history of MI and low total testosterone (TT) with and without TRT. We retrospectively examined 1,470 men with documented low TT levels and previous MI, categorized into Gp1: TRT with normalization of TT levels (n = 755) Gp2: TRT without normalization of TT levels (n = 542), and Gp3: no TRT (n = 173). The association of TRT with all-cause mortality and recurrent MI was compared using propensity score-weighted Cox proportional hazard models. All-cause mortality was lower in Gp1 versus Gp2 (hazard ratio [HR] 0.76, confidence interval [CI] 0.64 to 0.90, p = 0.002), and Gp1 versus Gp3 (HR 0.76, CI 0.60 to 0.98, p = 0.031). There was no significant difference in the risk of death between Gp2 versus Gp3 (HR 0.97, CI 0.76 to 1.24, p = 0.81). Adjusted regression analyses showed no significant differences in the risk of recurrent MI between groups (Gp1 vs Gp3, HR 0.79, CI 0.12 to 5.27, p = 0.8; Gp1 vs Gp2 HR 1.10, CI 0.25 to 4.77, p = 0.90; Gp2 vs Gp3 HR 0.58, CI 0.08 to 4.06, p = 0.58). In conclusion, in a large observational cohort of male veterans with previous MI, normalization of TT levels with TRT was associated with decreased all-cause mortality compared with those with non-normalized TT levels and the untreated group. Furthermore, in this high-risk population, TRT was not associated with an increased risk of recurrent MI.

Assessment of free testosterone concentration

Testosterone (T) is strongly bound to sex hormone binding globulin and measurement of free T may be more appropriate than measuring total serum T, according to the free hormone theory. This view remains controversial and it has its detractors who claim that little extra benefit is gained than simply measuring total T, but it is endorsed by recent clinical practice guidelines for investigation of androgen disorders in both men and women. Free T measurement is very challenging. The gold standard equilibrium dialysis methods are too complex for use in routine clinical laboratories, assays are not harmonized and consequently there are no common reference intervals to aid result interpretation. The algorithms derived for calculating free T are inaccurate because they were founded on faulty models of testosterone binding to SHBG, however they can still give clinically useful results. To negate the effects of differences in binding protein constants, some equations for free T have been derived from accurate measurement of testosterone in large population studies, however a criticism is that the equations may not hold true in different patient populations. The free androgen index is not recommended for use in men because of inaccuracy at extremes of SHBG concentration, and in women it can also give inaccurate results when SHBG concentrations are low. If the free hormone hypothesis is to be believed, then calculated free testosterone may offer the best way forward but better equations are needed to improve accuracy and these should be derived from detailed knowledge of testosterone binding to SHBG. There is still much work to be done to improve harmonization of T and SHBG assays between laboratories because these can have a profound effect on the equations used to calculate free testosterone.

Short-Term Exercise Training Inconsistently Influences Basal Testosterone in Older Men: A Systematic Review and Meta-Analysis

Background: The age-associated decrease in testosterone is one mechanism suggested to accelerate the aging process in males. Therefore, approaches to increase endogenous testosterone may be of benefit. The aim of this paper was to undertake a Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-accordant meta-analysis concerning the effect of exercise on total (TT), bioavailable (bio-T), free (free-T), and salivary (sal-T) testosterone in older males. Methods: Databases were searched up to and including 20th February 2018 for the terms "testosterone AND exercise AND aging AND males," "testosterone AND exercise AND old AND males," "testosterone AND training AND aging AND males," and "testosterone AND training AND old AND males". From 1259 originally identified titles, 22 studies (randomized controlled trials; RCTs; n = 9, and uncontrolled trials; UCTs; n = 13) were included which had a training component, participants ≥60 years of age, and salivary or serum testosterone as an outcome measure. Meta-analyses were conducted on change to testosterone following training using standardized difference in means (SDM) and random effects models. Results: The overall SDM for endurance training, resistance training, and interval training was 0.398 (95% CI = 0.034-0.761; P = 0.010), -0.003 (95% CI = -0.330-0.324; P = 0.986), and 0.283 (95% CI = 0.030-0.535; P = 0.028), respectively. Resistance training exhibited a qualitative effect of hormone fraction whereby free-T resulted in the greatest SDM (0.253; 95% CI = -0.043-0.549; P = 0.094), followed by TT (0.028; 95% CI = -0.204-0.260; P = 0.813), and resistance training negatively influenced bio-T (-0.373; 95% CI = -0.789-0.042; P = 0.078). Due to the small number of studies, subgroup analysis was not possible for endurance training and interval training studies. Conclusions: Data from the present investigation suggests that resistance training does not significantly influence basal testosterone in older men. Magnitude of effect was influenced by hormone fraction, even within the same investigation. Aerobic training and interval training did result in small, significant increases in basal testosterone. The magnitude of effect is small but the existing data are encouraging and may be an avenue for further research.

A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications

In the circulation, testosterone and other sex hormones are bound to binding proteins, which play an important role in regulating their transport, distribution, metabolism, and biological activity. According to the free hormone hypothesis, which has been debated extensively, only the unbound or free fraction is biologically active in target tissues. Consequently, accurate determination of the partitioning of testosterone between bound and free fractions is central to our understanding of how its delivery to the target tissues and biological activity are regulated and consequently to the diagnosis and treatment of androgen disorders in men and women. Here, we present a historical perspective on the evolution of our understanding of the binding of testosterone to circulating binding proteins. On the basis of an appraisal of the literature as well as experimental data, we show that the assumptions of stoichiometry, binding dynamics, and the affinity of the prevailing models of testosterone binding to sex hormone-binding globulin and human serum albumin are not supported by published experimental data and are most likely inaccurate. This review offers some guiding principles for the application of free testosterone measurements in the diagnosis and treatment of patients with androgen disorders. The growing number of testosterone prescriptions and widely recognized problems with the direct measurement as well as the computation of free testosterone concentrations render this critical review timely and clinically relevant.

Normalization of Testosterone Levels After Testosterone Replacement Therapy Is Not Associated With Reduced Myocardial Infarction in Smokers

Objective

To examine the effect of cigarette smoking (CS) status and total testosterone (TT) levels after testosterone replacement therapy (TRT) on all-cause mortality, myocardial infarction (MI), and stroke in male smokers and nonsmokers without history of MI and stroke.

Participants and Methods

Data from 18,055 males with known CS status and low TT levels who received TRT at the Veterans Health Administration between December 1, 1999, and May 31, 2014, were grouped into (1) current smokers with normalized TT, (2) current smokers with nonnormalized TT, (3) nonsmokers with normalized TT, and (4) nonsmokers with nonnormalized TT. Combined effect of CS status and TT level normalization after TRT on all-cause mortality, MI, and stroke was compared using propensity score–weighted Cox proportional hazard models.

Results

Normalization of serum TT levels in nonsmokers was associated with a significant decrease in all-cause mortality (hazard ratio [HR]=0.526; 95% CI, 0.477-0.581; P<.001) and MI (HR=0.717; 95% CI, 0.522-0.986; P<.001). Among current smokers, normalization of serum TT levels was associated with a significant decrease in only all-cause mortality (HR=0.563; 95% CI, 0.488-0.649; P<.001) without benefit in MI (HR=1.096; 95% CI, 0.698-1.720; P=.69). Importantly, compared with nonsmokers with normalized TT, all-cause mortality (HR=1.242; 95% CI, 1.104-1.396; P<.001), MI (HR=1.706; 95% CI, 1.242-2.342; P=.001), and stroke (HR=1.590; 95% CI, 1.013-2.495; P=.04) were significantly higher in current smokers with normalized TT.

Conclusion

We conclude that active CS may negate the protective effect of testosterone level normalization on all-cause mortality and MI after TRT.

Normalization of Testosterone Levels After Testosterone Replacement Therapy Is Associated With Decreased Incidence of Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most common cardiac dysrhythmia associated with significant morbidity and mortality. Several small studies have reported that low serum total testosterone (TT) levels were associated with a higher incidence of AF. In contrast, it is also reported that anabolic steroid use is associated with an increase in the risk of AF. To date, no study has explored the effect of testosterone normalization on new incidence of AF after testosterone replacement therapy (TRT) in patients with low testosterone.

Methods and Results

Using data from the Veterans Administrations Corporate Data Warehouse, we identified a national cohort of 76 639 veterans with low TT levels and divided them into 3 groups. Group 1 had TRT resulting in normalization of TT levels (normalized TRT), group 2 had TRT without normalization of TT levels (nonnormalized TRT), and group 3 did not receive TRT (no TRT). Propensity score–weighted stabilized inverse probability of treatment weighting Cox proportional hazard methods were used for analysis of the data from these groups to determine the association between post‐TRT levels of TT and the incidence of AF. Group 1 (40 856 patients, median age 66 years) had significantly lower risk of AF than group 2 (23 939 patients, median age 65 years; hazard ratio 0.90, 95% CI 0.81–0.99, P=0.0255) and group 3 (11 853 patients, median age 67 years; hazard ratio 0.79, 95% CI 0.70–0.89, P=0.0001). There was no statistical difference between groups 2 and 3 (hazard ratio 0.89, 95% CI 0.78– 1.0009, P=0.0675) in incidence of AF.

Conclusions

These novel results suggest that normalization of TT levels after TRT is associated with a significant decrease in the incidence of AF.

Four Thrombotic Events Over 5 Years, Two Pulmonary Emboli and Two Deep Venous Thrombosis, When Testosterone-HCG Therapy Was Continued Despite Concurrent Anticoagulation in a 55-Year-Old Man With Lupus Anticoagulant

BACKGROUND

When exogenous testosterone or treatments to elevate testosterone (human chorionic gonadotropin [HCG] or Clomid) are prescribed for men who have antecedent thrombophilia, deep venous thrombosis and pulmonary embolism often occur and may recur despite adequate anticoagulation if testosterone therapy is continued.

CASE PRESENTATION

A 55-year-old white male was referred to us because of 4 thrombotic events, 3 despite adequate anticoagulation over a 5-year period. We assessed interactions between thrombophilia, exogenous testosterone therapy, and recurrent thrombosis. In 2009, despite low-normal serum testosterone 334 ng/dL (lower normal limit [LNL] 300 ng/dL), he was given testosterone (TT) cypionate (50 mg/week) and human chorionic gonadotropin (HCG; 500 units/week) for presumed hypogonadism. Ten months later, with supranormal serum T (1385 ng/dL, upper normal limit [UNL] 827 ng/dL) and estradiol (E2) 45 pg/mL (UNL 41 pg/mL), he had a pulmonary embolus (PE) and was then anticoagulated for 2 years (enoxaparin, then warfarin). Four years later, on TT-HCG, he had his first deep venous thrombosis (DVT). TT was stopped and HCG continued; he was anticoagulated (enoxaparin, then warfarin, then apixaban, then fondaparinux). One year after his first DVT, on HCG, still on fondaparinux, he had a second DVT (5/315), was anticoagulated (enoxaparin + warfarin), with a Greenfield filter placed, but 8 days later had a second PE. Thrombophilia testing revealed the lupus anticoagulant. After stopping HCG, and maintained on warfarin, he has been free of further DVT-PE for 9 months.

CONCLUSION

When DVT-PE occur on TT or HCG, in the presence of thrombophilia, TT-HCG should be stopped, lest DVT-PE reoccur despite concurrent anticoagulation.

Controversies and Advances With Testosterone Therapy: A 40-Year Perspective

Testosterone therapy (TTh) has become highly controversial. There are important health consequences of testosterone deficiency, and meaningful benefits with treatment. There is level 1 evidence that TTh improves sexual function and desire, body composition, and bone density. Concerns regarding cardiovascular risk were based on two deeply flawed retrospective studies and are contradicted by dozens of studies showing cardiovascular benefits of TTh or higher endogenous testosterone, including placebo-controlled studies in men with known heart disease (angina, heart failure). Prostate cancer should no longer be considered a risk of TTh. Testosterone is neither scourge nor panacea--it is just good medicine.

Controversies in testosterone supplementation therapy

Testosterone has now become one of the most widely used medications throughout the world. The rapid growth of the testosterone market in the past 10 years is due to many factors. We currently have a worldwide aging population. In the US, the number of men 65 years old or older is increasing 2–3 times faster than the number of men younger than 65 years. In addition, poor general health and certain medical conditions such as diabetes/metabolic syndrome (MetS), cardiovascular disease (CVD), and osteoporosis have been associated with low serum testosterone levels.123 There are now fewer concerns regarding the development of prostate cancer (PCa) after testosterone therapy, making it a more attractive treatment option. Finally, the introduction of different forms of testosterone supplementation therapy (TST) with increased promotion, marketing, and direct-to-consumer advertising is also driving market growth. As the demand for TST continues to grow, it is becoming more important for clinicians to understand how to diagnose and treat patients with low testosterone.

The practical management of testosterone deficiency in men

Despite increased global interest in testosterone deficiency in men and its treatment with testosterone therapy, practical aspects of care remain confusing to many practitioners. Testosterone deficiency can result from testicular dysfunction (primary hypogonadism) or hypothalamic-pituitary dysfunction (secondary hypogonadism), and be congenital or acquired. Sexual and nonsexual symptoms of testosterone deficiency can negatively affect quality of life and cause considerable general health concerns. Investigation of testosterone deficiency should be undertaken in men with symptoms of reduced libido, erectile dysfunction, depression, fatigue, poor concentration, and poor memory. Total and free testosterone are the most frequently used tests and evaluating serum concentrations of luteinizing hormone aids determination of primary versus secondary testosterone deficiency. Multiple formulations of testosterone therapy are available, but symptomatic benefits might not manifest for several weeks to many months; long-acting formulations are convenient and improve compliance. Concerns regarding cardiovascular and prostate cancer risks are not supported by current evidence, monitoring during therapy is mandatory. On balance, testosterone therapy can be considered a safe and effective treatment for testosterone deficiency.

Normalization of testosterone level is associated with reduced incidence of myocardial infarction and mortality in men

AIMS

There is a significant uncertainty regarding the effect of testosterone replacement therapy (TRT) on cardiovascular (CV) outcomes including myocardial infarction (MI) and stroke. The aim of this study was to examine the relationship between normalization of total testosterone (TT) after TRT and CV events as well as all-cause mortality in patients without previous history of MI and stroke.

METHODS AND RESULTS

We retrospectively examined 83 010 male veterans with documented low TT levels. The subjects were categorized into (Gp1: TRT with resulting normalization of TT levels), (Gp2: TRT without normalization of TT levels) and (Gp3: Did not receive TRT). By utilizing propensity score-weighted Cox proportional hazard models, the association of TRT with all-cause mortality, MI, stroke, and a composite endpoint was compared between these groups. The all-cause mortality [hazard ratio (HR): 0.44, confidence interval (CI) 0.42-0.46], risk of MI (HR: 0.76, CI 0.63-0.93), and stroke (HR: 0.64, CI 0.43-0.96) were significantly lower in Gp1 (n = 43 931, median age = 66 years, mean follow-up = 6.2 years) vs. Gp3 (n = 13 378, median age = 66 years, mean follow-up = 4.7 years) in propensity-matched cohort. Similarly, the all-cause mortality (HR: 0.53, CI 0.50-0.55), risk of MI (HR: 0.82, CI 0.71-0.95), and stroke (HR: 0.70, CI 0.51-0.96) were significantly lower in Gp1 vs. Gp2 (n = 25 701, median age = 66 years, mean follow-up = 4.6 years). There was no difference in MI or stroke risk between Gp2 and Gp3.

CONCLUSION

In this large observational cohort with extended follow-up, normalization of TT levels after TRT was associated with a significant reduction in all-cause mortality, MI, and stroke.

Testosterone, thrombophilia, thrombosis

We screened previously undiagnosed thrombophilia (V Leiden-prothrombin mutations, Factors VIII and XI, homocysteine, and antiphospholipid antibody [APL] syndrome) in 15 men and 2 women with venous thromboembolism (VTE) or osteonecrosis 7 months (median) after starting testosterone therapy (TT), gel (30-50 mg/d), intramuscular (100-400 mg/wk), or human chorionic gonadotropin (HCG) (6000 IU/wk). Thrombophilia was studied in 2 healthy control groups without thrombosis (97 normal controls, 31 subjects on TT) and in a third control group (n = 22) with VTE, not on TT. Of the 17 cases, 76% had ≥1 thrombophilia vs 19% of 97 normal controls (P < 0.0001), vs 29% of 31 TT controls (P = 0.002). Cases differed from normal controls by Factor V Leiden (12% vs 0%, P = 0.021), by high Factor VIII (>150%) (24% vs 7%, P = 0.058), by high homocysteine (29% vs 5%, P = 0.007), and from both normal and TT controls for APL syndrome (18% vs 2%, P = 0.023, vs 0%, P = 0.04). Despite adequate anticoagulation with TT continued after the first deep venous thrombosis-pulmonary embolus (DVT-PE), 1 man sustained 3 DVT-PEs 5, 8, and 11 months later and a second man had 2 DVT-PEs 1 and 2 months later. Of the 10 cases with serum T measured on TT, 6 (60%) had supranormal T (>800 ng/dL) and of 9 with estradiol measured on TT, 7 (78%) had supranormal levels (>42.6 pg/mL). TT interacts with thrombophilia leading to thrombosis. TT continuation in thrombophilic men is contraindicated because of recurrent thrombi despite anticoagulation. Screening for thrombophilia before starting TT should identify subjects at high risk for VTE with an adverse the risk to benefit ratio for TT.

Testosterone replacement therapy: who to evaluate, what to use, how to follow, and who is at risk?

BACKGROUND

Hypogonadism, defined as a low serum testosterone in the presence of signs and symptoms, is common, particularly in aging men. Testosterone supplementation therapy (TST) is the standard treatment for male hypogonadism. It has been demonstrated to have a significant impact on the signs and symptoms of hypogonadism, but there are concerns about the increase in TST and its potential adverse effects, particularly cardiovascular effects.

OBJECTIVE

This review presents health care providers with current information regarding the prevalence and impact of hypogonadism, as well as the diagnosis, evaluation, and treatment of hypogonadism. The beneficial and potential adverse effects are reviewed with a discussion on the current cardiovascular controversy.

METHODS

We reviewed current and "landmark" articles in the English-language literature pertaining to hypogonadism, its prevalence, etiologies, presentation, evaluation, and treatment.

RESULTS

Authorities in the field have offered guidelines and recommendations regarding the diagnosis, evaluation, and management of hypogonadism. Although there is a consensus as to the definition of hypogonadism as the presence of a low serum testosterone with signs and symptoms of hypogonadism, there is variability in the definition of "low testosterone." Various testosterone formulations exist, differing in route and frequency of administration as well as in side-effect profiles. Testosterone supplementation therapy should be continued in individuals demonstrating an improvement in signs and symptoms, which may take 3 months to a year for maximum response. Individuals treated with TST require monitoring for adverse effects. Further studies are needed to determine the impact of TST on cardiovascular health.

CONCLUSION

Hypogonadism is common, particularly in aging men. Symptomatic individuals who have no contraindications to TST should be offered treatment. A careful assessment of treatment response after adequate titration and duration of therapy as well as monitoring for adverse effects is essential in treating patients for hypogonadism. Although hypogonadism is associated with increased all-cause and cardiovascular-related mortality, controversy exists regarding the impact of TST on cardiovascular risk, highlighting the need for further studies.

Testosterone therapy, thrombosis, thrombophilia, cardiovascular events

There are similar time intervals between starting testosterone therapy (TT) and development of thrombotic (~4.5 months) or cardiovascular (CVD) events (~3 months) which may, speculatively, reflect a shared pathophysiology. We have described thrombotic events 5 months (median) after starting TT in 38 men and 4 women, including 27 with deep venous thrombosis-pulmonary embolism, 12 with osteonecrosis, 1 with central retinal vein thrombosis, 1 with amaurosis fugax, and 1 with spinal cord infarction. In 8 men whose TT was continued, second thrombotic events occurred despite adequate anticoagulation with Coumadin in 8 men, 3 of whom had a third thrombotic event. Of these 42 cases, 40 had measures of thrombophilia-hypofibrinolysis, and 39 were found to have previously undiagnosed thrombophilia-hypofibrinolysis. Before beginning TT, especially in men with previous history of thrombotic events, we suggest that, at a minimum, measurements be made for the Factor V Leiden and Prothrombin mutations, Factors VIII and XI, and homocysteine, to identify men who should not receive TT. We need prospective data focused on whether there should be pre-TT screening based on history of previous venous thromboembolism or for all subjects for major gene thrombophilias. To better resolve questions about TT and all cause and cardiovascular morbidity and mortality and thrombosis, a long term, prospective, randomized, blinded study following the example of the Women's Health Initiative is needed. While we wait for prospective placebo-controlled TT outcome data, TT should be restricted to men with well-defined androgen deficiency syndromes.

Commentary: Who is a candidate for testosterone therapy? A synthesis of international expert opinions

INTRODUCTION

Despite increasing use of testosterone therapy (TTh) for men with testosterone deficiency (TD), there remains uncertainty determining who is a candidate for treatment.

AIM

The aim if this study was to report the opinions of international experts on TTh, as initially presented at the meeting of the World Meeting on Sexual Medicine in Chicago, United States in August 2012.

METHODS

Expert responses to questions regarding the diagnosis of TD based on their own clinical and research experience.

RESULTS

All experts emphasized the primacy of symptoms for the diagnosis of TD. Total testosterone (T) thresholds used to identify TD ranged from 350 ng/dL to 400 ng/dL (12-14 nmol/L); however, experts emphasized the diagnostic limitations of this test. Free T was obtained by all, with some valuing this test more than total T for clinical decision making. Only one expert routinely used a screening questionnaire. None used age-adjusted values. Bioavailable T and the free androgen index were not used. Luteinizing hormone (LH) and sex hormone-binding globulin levels were routinely obtained at evaluation. Additional supportive evidence for TD diagnosis included small testicular volume, high androgen receptor CAG repeats, elevated LH, and presence of diabetes or metabolic syndrome. Two T tests were generally obtained but not always required. Some experts did not require morning testing in men 50 years and older. All monitored prostate-specific antigen and hematocrit after initiation of TTh. All but one expert would consider a trial of TTh to a symptomatic man with total T within the normal range. Recent studies suggesting increased cardiovascular risk with T therapy were not found to be credible.

CONCLUSIONS

Determining who is a candidate for TTh requires clinical assessment based on symptoms and signs, with confirmatory laboratory evaluation. These expert opinions differed from some published guidelines by the emphasis on symptoms as paramount, recognition of the limitations of total T as a diagnostic test, and the potential utility of a therapeutic trial in symptomatic cases with normal total T concentrations.

Testosterone lab testing and initiation in the United Kingdom and the United States, 2000 to 2011

CONTEXT

New formulations, increased marketing, and wider recognition of declining testosterone levels in older age may have contributed to wider testosterone testing and supplementation in many countries.

OBJECTIVE

Our objective was to describe testosterone testing and testosterone treatment in men in the United Kingdom and United States.

DESIGN

This was a retrospective incident user cohort.

SETTING

We evaluated commercial and Medicare insurance claims from the United States and general practitioner healthcare records from the United Kingdom for the years 2000 through 2011.

PARTICIPANTS

We identified 410,019 US men and 6858 UK men who initiated a testosterone formulation as well as 1,114,329 US men and 66,140 UK men with a new testosterone laboratory measurement.

MAIN OUTCOME MEASURES

Outcome measures included initiation of any injected testosterone, implanted testosterone pellets, or prescribed transdermal or oral testosterone formulation.

RESULTS

Testosterone testing and supplementation have increased pronouncedly in the United States. Increased testing in the United Kingdom has identified more men with low levels, yet US testing has increased among men with normal levels. Men in the United States tend to initiate at normal levels more often than in the United Kingdom, and many men initiate testosterone without recent testing. Gels have become the most common initial treatment in both countries.

CONCLUSIONS

Testosterone testing and use has increased over the past decade, particularly in the United States, with dramatic shifts from injections to gels. Substantial use is seen in men without recent testing and in US men with normal levels. Given widening use despite safety and efficacy questions, prescribers must consider the medical necessity of testosterone before initiation.

Subcutaneous pellet testosterone replacement therapy: the "first steps" in treating men with spinal cord injuries

The authors describe the case of a 36-year-old man who presented with hormone level concerns 6 months after a rock climbing accident that resulted in paraplegia. Hypogonadism was diagnosed, and the patient received subcutaneous pellet testosterone replacement therapy. Within 6 months, the patient had substantial improvement in muscle function and was able to take several steps with the assistance of crutches or a walker. This case highlights the potential improvement in quality of life and overall prognosis resulting from the subcutaneous pellet form of testosterone when used as part of the overall treatment plan in such patients. Considering the overwhelming preponderance of hypogonadism in men with spinal cord injuries, the standard of care for such patients should include screening, laboratory hormone evaluation, and prompt treatment for testosterone deficiency.

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.

[Association of nocturnal penile rigidity with testosterone, metabolic syndrome, and other variables: a prospective cross-sectional pilot study]

INTRODUCTION

The aim was to study whether nocturnal penile rigidity (NPTR) correlates with metabolic syndrome (MetS) and testosterone in men consulting for erectile dysfunction (ED).

MATERIAL AND METHODS

234 men were included in a prospective, cross-sectional pilot study. Serum total and bioavailable testosterone and other biochemical constituents were measured and compared with NPTR. Patients were classified by normal or low/abnormal penile rigidity (abnormal meaning predominant organic component of ED) and presence or absence of MetS to test the hypothesized correlations.

RESULTS

Application of the logistic regression model to rigidity as the dependent variable showed the risk of low penile rigidity to be significantly lower for patients with higher total (OR=0.96, 95% CI=0.92-0.99) or bioavailable testosterone (OR=0.91, 95% CI=0.84-0.99). Patients with testosterone levels between 8 and 12 mmol/L had a quadrupled risk of low penile rigidity compared with patients with higher levels (>12 mmol/L) (OR=3.96, 95% CI=1.89-8.31). Considering men without MetS, age and body mass index were associated as significant factors for low penile rigidity: age increased risk by 8% (OR=1.08, 95% CI=1.03-1.13) and BMI increased it by 18% (OR=1.18, 95% CI=1.01-1.38).

CONCLUSION

Testosterone levels are weakly associated with penile rigidity and disappear when associated with MetS.

Testosterone replacement therapy for late-onset hypogonadism: current trends in Korea

Testosterone levels in men older than 40 years can decrease at a rate of 1%-2% per year, and reports show that more than 50% of 80-year-old men have testosterone levels consistent with hypogonadism. Late-onset hypogonadism (LOH) is a clinical and biochemical syndrome associated with advancing age and characterized by typical symptoms of serum testosterone deficiency. In recent decades, the concept of LOH in ageing men has become familiar in European countries and the United States. It is also a topic of interest and debate throughout Korea. However, most of the data regarding advantages or disadvantages of testosterone replacement therapy (TRT) as treatment for LOH have been primarily obtained from studies on Western populations; therefore, studies of the effects of TRT in Asian men, who may have different serum testosterone compared to Western men, are needed. TRT is commonly prescribed in Korea, despite the paucity of studies on the effects of TRT in Asian populations. Data from various TRT studies based on Korean have shown its efficacy in increasing serum testosterone levels and improving subjective symptoms as assessed by questionnaires. Currently, patches and short-acting intramuscular injections are displaced by gels and long-acting formulations. However, to prevent overdiagnosis and overtreatment, indication for TRT should include both low testosterone levels and symptoms and signs of hypogonadism.

Hormone treatment and muscle anabolism during aging: androgens

Aging is associated with a gradual decline in circulating testosterone concentrations and decreased musculature in men. While testosterone administration is often considered when symptoms of hypogonadism are presented, the long-term effects of androgen use on muscle physiology are not yet fully understood. The definition of hypogonadism in men remains obscure but is generally indicated by total testosterone concentrations less than a threshold value of 300-500 ng/dL. Androgen replacement therapy is generally safe in men and women with low endogenous testosterone concentrations. The development of selective androgen receptor modulators (SARMs) may provide additional options in treatment of hypogonadism while lowering the potential of side effects often associated with long-term androgen use. Androgen administration, either alone or in combination with other treatments, can be successful in improving muscle mass by increasing protein anabolism and reducing protein catabolism in men and women. Further research is necessary to optimize the anabolic and anticatabolic properties of androgens for treatment and prevention of muscle loss in men and women.

Current and future testosterone delivery systems for treatment of the hypogonadal male

BACKGROUND

Hypogonadism is manifest in all age groups, and a growing elderly population is requiring treatment for testosterone deficiency, presenting new safety challenges, as many of these individuals present with comorbidities and significant risk profiles.

OBJECTIVE

To discuss testosterone replacement modalities, their advantages and disadvantages, and provide a discussion of safety issues.

METHODS

We reviewed the literature regarding testosterone replacement therapy and have provided a summary of our most outstanding findings.

CONCLUSION

Potential benefits of testosterone replacement therapy include increased lean body mass, heightened libido, increased bone density and elevation of mood. Some disadvantages are clearly defined, while others require further investigation. Patient and physician must cooperate to agree on an individual patient's most appropriate and tolerable route of administration.

Hormonal evaluation of the infertile male: has it evolved?

An endocrinologic evaluation of patients who have male-factor infertility has clearly evolved and leads to specific diagnoses and treatment strategies in a large population of infertile men. A well-considered endocrine evaluation is especially essential with the ever-growing popularity of assisted reproductive techniques and continued refinements with intracytoplasmic sperm injection.

Menstrual cycle-related changes in circulating androgens in healthy women with self-reported normal sexual function

INTRODUCTION

There is currently neither a clinically useful, reliable and inexpensive assay to measure circulating levels of free testosterone (T) in the range observed in women, nor is there agreement on the serum free T threshold defining hypoandrogenism that is associated with female-impaired sexual function.

AIM

Following the Clinical and Laboratory Standards Institute guidelines, we generated clinically applicable ranges for circulating androgens during specific phases of the menstrual cycle in a convenience sample of 120 reproductive-aged, regularly cycling healthy European Caucasian women with self-reported normal sexual function.

METHODS

All participants were asked to complete a semistructured interview and fill out a set of validated questionnaires, including the Female Sexual Function Index, the Female Sexual Distress Scale, and the 21-item Beck's Inventory for Depression. Between 8 am and 10 am, a venous blood sample was drawn from each participant during the midfollicular (day 5 to 8), the ovulatory (day 13 to 15), and the midluteal phase (day 19 to 22) of the same menstrual cycle.

MAIN OUTCOME MEASURES

Serum levels of total and free testosterone, Delta(4)-androstenedione, dehydroepiandrosterone sulphate and sex hormone-binding globulin during the midfollicular, ovulatory and midluteal phase of the same menstrual cycle.

RESULTS

Total and free T levels showed significant fluctuations, peaking during the ovulatory phase. No significant variation during the menstrual cycle were observed for Delta(4)-androstenedione and dehydroepiandrosterone sulphate. Despite the careful selection of participants that yielded an homogeneous group of women without sexual disorders, we observed a wide range of distribution for each of the circulating androgens measured in this study.

CONCLUSIONS

This report provides clinically applicable ranges for androgens throughout the menstrual cycle in reproductive-aged, regularly cycling, young healthy Caucasian European women with self-reported normal sexual function.

The paradox dividing testosterone deficiency symptoms and androgen assays: a closer look at the cellular and molecular mechanisms of androgen action

INTRODUCTION

Central to the diagnosis and treatment of testosterone deficiency syndrome in the adult male is the remarkable paradox that there is a very poor correlation between the characteristic symptoms and levels of serum androgens.

AIM

Because androgen deficiency can be associated with severe symptomatology, as well as diverse conditions such as coronary heart disease, diabetes, and metabolic syndrome, the aim was to present an evidence-based working hypothesis to resolve this confusing clinical paradox.

METHODS

A review of the possible mechanisms in testosterone deficiency syndrome was carried out, and a hypothesis to explain this paradox and associated problems in the diagnosis and clinical management of androgen deficiency was established on the basis of a review of the literature.

MAIN OUTCOME MEASURES

The mechanisms by which androgen deficiency could arise were studied at five different levels: 1. Impaired androgen synthesis or regulation. 2. Increased androgen binding. 3. Reduced tissue responsiveness. 4. Decreased androgen receptor activity. 5. Impaired transcription and translation.

RESULTS

As with insulin in maturity onset diabetes mellitus, there can be both insufficient production and variable degrees of resistance to the action of androgens operating at several levels in the body simultaneously, with these factors becoming progressively worse with aging, adverse lifestyle, other disease processes, and a wide range of medications.

CONCLUSIONS

Using this model, androgen deficiency can be redefined as an absolute or relative deficiency of androgens or their metabolites according to the needs of that individual at that time in his life. There are important ways in which the considerations raised by this hypothesis affect the etiology, terminology, diagnosis, and treatment of androgen-deficient states.

The diagnosis of late life hypogonadism

The diagnosis of late life hypogonadism is controversial. For the purposes of discussion, it is suggested that treatment of late life hypogonadism requires the presence of symptoms, a low level of circulating free or bioavailable testosterone level and a positive response to treatment. While this may appear to be a radical proposal, we believe it represents the most rigorous scientific approach to the diagnosis of late life hypogonadism at the present time.

The burden of testosterone deficiency syndrome in adult men: economic and quality-of-life impact

INTRODUCTION

Testosterone deficiency syndrome (TDS) causes a wide range of symptoms that can lead to significant morbidity. Preliminary evidence has also linked TDS with premature mortality and with a number of comorbid diseases including diabetes and metabolic syndrome. Such associations can lead to substantial economic and quality-of-life implications, the magnitude of which remains largely unknown.

AIM

To review the economic and quality-of-life consequences of a largely untreated condition and to consider the likely health economic benefits of testosterone treatment.

METHODS

A systematic review of four main areas: epidemiological evidence of the magnitude of TDS, estimates of cost of illness, impact on quality-of-life, and cost-effectiveness of testosterone treatment.

MAIN OUTCOME MEASURE

Review of peer-reviewed literature.

RESULTS

The lack of clear universally accepted diagnostic criteria and the uncertainty surrounding the link between TDS and some of its consequences complicate the estimation of the burden of illness of TDS. Consequences of TDS that potentially lead to increased economic burden include depression, sexual dysfunction, mild cognitive impairment, osteoporosis, cardiovascular disease, and mortality. However, although good evidence exists demonstrating an association between TDS and sexual dysfunction and cognitive impairment, evidence is less strong for depression, the incidence of fractures and mortality, and highly controversial for cardiovascular disease. The consequences that are likely to impact on patients' quality of life include sexual function, energy levels, body composition, mood, and cognitive function.

CONCLUSION

Understanding the burden is only the first step decision makers need to take to decide whether to allocate scarce resources to treat the condition. To make informed decisions on when and who to treat information is also needed on the cost-effectiveness of available treatments. Such data would highlight the benefits of treatment of TDS to physicians, patients, and to society as a whole.

The validity of androgen assays

Problems in the measurement of androgens and in interpreting results have been reviewed and classified as follows: PREANALYTICAL FACTORS: The exact sampling conditions in relation to circadian and seasonal variations, diet, alcohol, physical activity and posture.

PHYSIOLOGICAL AND MEDICAL FACTORS

Androgen levels vary according to the patient's general health, stress, sexual activity and smoking habits. Analytical variables. Sample preservation and storage variables are often unknown. The different androgen assays used have widely differing accuracy and precision and are subject to large inter-laboratory variation, which especially in women and children can render the results of routinely available direct immunoassays meaningless.

INTERPRETATION OF RESULTS

Laboratory reference ranges vary widely, largely independent of methodology, and fail to take into account the log-normal distribution of androgen values, causing errors in clinical diagnosis and treatment. Other unknowns are antagonists such as SHBG, estrogens, catecholamines, cortisol, and anti-androgens. As well as age, androgen receptor polymorphisms play a major role in regulating androgen levels and resistance to their action.

CONCLUSIONS

Though laboratory assays can support a diagnosis of androgen deficiency in men, they should not be used to exclude it. It is suggested that there needs to be greater reliance on the history and clinical features, together with careful evaluation of the symptomatology, and where necessary a therapeutic trial of androgen treatment given.

A clinical paradigm for the combined management of androgen insufficiency and erectile dysfunction

Androgen insufficiency and erectile dysfunction are highly prevalent medical disorders in aging men who have associated multiple risk factors. Good clinical practice requires the use of appropriate strategies for patient- and goal-directed diagnosis and treatment. This article focuses on a rational, evidence based clinical management paradigm that combines diagnosis and treatment of men who have androgen insufficiency and erectile dysfunction.

REPORT: Canadian Society for the Study of the Aging Male: Response to Health Canada's Position Paper on Testosterone Treatment

INTRODUCTION

Testosterone treatment of older symptomatic men with reduced testosterone availability is increasing. There is an expanding body of literature to support such treatment in a large subset of aging men, but there has not yet been a long-term placebo-controlled double-blind study of several thousand men to confirm the efficacy and safety of this treatment as indicated by shorter-term studies. The absence of a long-term study has been used by governmental agencies as a limiting factor in providing full access and payment for this treatment in government-sponsored health care plans. Health Canada issued a testosterone analysis document to the pharmaceutical industry, the implications of which may make it more difficult for appropriate patients to receive such treatment. The Canadian Society for the Study of the Aging Male (CSSAM) believed it had an obligation to advocate on behalf of men requiring this treatment.

AIM

To provide an international consensus on the use of testosterone treatment in appropriately selected hypogonadal men.

MAIN OUTCOME MEASURE

To determine whether the literature supports the use of testosterone treatment in a selected population of hypogonadal men, to achieve consensus on this point among an international consulting group, and to transmit this view to health care workers and insuring and governmental agencies.

METHODS

Email communication among the consulting group to prepare a response to Health Canada, followed by a review of appropriate literature and international practice guidelines, incorporating the literature and guidelines together with the CSSAM letter and Health Canada's response.

RESULT

The literature and international guidelines support the initiation of testosterone therapy in symptomatic hypogonadal men, recognizing that there is no universal agreement on the criteria for the diagnosis of hypogonadism in each suspected case. The need for careful monitoring of such men is stressed.

CONCLUSION

CSSAM acted as an advocate for hypogonadal men who may benefit from treatment with testosterone. Short-term studies and 60 years of experience with testosterone therapy attest to its efficacy. Long-term studies are desirable, but it may take many years before results could be forthcoming. There is no evidence to suggest that testosterone treatment increases the risk of prostate cancer or cardiovascular disease. Current evidence suggests, in fact, that testosterone treatment may be cardioprotective. It is important to bring this information to the attention of governments and insuring agencies through the collaboration of groups devoted to the diagnosis and treatment of hypogonadal men.

Testosterone and erectile function: from basic research to a new clinical paradigm for managing men with androgen insufficiency and erectile dysfunction

OBJECTIVES

Androgens are essential for the development and growth of the penis, and they regulate erectile physiology by multiple mechanisms. Our goal is to provide a concise overview of the basic research and how this knowledge can be translated into a new clinical paradigm for patient management. In addition, this new paradigm may serve as a basis for stimulating constructive debate regarding the use of testosterone in men, and to promote new, innovative basic and clinical research to further understand the underlying mechanisms of androgen action in restoring erectile physiology.

METHODS

A literature review was performed utilizing the US National Library of Medicine's PubMed database.

RESULTS

On the basis of evidence derived from laboratory animal studies and clinical data, we postulate that androgen insufficiency disrupts cellular-signaling pathways and produces pathologic alterations in penile tissues, leading to erectile dysfunction. In this review, we discuss androgen-dependent cellular, molecular, and physiologic mechanisms modulating erectile function in the animal model, and the implication of this knowledge in testosterone use in the clinical setting to treat erectile dysfunction. The new clinical paradigm incorporates many of the consensed points of view discussed in traditional consensed algorithms exclusively designed for men with androgen insufficiency. There are, however, novel and innovative differences with this new clinical paradigm. This paradigm represents a fresh effort to provide mandatory and optional management strategies for men with both androgen insufficiency and erectile dysfunction.

CONCLUSIONS

The new clinical paradigm is evidence-based and represents one of the first attempts to address a logical management plan for men with concomitant hormonal and sexual health concerns.