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Andropause
Michael Lam, MD, MPH
www.DrLam.com
(READING TIPS: For
fast reading, scan through the topic headings in BOLD BLACK, important conclusions
in BOLD BLUE, and " Must Know " in BOLD RED. To jump to specific sections in this article, click on the
respective LINKS
in the Contents.)
Contents
Introduction
Male Reproductive System
Symptoms of Andropause
Reproductive Capacity
Mechanism of Andropause
Other Hormone Deficiencies
Andropause Treatment
1. Testosterone Replacement Therapy
(TRT)
2. Growth Hormone (hGH)
3. DHEA
4. Pregnenolone
5. Melatonin
6. Normalization of Hypothalamic
Function
7. Other Male Reproductive Enhancers
8. Prostate Protection
9. Nutritional Supports
10. Diet
Summary
 Introduction
"Midlife crisis" -- this is often the transitional period for men
when they experience what is termed as the “second childhood”.
This period usually starts from age 40 to 45. It is also called andropause or
male menopause because its symptoms coincide with the decrease in a class of
male hormones called androgen. All men are affected, although some
to a larger degree than others. A thorough knowledge of the underlying hormonal
and physiological changes will better prepare all males to deal with this phase
of life.
Male Reproductive System
The male reproductive regulatory system consists of four components:
- the central nervous system (CNS) including the hypothalamus
- the pituitary gland
- the testes; and
- the end organs where testicular steroids act.
The master control starts in the hypothalamus where gonadotropin-releasing
hormone (GnRH) is synthesized and is released in a pulsatile fashion into a
vascular network that connects the hypothalamus to the pituitary gland. GnRH
production and release is controlled by numerous neurotransmitters, including
norepinephrine, dopamine, and endorphins. GnRH regulates the release of two
pituitary hormones - the gonadotropins - luteinizing hormone (LH) and follicle-stimulating
hormone (FSH) in a pulsitile fashion. LH regulates the production and secretion
of testosterone by the Leydig cells of the testes, and FSH stimulates spermatogenesis.
Testosterone circulates in the blood in several forms. It can be bound to
both albumin and sex hormone-binding globulin (SHBG) where it is referred to
as "bound testosterone." This is the least active form. It can also
circulate in a free (unbound) form, which is considered the most active.
Testosterone can exert its effects directly on the testosterone receptors in
cells. It can also be converted to two active metabolites - dihydrotestosterone
(DHT) through the enzyme 5 alpha reductase, or by the enzyme aromatase to estradiol.
Symptoms of Andropause
Testosterone, together with its metabolites, is collectively
known as androgens. As a group of steroid hormones, they stimulate the development
of masculine characteristics and are responsible for male puberty characterized
by deepening voice, broadening shoulders, and moustache growth.
The hallmark of andropause is declining testosterone levels.
Testosterone levels begin to
decline with age after maturation. This is accompanied by the concurrent appearance
of a myriad of related physiological changes commonly associated with aging.
These changes include diminished libido, reduced frequency of sex (the "senior
slump"), erectile dysfunction, infertility, changes in body composition,
reductions in body and facial hair, and osteoporosis. Andropause is in effect
the reverse of puberty.
In addition, mood inventory scores indicate that during andropause, men report
levels of anger, confusion,
depression, and fatigue that are significantly higher than those reported by
men with normal testosterone levels. The average human male begins
to feel some symptoms of andropause after 40 to 45 years old, which is followed
by rapid deterioration after the age of 50.
Many of the symptoms accompanying the andropause and the aging processes in
men are similar to those of hypogonadism. We can attribute at least some of
these symptoms to a decrease in testosterone levels, including:
- Sexual Functions. Coital frequency declines rapidly with age from a mean maximal coital
frequency of about 4 times per week at age 25, to once a week at age 50, 3
times a month at age 70, and 1.7 times a month between the ages of 75 and
79 years. Impotence also increases dramatically with age. It is rare
before the age of 30. It is observed in 8 percent of people over 50 years
old, 20 percent of those over 65 years old, close to 40 percent for those
who are 70 years old.
- Body Composition. The amount
of lean body mass in the sedentary person decreases by approximately 10 percent
for every decade after the age of 30. You could have lost 30-40 percent of
your lean body mass by age 60. Aging is accompanied by a decrease in lean
body mass (LBM) and a concurrent significant increase in fat mass. Although
aging itself is an important determinant of body composition, plasma total
testosterone levels are not correlated to fat mass, regardless of age. The
decrease of muscle mass is highly correlated to free testosterone levels,
which persists after correction for age. Testosterone supplementation increases
muscle mass.
Aging males, like hypogonadal men, accumulate preferentially visceral fat.
This accumulation is a major cause of insulin resistance and the atherogenic
lipid profile. This suggests that obesity in elderly men is a more important
health hazard than in young men. Contrary to popular belief, clinical trials
have shown that a low androgen status increases the risk of coronary artery
disease (CAD) or atherosclerosis. It was previously believed that testosterone
and other androgens had the opposite effect since men have higher rates of heart
disease generally than women. Researchers now find that low androgen levels
were associated with an increased incidence of CAD. Men with CAD had a 22 percent
lower 'free androgen index'.
While decreased free and total testosterone levels can lead to increased fat
mass, it could also be suggested that the decrease in testosterone levels in
the aging male is the consequence of an increase in fat mass. In other words,
there is a likely bi-directional relationship, the exact mechanism of which
is still not fully known. Obesity is a multi-factorial disease that also includes
genetic, social and psychological factors.
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