The androgen receptor CAG repeat polymorphism

Sexual desire in female-to-male transsexual persons: exploration of the role of testosterone administration

OBJECTIVE

To describe sexual desire in female-to-male transsexual persons post sex reassignment surgery (SRS). The associations between serum androgen levels and sexual desire are examined.

DESIGN

Single center cross-sectional study.

METHODS

Forty-five female-to-male transsexual persons post SRS completed a standardized questionnaire assessing sexual desire (Sexual Desire Inventory). In addition, participants were asked questions on sexual desire before starting hormone treatment and having SRS. Serum levels of testosterone, LH and sex hormone-binding globulin were measured on fasting morning serum samples.

RESULTS

In retrospect, 73.9% of the participants reported an increase in sexual desire after hormone treatment and SRS. Solitary sexual desire scores were significantly correlated with frequency of masturbation (r=0.835; P<0.001), whereas frequency of sexual intercourse with a partner was not. No direct associations were found between testosterone and solitary or dyadic sexual desire. However, ANOVA showed an independent effect of LH on solitary sexual desire (P<0.001). Post hoc analysis revealed that female-to-male transsexual persons with elevated levels of LH, indicating suboptimal testosterone therapy, reported significantly lower solitary sexual desire levels (than those with low LH levels; P=0.007). Suppressed LH levels were also associated with having a higher need for sexual activities (P=0.009) and a higher frequency of excessive sexual desire (P=0.007).

CONCLUSION

Most female-to-male transsexual persons report on a marked increase in sexual desire after testosterone treatment and SRS. No direct associations between levels of testosterone and solitary or dyadic sexual desire were found. However, measures of sexual desire were inversely associated with LH levels.

Genetics of obesity and overgrowth syndromes

Childhood overweight and obesity is highly prevalent within society. In the majority of individuals, weight gain is the result of exposure to an 'obesogenic' environment, superimposed on a background of genetic susceptibility brought about by evolutionary adaptation. These individuals tend to be tall in childhood with a normal final adult height, as opposed to those who have an underlying monogenic cause where short stature is more common (although not universal). Identifying genetic causes of weight gain, or tall stature and overgrowth, within this setting can be extremely problematic and yet it is imperative that clinicians remain alert, as identification of a genetic diagnosis has major implications for the individual, family and potential offspring. Alongside this, the recognition of new genetic mutations in this area is furthering our knowledge on the important mechanisms that regulate childhood growth and body composition. This review describes the genetic syndromes associated with obesity and overgrowth.

Testosterone and type 2 diabetes

PURPOSE OF REVIEW

To describe the relationship between testosterone levels and type 2 diabetes (T2D).

RECENT FINDINGS

Multiple epidemiological studies have shown that low testosterone levels are associated with and predict the future development of T2D and the metabolic syndrome. Although this relationship is confounded by the association of total testosterone with sex hormone-binding globulin, free testosterone remains associated with measures of insulin resistance and T2D in some, but not all studies. Although the link between low testosterone levels and insulin resistance is not solely a consequence of adiposity, current studies suggest that a substantial component is mediated through its association with body fat, in particular abdominal visceral adipose tissue. This testosterone-fat relationship is bi-directional, as both weight loss and testosterone therapy increase testosterone levels, reduce fat mass, and decrease insulin resistance.

SUMMARY

Low testosterone levels are very commonly found in men with T2D and are associated with aging and obesity. Whether testosterone treatment in men with T2D decreases insulin resistance above that attributable to its fat-reducing effect is currently unknown. Future studies should compare testosterone treatment with lifestyle changes (exercise and weight loss measures), and other insulin-sensitizing agents. Until further evidence is available, testosterone therapy outside clinical trials should be reserved for diabetic men with unequivocal hypogonadism.

Prevalence of symptomatic androgen deficiency in men

CONTEXT

Despite recognition that androgen deficiency in men should be defined according to biochemical and clinical criteria, most prevalence estimates are based on low testosterone levels alone.

OBJECTIVE

The objective of this study was to examine the association between symptoms of androgen deficiency and low total and calculated free testosterone levels and estimate the prevalence of symptomatic androgen deficiency in men.

DESIGN

This study was a population-based, observational survey.

PARTICIPANTS

A total of 1,475 Black, Hispanic, and white men, between the ages of 30-79 yr, with complete data on testosterone, SHBG, and symptoms of androgen deficiency, and who are not taking medications that impact sex steroid levels were randomly selected from the Boston Area Community Health Survey.

OUTCOME

Outcomes were measured as symptomatic androgen deficiency, defined as low total (<300 ng/dl) and free (<5 ng/dl) testosterone plus presence of low libido, erectile dysfunction, osteoporosis or fracture, or two or more of following symptoms: sleep disturbance, depressed mood, lethargy, or diminished physical performance.

RESULTS

Mean age of the sample was 47.3 +/- 12.5 yr. Approximately 24% of subjects had total testosterone less than 300 ng/dl, and 11% of subjects had free testosterone less than 5 ng/dl. Prevalence of symptoms were as follows: low libido (12%), erectile dysfunction (16%), osteoporosis/fracture (1%), and two or more of the nonspecific symptoms (20%). Low testosterone levels were associated with symptoms, but many men with low testosterone levels were asymptomatic (e.g. in men 50+ yr, 47.6%). Crude prevalence of symptomatic androgen deficiency was 5.6% (95% confidence interval: 3.6%, 8.6%), and was not significantly related to race and ethnic group. Prevalence was low in men less than 70 yr (3.1-7.0%) and increased markedly with age to 18.4% among 70 yr olds. Projection of these estimates to the year 2025 suggests that there will be as many as 6.5 million American men ages 30-79 yr with symptomatic androgen deficiency, an increase of 38% from 2000 population estimates.

CONCLUSIONS

Prevalence of symptomatic androgen deficiency in men 30 and 79 yr of age is 5.6% and increases substantially with age. The aging of the U.S. male population will cause a large increase in the burden of symptomatic androgen deficiency. Future work should address the clinical significance of low testosterone levels in asymptomatic men.

[LOH (late-onset hypogonadism) or the "aging male"]

Due to lacking evidence of the data about testosterone deficiency of the aging male or LOH (late-onset hypogonadism), this subject is still a challenge for urologists, endocrinologists, and dermatologists or andrologists. This challenge faces basic research as well as clinical investigations. We have to accept responsibility for solving this challenge to better understand and better treat our patients beyond the scope of current guidelines.