Association of hypogonadism and type II diabetes in men attending an outpatient erectile dysfunction clinic

Men's health, low testosterone, and diabetes: individualized treatment and a multidisciplinary approach

Testosterone plays a critical role in male reproductive and metabolic functioning. Serum testosterone levels decrease with age, and low testosterone is associated with a variety of comorbidities, including insulin resistance, type 2 diabetes, obesity, metabolic syndrome, and cardiovascular disease. Men with type 2 diabetes have been shown to have significantly lower testosterone levels than men without diabetes. Several forms of testosterone replacement therapy (eg, oral, injectable, buccal, transdermal preparations) are available for use in the United States. The primary goals of testosterone therapy are to restore physiologic testosterone levels and reduce the symptoms of hypogonadism. Testosterone therapy may be a viable option in some men with diabetes and low testosterone; however, clinicians must be aware of contraindications to therapy (eg, prostate cancer and male breast cancer), implement appropriate monitoring procedures, and ensure that patient expectations are realistic regarding treatment outcome. Data suggest that testosterone therapy may have a positive effect on bones, muscles, erythropoiesis and anemia, libido, mood and cognition, penile erection, cholesterol, fasting blood glucose, glycated hemoglobin, insulin resistance, visceral adiposity, and quality of life. Sexual health may be a window into men's health; thus, more effective communication strategies are needed between clinicians and men with diabetes to ensure that sexual health topics are adequately addressed. Diabetes educators can play a key role in screening for low testosterone, providing relevant information to patients, and increasing clinician awareness of the need to address men's sexual health and implement appropriate strategies. Multidisciplinary care and individualized treatment are needed to optimize outcome.

Review type 2 diabetes mellitus and erectile dysfunction

INTRODUCTION

Diabetes mellitus (DM) is a major risk factor for the development of erectile dysfunction (ED). Although most diabetic ED cases are in patients with type 2 diabetes (T2DM), the majority of basic science studies examining mechanisms of diabetic ED have been conducted in animal models of type 1 diabetes.

AIM

Recently, however, clinical and laboratory-based studies have uncovered some key underlying factors of T2DM-associated ED, which we have compiled in this review of T2DM ED.

MAIN OUTCOME MEASURES

The outcomes discussed in this review include major mechanisms underlying T2DM, discussing both clinical and basic science studies.

METHODS

We conducted an extensive search of pertinent clinical and basic science literature using PUBMED.

RESULTS

Mechanisms causing ED in T2DM are multifactorial and often lead to resistance to current therapy. Systemic effects of hyperglycemia and hypogonadism contribute to the development of impaired vasodilatory signaling, smooth muscle cell hypercontractility, and veno-occlusive disorder in T2DM ED.

CONCLUSIONS

Understanding the different causes for ED in T2DM patients may allow targeted therapy for improved erectile function.

Why can patients with erectile dysfunction be considered lucky? The association with testosterone deficiency and metabolic syndrome

Metabolic syndrome (MetS) is a diagnostic category, based on a cluster of risk factors (hyperglycemia/diabetes, abdominal obesity, hypertriglyceridaemia, low HDL cholesterol and hypertension), which identifies subjects at high risk for forthcoming type 2 diabetes mellitus and cardiovascular (CV) diseases. Recently, a close association between MetS, erectile dysfunction (ED) and male hypogonadism has been reported. In patients with MetS, hypogonadism can exacerbate sexual dysfunction and arteriogenic ED because of its typical symptoms, such as decreased sexual desire and mood disturbances. On the other hand, hypogonadism per se has been associated with an increased risk of CV and overall mortality. Obesity and in particular central obesity is nowadays considered the most important determinant of MetS-induced hypogonadism whereas hypertension and diabetes play a major role in ED associated with MetS. This review analyses the current literature regarding the relationship between ED, MetS and hypogonadism emphasising the epidemiological and psychopathological aspects and stressing the concept that ED subjects are 'lucky', because ED offers a unique chance to undergo medical examination and therefore to improve not only their sexual but, most importantly, their overall health.

Type 2 diabetes-associated androgen alteration in patients with erectile dysfunction

Our objective was to assess the pattern of type-2 diabetes-associated androgen alteration in patients with erectile dysfunction (ED). A total of 127 diabetic male patients with ED were enrolled in this study. Erectile function was assessed using the International Index of Erectile Function (IIEF). At the time of assessment, patients were also interviewed and assessed for socio-demographic and medical history that includes duration and severity of diabetes mellitus (DM). Patients underwent routine laboratory investigations, in addition to total testosterone (T), dehydroepiandrosterone sulphate (DHEA-S) and insulin assessment. The mean age +/- SD was 53.8 +/- 9.3 years. Of patients 25.2% (n = 32/127), 6.3% (n = 8/127) and 31.5% (n = 40/127) had low total T, low DHEA-S and hyperinsulinaemia respectively. There were significant association between the increase in age and body mass index and the presence of low T level. Of the patients 37.5% (n = 12/32) with low T level had glycosylated haemoglobin (HbA1c) >7% while, 22.1% (n = 21/95) of the patients with normal T level had HbA1c >7% (p < 0.05). There were significant associations between the number of patients with low level of total T or DHEA-S and poor control of DM. Patients with low T level were two times more likely (56.3%, n = 18/32) to have severe ED than patients with normal T level (27.4%, n = 26/95) (p < 0.01). There were significant differences between the mean levels of total T or DHEA-S and poor control of DM. No significant associations were detected between hyperinsulinaemia and the level of fasting blood sugar, duration of DM, metabolic control of DM or ED severity. Patients with low T level were three times as likely to have hyperinsulinaemia as those patients with normal T level (p < 0.05). The current study clearly demonstrated that there were significant associations between low level of total T or DHEA-S and poor control of DM.

Low testosterone and the association with type 2 diabetes

PURPOSE

The purpose of this article is to describe androgen deficiency in men, the consequences of this clinically underdiagnosed endocrine disorder, and its relationship to the metabolic syndrome and the association with type 2 diabetes. An overview of prevalence, screening, diagnosis, treatment, and monitoring of male hypogonadism is presented. Method Established guidelines were used to provide definition, diagnosis, treatment, and monitoring information for male hypogonadism. A literature review from 1990 to 2007 revealed study findings that identify the link between low testosterone in men and the development of type 2 diabetes. The following databases were used to review and analyze the current literature: CINAHL, PubMed, and MEDLINE.

RESULTS

An analysis of 26 studies was completed. The key findings in all of these studies show that there is a link between low levels of testosterone and an adverse metabolic profile (ie, obesity and insulin resistance). There is evidence that hypogonadism is associated with metabolic syndrome and type 2 diabetes in men.

CONCLUSION

Male hypogonadism is a clinical condition that affects a significant number of men in the United States and can affect up to 50% of men diagnosed with type 2 diabetes. The implications for diabetes educators are two-fold: first, there is a high prevalence of low testosterone in men with type 2 diabetes, and second, educators need to have a better understanding of this disease state to provide instructional guidance for their patients and to coordinate care with other clinicians.

Hypogonadotrophic hypogonadism in type 2 diabetes

Recent work shows a high prevalence of low testosterone and inappropriately low luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations in type 2 diabetes. This syndrome of hypogonadotrophic hypogonadism (HH) is associated with obesity in patients with type 2 diabetes. However, the duration of diabetes or HbA1c are not related to HH. Furthermore, recent data show that HH is not associated with type 1 diabetes. C-reactive protein concentrations have been shown to be elevated in patients with HH and are inversely related to plasma testosterone concentrations. This inverse relationship between plasma free testosterone and C- reactive protein concentrations in patients with type 2 diabetes suggests that inflammation may play an important role in the pathogenesis of this syndrome. This is of interest since inflammatory mechanisms may have a cardinal role in the pathogenesis of insulin resistance. It is also relevant that in the mouse, deletion of the insulin receptor in neurons leads to HH in addition to a state of systemic insulin resistance. It has also been shown that insulin facilitates the secretion of gonadotrophin releasing hormone (GnRH) from neuronal cell cultures. Thus, HH may be the result of insulin resistance at the level of the GnRH secreting neuron. Low testosterone concentrations are also related to an increase in total and regional adiposity. This review discusses these issues and attempts to make the syndrome relevant as a clinical entity. Clinical trials are required to determine whether testosterone replacement alleviates insulin resistance and inflammation. In addition, low testosterone levels are associated with an increase in cardiovascular events. Testosterone therapy may therefore, reduce cardiovascular risk. This important aspect requires further investigation.

Erectile dysfunction among men with diabetes is strongly associated with premature ejaculation and reduced libido

INTRODUCTION

Among men with diabetes, little attention has been given to premature ejaculation (PE), reduced libido, and their associations with erectile dysfunction (ED), despite the presence of physical and psychologic factors that could predispose to all three.

AIM

To estimate the prevalence and inter-associations of ED, PE, and reduced libido among diabetic men and to describe the associated clinical, socioeconomic, and lifestyle parameters.

METHODS

Cross-sectional observational study of 253 men with type 2 diabetes randomly selected from a clinic in Colombo, Sri Lanka.

MAIN OUTCOME MEASURES

Erectile function was assessed using the five-item version of the International Index of Erectile Function scale. The presence of PE, reduced libido, sociodemographic, and lifestyle data was obtained using an interviewer-administered questionnaire. Clinical data were obtained from relevant physical examination, patient records, and laboratory tests, which included glycosylated hemoglobin, serum cholesterol, serum creatinine, and electrocardiogram.

RESULTS

One hundred and eighty-five (73.1%) of the individuals had some degree of ED, while 84 (33.2%) had severe to complete ED. After excluding men with complete ED, the prevalence of PE was 68 (40.2%). The overall prevalence of reduced libido was 64 (25%). In the multivariate analysis, the strongest associations with ED were PE (odds ratio [OR] = 4.41, 95% confidence interval [CI] = 2.08-9.39) and reduced libido (OR = 4.38, CI = 1.39-13.82) followed by lower income (OR = 2.16, CI = 1.32-3.52), advancing age (OR = 2.06, CI = 1.44-2.95), and duration of diabetes (OR = 1.48, CI = 1.09-2.01). In addition, ED was univariately associated with lower educational level (P = 0.05), the presence of hypertension (P = 0.005), and no alcohol intake (P = 0.001). The only significant association of PE was the severity grade of ED. Associations of reduced libido in the multivariate analysis were ED (OR=1.61, CI = 1.23-2.70), advancing age (OR = 1.7, CI = 1.4-2.2), and absence of masturbation (OR = 3.3, CI = 1.2-8.8).

CONCLUSIONS

ED was strongly associated with PE and reduced libido. Diabetic patients presenting with one of these three conditions should be screened for the other two.

Which patients with sexual dysfunction are suitable for testosterone replacement therapy?

According to all the consensus and statements of the major societies, hypogonadism should be considered a medical problem, termed late onset hypogonadism (LOH) or testosterone deficiency syndrome (TDS), only when symptoms are present. One of the most common symptoms of LOH/TDS is sexual dysfunction (SD). The main purpose of this review is to discuss the role of testosterone (T) in men's sexual function, including epidemiology, pathophysiology, diagnostic procedures, and treatment efficacy in patients affected by erectile dysfunction (ED). The prevalence of hypogonadism in men with ED ranges from 1.7% to 35%. In ED patients, hypogonadism is often associated with reduced sexual desire and nocturnal penile erections, while association with sex-induced erection is less evident. This is because T regulates not only cyclic guanosine monophosphate (cGMP) formation, through nitric oxide synthase (NOS) stimulation, but also its catabolism, through phosphodiesterase-5 (PDE5) activity. The androgen-dependent PDE5 expression could explain the reduced effectiveness of PDE5 inhibitors (PDE5i) in the treatment of erectile dysfunction in hypogonadal patients. Accordingly, T substitution in these subjects restores responsiveness to PDE5i. Recognising hypogonadism in patients with ED is essential in order to appropriately treat the disease. However, suspecting LOH/TDS in SD patients is not an easy task. Recently published structured inventories, such as ANDROTEST, might help physicians to recognize hypogonadism and to further pursue its appropriate diagnosis and treatment.

The Role of Penile Color-Duplex Ultrasound for the Evaluation of Erectile Dysfunction

INTRODUCTION

In the era of orally active agents, dynamic penile color-duplex ultrasound (D-PCDU) is not considered a necessary first screening for all patients with erectile dysfunction (ED). Various parameters, such as peak systolic flow velocity, end diastolic velocity, resistance index, acceleration time, and degree of arterial dilatation, have been suggested for the diagnosis of vascular ED by D-PCDU.

AIM

To highlight the clinical utility and evidence-based interpretation of D-PCDU criteria.

METHODS

Extensive, unsystematic PubMed literature search reviewing relevant data on D-PCDU in the evaluation of male ED.

RESULTS

The advantage of ultrasound is the minimally invasive nature of the procedure and the ability to screen patients to identify a normal arterial response of cavernous arteries. Men with sexual dysfunctions above 55 years of age and comorbidities are more likely to have multi-organ vascular dysfunction and may necessitate further testing because erectile failure may be the first presenting symptom requiring investigation and treatment even in the absence of cardiovascular risk factors. All patients affected with Peyronie's disease and younger men with persistent ED, a history of pelvic traumas, or fractures of the penile shaft should be offered ultrasonographic penile blood flow studies before referral to surgery or more invasive vascular investigations.

CONCLUSIONS

In the near future, D-PCDU may be used in preference to patients presenting with or without vascular risk factors, particularly those not responding to first-line orally active drugs and seeking an explanation as to why these agents failed.

The association of time of day and serum testosterone concentration in a large screening population

OBJECTIVE

To assess testosterone patterns during clinical hours in a large population of men participating in a national screening programme for prostate cancer, as the effect of time of day on serum testosterone concentration is unclear and largely reported in small studies.

SUBJECTS AND METHODS

Testosterone levels were measured in 3006 men attending the national Prostate Cancer Awareness Week screening programme. Blood samples were obtained between 06.00 and 18.00 hours, whenever men presented for screening. All men completed questionnaires on age, comorbidities, height and weight. Testosterone levels were compared based on four periods, i.e. T1, 06.00-10.00 (632 men), T2, 10.00-12.00 (812), T3, 12.00-14.00 (388), and T4, 14.00-18.00 hours (1174).

RESULTS

The mean (sd, range) age of the men was 60.3 (9.9, 40-94) years and the mean (sd) testosterone level was 415.2 (190.9) ng/dL. There was no change in mean (sd) testosterone levels over T1, T2 and T3, at 444.9 (206.2), 433.5 (195.8) and 434.4 (181.2) ng/dL, respectively, but levels at T4, at 380.4 (176.4) ng/dL, were lower by approximately 13% (P < 0.05). Advancing age, diabetes and obesity were associated with lower testosterone levels. The percentage of men with biochemical hypogonadism (<300 ng/dL) did not change across all four periods.

CONCLUSIONS

Testosterone levels in older men are stable throughout the morning and early afternoon, declining only modestly thereafter. Further case-controlled studies are needed to confirm these findings.

ORIGINAL RESEARCH—ENDOCRINOLOGY: NCEP-ATPIII-Defined Metabolic Syndrome, Type 2 Diabetes Mellitus, and Prevalence of Hypogonadism in Male Patients with Sexual Dysfunction

INTRODUCTION

Type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) are characterized by insulin resistance and often associated with male hypogonadism.

AIM

To discriminate the specific contribution of T2DM and MetS to male hypogonadism.

METHODS

A consecutive series of 1,134 (mean age 52.1 +/- 13 years) male patients with sexual dysfunction was studied.

MAIN OUTCOME MEASURES

Several hormonal and biochemical parameters were studied along with ANDROTEST, a 12-item validated structured interview, specifically designed for the screening of hypogonadism (total testosterone [TT] <10.4 nmol/L or free testosterone [FT] <37 pmol/L) in a male population with sexual dysfunction.

RESULTS

Irrespective of the criteria used to define hypogonadism, MetS was associated with a significantly higher prevalence of the condition, both in subjects with and without T2DM (41% and 29% vs. 13.2% and 77.1% and 58% vs. 40.6%, respectively, for TT and FT in patients with MetS and with or without T2DM, when compared with subjects without MetS and T2DM; both P < 0.0001). Conversely, T2DM was associated with a higher prevalence of hypogonadism in subjects with MetS but not in those without MetS. Patients with MetS, with or without T2DM, also showed a higher ANDROTEST score when compared with patients without MetS. Logistic multivariate regression analysis, incorporating the five components of MetS, identified a significant association of elevated waist circumference and hypertriglyceridemia with hypogonadism both in patients, with or without T2DM.

CONCLUSIONS

Our study demonstrated that MetS, and in particular visceral adiposity (as assessed by increased waistline and hypertriglyceridemia), is specifically associated with hypogonadism in subjects consulting for sexual dysfunction.

Androgen deficiency, diabetes, and the metabolic syndrome in men

PURPOSE OF REVIEW

The burden of androgen deficiency in men with diabetes and the metabolic syndrome has become increasingly apparent in population-based studies. This article focuses on the mechanisms underlying the interdependent relationship between these conditions.

RECENT FINDINGS

Various definitions of hypogonadism, the metabolic syndrome and diabetes have been proposed and are used in the literature. Cross-sectional studies have found that between 20 and 64% of men with diabetes have hypogonadism, with higher prevalence rates found in the elderly. Hypogonadism can be a risk factor for the development of diabetes and the metabolic syndrome through various mechanisms including changes in body composition; androgen receptor polymorphisms; glucose transport; and reduced antioxidant effect. Conversely, diabetes and the metabolic syndrome can be risk factors for hypogonadism through some similar but mostly distinct mechanisms, such as increased body weight; decreased sex hormone binding globulin levels; suppression of gonadotrophin release or Leydig cell testosterone production; cytokine-mediated inhibition of testicular steroid production; and increased aromatase activity contributing to relative estrogen excess.

SUMMARY

The relationship between diabetes, the metabolic syndrome and androgen deficiency is complex. Testosterone supplementation, by either oral or intramuscular routes and through exogenous or endogenous delivery, has a promising role in this population although further clinical trials are needed.

Chronic sildenafil in men with diabetes and erectile dysfunction

Erectile dysfunction frequently represents a neurovascular complication of diabetes mellitus, and it has been calculated that almost 50% of diabetic men will have erectile dysfunction within 6 years after diagnosis. Penile endothelial and smooth muscle cell dysfunction are due to molecular pathway abnormalities (i.e., activation of PKC, increased oxidative stress and overproduction of advanced-glycosylation end products). The response rate to oral drug therapies, such as sildenafil, is lower than in most other groups. Because therapeutic alternatives (i.e., intracavernous injections with vasoactive agents) are not curative, clinical trials aimed to demonstrate rehabilitative effects with daily phosphodiesterase type-5 inhibitors are ongoing. If this approach proves successful, it will determine many advantages over the intracavernosal treatment and potentially induce sexual rehabilitation.

Testosterone Regulates RhoA/Rho-Kinase Signaling in Two Distinct Animal Models of Chemical Diabetes

INTRODUCTION

The contractile RhoA/Rho-kinase (ROCK) signaling pathway is upregulated in penile tissue in animal models of experimental diabetes and has been proposed to contribute to diabetes-related erectile dysfunction (ED).

AIM

To investigate the effect of testosterone (T) on the RhoA/ROCK signaling in diabetes.

METHODS

We used two distinct animal models of chemical diabetes (alloxan-induced in the rabbit and streptozotocin-induced in the rat) with or not T supplementation.

MAIN OUTCOME MEASURES

The effect of diabetes and T supplementation on RhoA/ROCK signaling was evaluated as responsiveness to the selective ROCK inhibitor Y-27632 either by "in vitro" contractility study (diabetic rabbit) or "in vivo" as erectile response elicited by intracavernous injections (diabetic rats). RhoA/ROCK gene and protein expression were also analyzed.

RESULTS

In both models, hypogonadism was observed, characterized by reduced T plasma level and androgen-dependent accessory glands atrophy. Diabetic animals showed a significant increase in responsiveness to increasing concentrations of Y-27632. T substitution (30 mg/kg, weekly) completely prevented hypogonadism and diabetes-induced penile hypersensitivity to Y-27632. To test whether this effect was due to a T-dependent regulation of RhoA/ROCK gene expression, we measured RhoA/ROCK mRNA. Both isoforms of ROCK (ROCK1/ROCK2) were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) in rat penile samples. We found that ROCK1 mRNA was significantly increased (P < 0.05) in penile tissues from diabetic animals and maintained at the control values by T, as also confirmed by semiquantitative RT-PCR in rabbit. Conversely, RhoA and ROCK2 mRNA expression was not influenced either by diabetic condition or by T administration. Accordingly, ROCK1 protein expression, as evaluated by Western blot and immunohistochemistry analysis, was increased in penile samples from diabetic animals and normalized by T.

CONCLUSIONS

Our data further support the hypothesis that the overexpression of RhoA/ROCK signaling contributes to diabetes-related ED. Moreover, treating hypogonadism in course of diabetes may maintain erectile function also by normalizing RhoA/ROCK pathway upregulation.

ORIGINAL RESEARCH—ENDOCRINOLOGY: A Comparison of NCEP-ATPIII and IDF Metabolic Syndrome Definitions with Relation to Metabolic Syndrome-Associated Sexual Dysfunction

INTRODUCTION

Metabolic syndrome (MetS) is a clustering of cardiovascular and metabolic risk factors, often associated with erectile dysfunction (ED) and hypogonadism. Recently, the International Diabetes Federation (IDF) proposed a substantial revision of the National Cholesterol Education Program-Third Adult Treatment Panel (NCEP-ATPIII) MetS criteria, essentially lowering the diagnostic cutoff values. Aim. To investigate the associations between these two recently proposed definitions of MetS with the relative risk of arteriogenic ED and hypogonadism in a large cohort of patients with male sexual dysfunction.

METHODS

A consecutive series of 1086 patients with sexual dysfunction (mean age 51.9 +/- 12.8 years) was studied.

MAIN OUTCOME MEASURES

Several hormonal, biochemical, and instrumental (penile Doppler ultrasound) parameters were studied, along with ANDROTEST, a 12-item validated structured interview, specifically designed for the screening hypogonadism in a sexual dysfunction population. In particular, a score >8 is predictive of low testosterone (<10.4 nmol/L) with a sensitivity and specificity of about 70%.

RESULTS

The prevalence of MetS was 32.0% and 44.7% according to NCEP-ATPIII and IDF criteria, respectively. After adjustment for confounding factors, only NCEP-ATPIII was significantly associated with dynamic prostaglandin E(1)-stimulated penile flow (Vpmax, B = -7.7 +/- 3.8; P < 0.05). Patients with MetS defined according to both criteria reported lower total and free testosterone levels, higher prevalence of hypogonadism, and higher ANDROTEST score. However, when IDF, but not NCEP-ATPIII, criteria were fulfilled, the prevalence of hypogonadism was significantly lower than that observed in patients fulfilling both criteria (15.6% vs. 34.8%, respectively; P < 0.00001). Conversely, patients fulfilling NCEP-ATPIII, but not IDF, criteria did not show a significant different prevalence of hypogonadism than those positive for both sets of criteria (30.8% vs. 34.8%; P = NS).

CONCLUSIONS

In patients with ED, NCEP-ATPIII criteria seem to be a better predictor of hypogonadism and impaired penile blood flow than IDF ones.

The role of nitric oxide in erectile dysfunction: implications for medical therapy

Erectile dysfunction is a common, multifactorial disorder that is associated with aging and a range of organic and psychogenic conditions, including hypertension, hypercholesterolemia, diabetes mellitus, cardiovascular disease, and depression. Penile erection is a complex process involving psychogenic and hormonal input, and a neurovascular nonadrenergic, noncholinergic mechanism. Nitric oxide (NO) is believed to be the main vasoactive nonadrenergic, noncholinergic neurotransmitter and chemical mediator of penile erection. Released by nerve and endothelial cells in the corpora cavernosa of the penis, NO activates soluble guanylyl cyclase, which increases 3',5'-cyclic guanosine monophosphate (cGMP) levels. Acting as a second messenger molecule, cGMP regulates the activity of calcium channels as well as intracellular contractile proteins that affect the relaxation of corpus cavernosum smooth muscle. Impaired NO bioactivity is a major pathogenic mechanism of erectile dysfunction. Treatment of erectile dysfunction often requires combinations of psychogenic and medical therapies, many of which have been only moderately successful in the past. The advent of oral phosphodiesterase type 5 (PDE-5) inhibitors, however, has greatly enhanced erectile dysfunction treatment; patients have demonstrated high tolerability and success rates for improved erectile function. The efficacy of the PDE-5 inhibitors also serves to illustrate the importance of the NO-cGMP pathway in erectile function since these agents counteract the degradation of NO-generated cGMP. Because not all patients respond to PDE-5 inhibitors, additional therapies are being investigated, such as soluble guanylyl cyclase activators and NO donors, which act on NO-independent and NO-dependent pathways, respectively.

Testosterone and ageing: what have we learned since the Institute of Medicine report and what lies ahead?

A 2003 report by the Institute of Medicine (IOM) surveyed the literature on the benefits and risks of testosterone replacement therapy in older men and identified knowledge gaps and research needs. This review summarises some key studies published since the IOM report. The possible relationship of testosterone to risk of prostate cancer remains a concern; however, no new evidence has emerged to suggest that testosterone replacement therapy increases the risk. Recent studies have demonstrated that hypogonadism in men may be more prevalent than previously thought, is strongly associated with metabolic syndrome, and may be a risk factor for type 2 diabetes and cardiovascular disease. Clinical studies have shown that testosterone replacement therapy in hypogonadal men improves metabolic syndrome indicators and cardiovascular risk factors. Maintaining testosterone concentrations in the normal range has been shown to contribute to bone health, lean muscle mass, and physical and sexual function, suggesting that testosterone replacement therapy may help to prevent frailty in older men. Based on current knowledge, testosterone replacement therapy is unlikely to pose major health risks in patients without prostate cancer and may offer substantial health benefits. Larger, longer-term randomised studies are needed to fully establish the effects of testosterone replacement therapy.

Age Related Testosterone Depletion in Patients With Erectile Dysfunction

PURPOSE

We assessed the pattern of age related testosterone depletion in patients with erectile dysfunction.

MATERIALS AND METHODS

A total of 305 patients with erectile dysfunction who had a normal testosterone level at baseline visit and who completed the study were candidates for analysis. Erectile function was assessed using the International Index of Erectile Function. Patients underwent routine laboratory investigations plus total testosterone and prolactin assessment at the baseline visit and on a yearly basis for 4 years.

RESULTS

The mean age +/- SD was significantly higher in 210 patients with decreased testosterone (55.3 +/- 7.3 years) than in 95 patients with steady testosterone (remaining within the normal range) (50.8 +/- 10.2 years). There was a significant decrease in yearly mean testosterone level throughout the study in all the age groups (determined by decades) older than 30 years. Of the study population 68.9% had decreases in testosterone levels throughout the 4 years of visits. Hypogonadism (testosterone lower than normal range) developed in 7.6% of the study population. There was a significant decrease in mean testosterone at any visit in comparison to previous visits. There were significant associations between decreased levels of testosterone and increased severity of erectile dysfunction at baseline visit, longer duration and poor metabolic control of diabetes, ischemic heart disease, hyperprolactinemia and low desire.

CONCLUSIONS

This study clearly demonstrated a decrease in testosterone level throughout the 4-year followup in patients with erectile dysfunction. Patients with decreasing testosterone were older than patients with a steady testosterone level.

Inventories for male and female sexual dysfunctions

Several illnesses can distress sexual health and disrupt sexuality, an integral part of being human. These illnesses are not different in origin from those affecting other health areas, but, because sexuality is involved, effective communication and empathy between the physician and the patient may be severely hindered by negative feelings such as anxiety and guilt. A detailed general and sexual history is, however, an essential step in evaluating patients for sexual dysfunction (SD). Finding the correct way to ask questions and to decode answers on sexual health and disease might be difficult and, in some way, embarrassing. Hence, validated and standardized sexual inventories might help physicians confront SD. These case-history tools have the advantage of being standardized, easy to administer and score, relatively unobtrusive and substantially inexpensive. This review describes the main sexual inventories hitherto described and validated in different sexual areas of health and disease, and the advantages of the two main formats available to clinicians, that is, structured interviews (SIs) and self-report questionnaires (SRQs). Both types of inventories are composed of a set of standardized, written probe questions requiring a finite number of responses, driven by an interviewer (SIs) or by the patients themselves (SRQs). SRQs allow more time and intimacy to organize and develop answers to delicate questions, as are those on sexual life. In addition, SRQs could also be very useful in quantifying disease severity and treatment outcome. On the other hand, SIs help achieve a better patient-physician relationship and reduce the risk of misunderstandings.

Testosterone Undecanoate Restores Erectile Function in a Subset of Patients with Venous Leakage: A Series of Case Reports

INTRODUCTION

Androgens are critical for maintaining penile structure and function and androgen deficiency alters the function of the corporal veno-occlusive mechanism in animal models. However, there are limited research and data supporting this association in humans.

METHODS

Case reports of hypogonadal men (N = 12) with low plasma testosterone and moderate to severe erectile dysfunction are presented. Comorbidities varied, including diabetes mellitus type I or II, metabolic syndrome with possible related hypertension, dyslipidemia, or obesity. Oral phosphodiesterase type 5 (PDE5) inhibitor therapy did not improve erectile function. Each patient underwent baseline dynamic infusion pharmacocavernosometry and cavernosography revealing various degrees of corporal veno-occlusive dysfunction. The patients underwent treatment with 1,000 mg injectable testosterone undecanoate (Nebido) on day 1, followed by another injection after 6 weeks and every 3 months thereafter. Dynamic infusion pharmacocavernosography was repeated in all 12 patients after 3 months of treatment.

RESULTS

Five of the 12 patients reported significant improvement in erectile function within 12-20 weeks of androgen treatment and are currently under follow-up. Compared with baseline pharmacocavernosography, repeat radiological studies in patients who reported improvement in erectile function did not show veins draining the corporal bodies. The patients who responded to androgens also noted improvement in sexual desire domain (International Index of Erectile Function [IIEF] scores increased from 4 +/- 0.7 to 8 +/- 0.3) and erectile function domain (IIEF scores increased from 6 +/- 2 to 24 +/- 1).

CONCLUSION

The observations made in these limited series of case reports suggest that testosterone improved erectile function in hypogonadal patients by restoring veno-occlusive function. Prospective, multi-institutional, double-blind placebo-controlled trials in hypogonadal patients are indicated.

ORIGINAL RESEARCH—ENDOCRINOLOGY: ANDROTEST © : A Structured Interview for the Screening of Hypogonadism in Patients with Sexual Dysfunction

INTRODUCTION

Detecting hypogonadism, which is important in the general population, becomes crucial in patients with sexual dysfunctions, because hypogonadism can have a causal role for them and testosterone (T) substitution represents a milestone for the therapy.

AIM

No inventories are available for the screening of hypogonadism in patients with sexual dysfunction. We wished to set up a brief structured interview providing scores useful for detecting hypogonadism defined as low total T (<10.4 nmol/L, 300 ng/dL) in a symptomatic population (sexual dysfunction).

METHODS

A minimum set of items was identified within a larger structured interview through iterative receiver-operating characteristic curve analysis, with assessment of sensitivity and specificity for hypogonadism in a sample of 215 patients.

MAIN OUTCOME MEASURES

Sensitivity and specificity were verified in a further sample of 664 patients. Correlation of test scores with prostate-specific antigen (PSA), testis volume, and others clinical and psychological parameters, was assessed for concurrent validity.

RESULTS

In the validation sample, the final 12-item version of the interview (ANDROTEST) had a sensitivity and specificity of 68% and 65%, in detecting low total T (<10.4 nmol/L) and of 71% and 65%, in the screening for low free T (<37 pmol/L). Furthermore, patients with a pathological test (i.e., score >8) showed higher prevalence of hypogonadism-related signs, such as lower testis volume and higher depressive symptoms. Finally, when only younger patients (<54 years, which represents the median age of the sample) were considered, Log10 [PSA] levels were significantly lower in those with ANDROTEST score >8.

CONCLUSION

ANDROTEST is a quick and easy-to-administer interview that provides scores for the screening of male hypogonadism in patients with sexual dysfunction.

Endothelial dysfunction in diabetic erectile dysfunction

Erectile dysfunction (ED) is highly prevalent in diabetes mellitus. Pathophysiological mechanisms underlying diabetes-associated ED are in large part due to endothelial dysfunction, which functionally refers to the inability of the endothelium to produce vasorelaxing messengers and to maintain vasodilation and vascular homeostasis. The precise mechanisms leading to endothelial dysfunction in the diabetic vasculature, including the penis, are not yet fully understood. Hyperglycemia affects endothelial nitric oxide synthase activity and nitric oxide production/bioavailability, nitric oxide-independent relaxing factors, oxidative stress, production and/or action of hormones, growth factors and/or cytokines, and generation and activity of opposing vasoconstrictors. Considering recent advances in the field of vascular biology and diabetes, the emphasis in this review is placed on the mechanisms of hyperglycemia-induced endothelial dysfunction in the pathophysiology of diabetes-associated ED.

REVIEWS: Are Androgens Critical for Penile Erections in Humans? Examining the Clinical and Preclinical Evidence

Androgens are deemed critical for penile-tissue development, growth, and maintenance of erectile function, however, their role in erection, especially in humans, remains controversial. In this review, we summarize information from clinical and animal model studies to provide a comprehensive and rational argument for the role of androgens, or lack thereof, on penile erection ability in humans. The goal of this review is to present the clinical and preclinical evidence available in the literature with regard to testosterone and erectile physiology and engage the reader in this discussion. Ultimately, each reader will have to form his or her own conclusions based on the existing evidence. In humans, androgen-deficiency manifestations are noted in clinical situations such as: (i) inadequate development of the penis; and (ii) loss of erectile function in prostate cancer and benign prostatic hyperplasia patients managed with medical or surgical castration or antiandrogen therapy. Androgen treatment causes: (i) improvement in sexual function in hypogonadal patients treated with androgen supplementation; (ii) improvement in nocturnal penile tumescence in hypogonadal patients treated with androgens; (iii) improvement in erectile function with androgen supplementation in patients who did not respond to phosphodiesterase type 5 inhibitor therapy initially; and (iv) improvement in the well-being, mood, energy, and sexual function in aging men who have testosterone deficiency treated with androgen therapy. In contrast to animals, especially rodents in which the adrenal cortex does not synthesize androgens, the human adrenal is a source of peripherally circulating androgen precursors, thus, complete androgen insufficiency may not be observed in men at a younger age. Furthermore, in light of the concept that a threshold of androgen levels exists in animals and humans below which sexual function is diminished, further contributes to the complexity of understanding androgens role in erections, especially in humans. Nevertheless, based on the preclinical and clinical data available in the literature, to date, we infer that androgens play a critical role in maintaining erectile physiology in humans.

Testosterone Restores Diabetes‐Induced Erectile Dysfunction and Sildenafil Responsiveness in Two Distinct Animal Models of Chemical Diabetes

INTRODUCTION

Hypogonadism is often associated with diabetes and both conditions represent major risk factors for erectile dysfunction (ED).

AIM

To investigate the role of hypogonadism on phosphodiesterase type 5 (PDE5) expression and sildenafil responsiveness in diabetes.

METHODS

Two different models of experimental diabetes were used: (i) alloxan-induced diabetic rabbit; and (ii) streptozotocin (STZ)-induced diabetic rat. In both experimental models, animals were separated into three groups: control, diabetic, diabetic supplemented with testosterone (T) enanthate. Rabbits were used for "in vitro" experiments. Conversely, each rats group was further subdivided: no further treatment or acute sildenafil dosing (25 mg/kg, 1 hour before "in vivo" electrical stimulation [ES]).

MAIN OUTCOME MEASURE

Erectile capacity was evaluated either by "in vitro" contractility study (alloxan-induced diabetic rabbit) and "in vivo" evaluation of erectile response elicited by ES of cavernous nerve (STZ-induced diabetic rats). Also endothelial nitric oxide synthase, neural nitric oxide synthase (nNOS), and PDE5 protein (Western blot) and mRNA (quantitative real-time reverse transcriptase polymerase chain reaction [RT-PCR]) expression were measured in rat penile samples of each group.

RESULTS

In both models, hypogonadism was observed, characterized by reduced T and atrophy of androgen-dependent accessory glands. T substitution completely reverted hypogonadism and diabetes-induced penile hyposensitivity to "in vitro" (acetylcholine, rabbit) or "in vivo" (ES, rat) relaxant stimuli, along with nNOS expression, which was reduced (P < 0.05) in STZ rats. In diabetic animals, T substitution reinstated sildenafil-induced enhancement of both "in vitro" nitric oxide donor (NCX 4040) relaxant effect (rabbit) and "in vivo" ES-induced erection (rat). PDE5 was reduced in diabetic STZ rats (P < 0.05) and normalized by T. In STZ rats, sodium nitroprusside (SNP) intracavernous injection induced a more sustained erection than in control rats, which was no further enhanced by sildenafil. T substitution normalized both hyper-responsiveness to SNP and sildenafil efficacy.

CONCLUSION

In two models of diabetes T deficiency underlies biochemical alterations leading to ED. Normalizing T in diabetes restores nNOS and PDE5, and reinstates sensitivity to relaxant stimuli and responsiveness to sildenafil.