Testosterone is responsible for normal growth and development of male sex organs and maintenance of secondary sex characteristics. It is the primary androgenic hormone.
When the testes fail to produce normal levels of testosterone, testosterone deficiency results. Hypogonadism is caused by primary testicular failure. Testosterone levels are low and pituitary gonadotropins are elevated. In hypogonadism, there is inadequate secretion of pituitary gonadotropins. In addition to a low testosterone level, LH and FSH levels are low or low-normal. The development of hypogonadism after puberty frequently results in complaints such as diminished libido, erectile dysfunction, infertility, gynecomastia, changes in body composition, reductions in body and facial hair, and osteoporosis. Hypogonadal men report higher levels of anger, confusion and depression.
There are now a variety of products available to treat testosterone deficiency. Successful management of testosterone replacement therapy requires appropriate evaluation and an understanding of the benefits and risks of treatment.
Proper Diagnosis of Testosterone Deficiency
There are many causes of testosterone deficiency. A medical history, physical exam, and the proper laboratory evaluations are imperative. The medical history should include questions regarding abnormalities at birth, the current status of sexual function and secondary sexual characteristics, such as beard growth, muscular strength, and energy level. Hypogonadal men have statistically significant reductions in the incidence of nocturnal erections, the degree of penile rigidity during erection, and the frequency of sexual thoughts, feelings of desire, and sexual fantasies. Furthermore, alterations in body composition, changes in adipose tissue, increases in percentage of body fat and reduction in muscle mass are frequently seen in hypogonadal men.
Proper labs should be drawn to determine a diagnosis. The following levels should be drawn in the morning: FSH, LH, SHBG, Total and Free Testosterone, Estradiol and Estrone.
Clinical rational for Testosterone Replacement Therapy
Testosterone replacement should, in theory, approximate the natural, endogenous production of the hormone. The average male produces 4-7 mg of testosterone per day in a circadian pattern, with maximal plasma levels attained in early morning and minimal levels in the evening.
The clinical rationale for treatment of testosterone deficiency may include:
- Increasing bone density
- Enhancing body composition by increasing muscle strength and reducing adipose tissue
- Improving energy and mood
- Improving libido and erectile function