The Relationship Of Serum Testosterone To Erectile Function In Normal Aging Men:

Testosterone and erectile function in hypogonadal men unresponsive to tadalafil: results from an open-label uncontrolled study

The study was aimed at investigating the efficacy of tadalafil (Cialis) in combination with transdermal testosterone (Testogel) for the treatment of tadalafil-refractory erectile dysfunction in hypogonadal patients. In an open-label, retrospective trial, 69 hypogonadal nonresponders to tadalafil monotherapy (mean age: 59 years, total testosterone < or =3.4 ng ml(-1)) were randomly divided into two homogeneous groups. Group I (n = 35) received Testogel (5 g containing 50 mg testosterone, daily) for 4 weeks, followed by concurrent therapy with tadalafil (20 mg, twice a week). Group II (n = 34) was assigned to treatment with Testogel (5 g containing 50 mg testosterone, daily) for a duration of 10 weeks before adjunctive therapy with tadalafil was initiated. Total testosterone levels were measured at baseline, week 4 and week 10. Sexual function was assessed employing the International Index of Erectile Function (IIEF). As an additional measure of efficacy, a questionnaire completed by the patients' partner was used. Mean testosterone levels were observed to increase from baseline to study end. Following 4 weeks of therapy, an improvement in Erectile Function (EF) from baseline was observed, which was greater in group I than in group II. The assessment after week 10 showed that EF had further increased and was quite similar now in both groups. Partners found that erectile capacity had greatly improved from baseline to study end. No adverse effects have been observed. These data suggest that combination therapy with testosterone and tadalafil is an effective means in a subset of hypogonadal patients who did not respond to tadalafil alone. We assume that testosterone-induced remodelling of penile tissue structure is one underlying reason for the observed improvement of erectile function. The results imply that this process may require a longer period of testosterone administration than 4 weeks.

Endocrine causes of erectile dysfunction

Erectile dysfunction (ED) is one of the commonest disorders of male sexual function. Penile erection depends on a complex interaction of psychological, neural, vascular and endocrine factors. Testosterone has an important role in both central and peripheral domains of this process. In this article we discuss the role of testosterone in male sexual function and endocrine causes of ED.

Normal, bound and nonbound testosterone levels in normally ageing men: results from the Massachusetts Male Ageing Study

OBJECTIVE

There is little consensus on what androgen levels are 'normal' for healthy, ageing men. Using data from the Massachusetts Male Ageing Study (MMAS), we estimated age-specific, normal androgen levels for men aged 40-79 years while accounting for health status and behavioural factors known to influence hormone levels.

DESIGN

Prospective, observational study.

PATIENTS

Community-based random sample of men aged 40-79 years: n = 1677 men studied at T1 (1987-1989), n = 1031 at T2 (1995-1997) and n = 631 at T3 (2002-2004), for a total of 3339 observations. The average number of years between the T1 and T2 interviews was 8.8 (range 7.1-10.4 years) and 6.4 (range 5.6-7.9 years) between T2 and T3.

MEASUREMENTS

Serum total testosterone (T) and sex hormone-binding globulin (SHBG) were measured on nonfasting blood samples collected within 4 h of subject's awakening. Free and bio-available T were calculated from T and SHBG using the Sodergard equation. Trained interviewers administered an in-home questionnaire of health, medication and lifestyle. Participants were considered apparently healthy if all of the following were met: (i) absence of self-reported chronic disease (diabetes, heart disease, high blood pressure, cancer, ulcer); (ii) not on prescription medication believed to affect hormone levels; (iii) body mass index (BMI) not exceeding 29 kg/m2; (iv) alcohol consumption less than or equal to six drinks/day; and (v) nonsmoking.

RESULTS

Chronic disease and high BMI significantly decreased whereas smoking tended to increase total, free and bio-available T concentrations. Apparently healthy men had significantly higher median hormone concentrations at most time points than did not apparently healthy men. Due to the opposite effects of smoking and the other components of the definition, apparently healthy men were compared to nonsmoking, apparently unhealthy men. The former group had significantly higher androgen levels (Wilcoxon rank-sum P-values ranged from 0.01 to 0.0001) for all hormones at all interviews. Ninety-five percent of apparently healthy men in their 40s, 50s, 60s and 70s would be expected to have total T in the range (2.5-97.5th percentile): 8.7-31.7, 7.5-30.4, 6.8-29.8 and 5.4-28.4 nm (251-914, 216-876, 196-859, 156-818 ng/dl), respectively.

CONCLUSIONS

Age, health and lifestyle factors impact androgen levels and should be accounted for in calculations of normal reference ranges. We propose the following age-specific thresholds, below which a man is considered to have an abnormally low total T: 8.7, 7.5, 6.8 and 5.4 nm (251, 216, 196 and 156 ng/dl) for men in their 40s, 50s, 60s and 70s, respectively. These cutoffs correspond to the 2.5th percentile in our data; thus, approximately 2.5% of men aged 40-79 years would have abnormally low T levels based on hormone levels alone.

Type V phosphodiesterase inhibitor treatments for erectile dysfunction increase testosterone levels

OBJECTIVE

Lack of sexual activity due to erectile dysfunction (ED) decreases testosterone (T) levels through a central effect on the hypothalamic-pituitary axis. In this paper we studied the effect of different type V phosphodiesterase (PDE5) inhibitor treatments for ED on the reversibility of this endocrine pattern.

DESIGN

Open-label, retrospective study.

PATIENTS

Seventy-four consecutive patients were treated on demand with sildenafil (Sild) (50 mg) and tadalafil (Tad) 20 mg.

MEASUREMENTS

The success in sexual intercourse was recorded and total (tT) and free testosterone (fT) levels were studied before and after 3 months of treatment.

RESULTS

Basal level of tT and fT were at the bottom of the normal range and LH levels were at the top of the high normal range. After treatments, this endocrine pattern was reversed in both groups. However, the T increase in Sild-treated patients was significantly lower than in those treated with Tad (4.7 +/- 2.7 vs. 5.1 +/- 0.9, P < 0.001). fT levels followed a directly proportional pattern, while the inverse was found when LH production was studied. The intercourse rate reflected this effect: in fact, the Sild group showed a 4.9 +/- 2.9/month full sexual intercourse rate while in the Tad group a significantly higher rate of sexual intercourse was found (6.9 +/- 4.6/month, P = 0.04). However, drug consumption was comparable between the groups (Sild 4.9 +/- 2.9 vs. Tad 4.4 +/- 2.8 pills/month, P = 0.72).

CONCLUSIONS

As it is unlikely that the two drugs have a different direct effect on the pituitary-testis axis, this effect is probably due to the higher frequency of full sexual intercourse in the Tad-treated group, because of the drug's longer half-life.