Testosterone

Follow-up Investigation

O'Carroll's survey uncovered only one study describing the therapeutic use of a hormone alone. This investigation involved a double-blind crossover comparison of T and placebo in a group of men with normal circulating T levels (59). Ten men complained principally of loss of sexual interest and 10 men complained of erectile failure. The authors found a significant increase in sexual interest produced by T in the first group but qualified this by saying that in only 3/10 of the subjects was it considered to be an "adequate form of treatment," and in the others, "the changes were either small or did not generalize to the sexual relationship." O'Carroll concluded his review by saying that T "may have a modest role to play in the treatment of some men who present with low sexual interest..." but he also cautioned others in the interpretation of the data to remember that this study involved a group of only 10 men (50).

T is weakly soluble in water and is therefore poorly absorbed. In addition, T is rapidly metabolized in the liver. For both reasons, there is limited bioavailability via the oral route and so other methods of delivery have been developed: injections and transdermal (patch, and gel). An exception to comments about oral delivery is testosterone undecanoate (available in Europe and Canada at the time this is written) which is absorbed via the lymphatic system and is therefore only partially inactivated in the liver.

Testosterone enanthate and testosterone cyprionate can be given by injection, usually 150-200 mg given every 2-3 weeks (amount and frequency depends on blood level monitoring).

Patches deliver 4-6 mg/day. Scrotal skin (shaved) is highly permeable but concerns have developed over high levels of DHT and therefore nonscrotal patches have been developed. Gel formulations are applied to nongenital skin. Transdermal methods are advantageous in that one could immediately stop the drug if that seems desirable.

Age-Related Hypogonadal Syndrome (Andropause/ADAM/PADAM)

Not only has the validity of an age-related hypogonadal syndrome in men provoked controversy, but it has also raised the issue of whether or not it should be treated with T. In 2002, the National Institute on Aging and the National Cancer Institute asked the Institute of Medicine (IOM) to conduct an independent assessment of the potential benefits and adverse health effects of testosterone therapy in older men and to offer recommendations. The result was the report entitled: "Testosterone and Aging" (21).

Treatment with T is approved for the care of clearly established male hypogonadism—at any age. However, there have been few studies (especially randomized, double-blind, and placebo-controlled) on the use of T in healthy middle-aged or older men who may have a T level in the low range of a young adult but may also have one or more symptoms that are common both to hypogonadism and aging. The IOM report summarized their review of studies on the use of T in older men by cautioning that although finding 31 placebo-controlled trials, the largest sample size involved 108 subjects, the duration of treatment in 25 of the trials was 6 months or less, and only one lasted more than 1 year. In what might be interpreted as understatement, the report concluded that "... assessments of risks and benefits have been limited, and uncertainties remain about the value of this therapy for older men" (21; pp. 1-2).

One can do little better than quote from some the comments and judgements in the IOM report: "Viewed by some as an anti-aging tonic, the growth in testosterone's reputation and increased use by men of all ages in the United States has outpaced the scientific evidence about its potential benefits and risks" (p. 11). "Experience with the use of postmenopausal hormone therapy in women and the growing body of scientific evidence about its risks and potential benefits provides an apt and timely example of the need for sustained analysis of short- and long-term effects of new treatments and the caution that must be exercised in widely prescribing drugs as preventive measures. In the meantime, clinicians are searching for therapies, and an enthusiastic and perhaps overly optimistic citizenry is eager to not only treat diseases associated with aging but also possibly delay the timing of their initial onset" (p. 163).

Testosterone Replacement Therapy (TRT): General and Adverse Effects (24)

Sexual: (a) In hypogonadal men: Primary effect appears to be central and on sexual desire (mediated by markedly increased fantasy), rather than peripheral on the genitalia; sleep-related erections are androgen-dependent as is the rigidity of those erections; androgens have no effect on visual erotic stimuli. (b) On eugonadal men: "It is assumed that (normal) men have plasma androgens at concentrations substantially higher than the threshold levels required for behavioral activation"; desire increased without change in sexual behavior (60).

Prostate: Increase in prostate size and in prostate-specific antigen (PSA), but the prostate remains within normal size for eugonadal men and the PSA within normal levels. "The possibility cannot be excluded that promotion of precursor lesions is stimulated by androgens; therefore, androgen substitution should not lead no [sic] superphysiological [sic] plasma levels of androgenic steroids." This warning must make clinicians especially vigilant in view of the fact that incidental prostate cancer is found in 10% of men undergoing surgery for an enlarged prostate. Some believe that a biopsy should be done before initiation of hormonal treatment.

Hematopoiesis: Stimulation of renal production of erythropoietin (by both T and DHT); evidence for a direct effect of androgens on erythropoietic stem cells; androgen receptors have been found in cultured erythroblasts. However, treatment with T does not always lead to problems with polycythemia.

Sleep apnea: Exacerbation of pre-existing sleep apnea; special attention should be given to men who are overweight, heavy smokers, or who have chronic obstructive lung disease.

Gynecomastia: Especially in men with liver or kidney disease.

Body composition: Decrease in body fat; increase in lean body mass; and change in some aspects of muscle strength.

Bone: Increase in bone density and slowing of bone turnover.

Mood and cognition: Improvement in spatial cognition; improvement in sense of well-being.

Body fluid and glucose metabolism: Fluid retention (resulting in worsening hypertension); peripheral edema; congestive heart failure; decrease in fasting blood glucose; decrease in insulin resistance.

Skin: Change in regulation of sebaceous glands and hair growth. Hyperprolactinemia

Depending on the cause, hyperprolactinemia can be treated medically or surgically.

When the etiology is a prolactin-secreting tumor of the pituitary gland (pro-lactinoma), then surgery becomes an option. The sooner such a diagnosis is made the better since 40% of patients already have visual field defects at the time of presentation.

Most commonly, hyperprolactinemia is treated medically by using dopa-mine D2 agonists such as bromocriptine initiated at 2.5 mg/day and titrated up to 25 mg/day, or cabergoline, a longer acting dopamine agonist, starting at 2.5 mg twice a week and increasing to 0.5 mg twice/week (22; p. 34-35). As psychosis is a side effect of bromocriptine it should be used with caution.

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