With normal aging, there is a decrease in production of testosterone by the testes. It is thought that this decline in testosterone is the single most important cause of andropause. Approximately 30% of men 60-70 years of age and 70% of men 70-80 years of age have low bioavailable or free testosterone levels. The first step in testosterone production begins in the area of the brain called the hypothalamus. Two hormones which are secreted by the hypothalamus, namely FSH and LH, signal the testes to produce both sperm and testosterone, respectively. While it is estimated that a man is born with over 700 million Leydig cells (the cell responsible for making testosterone) in the testes, he loses six million of these cells yearly after the age of 20. After testosterone is made by the Leydig cells in the testes, it is released into the bloodstream where it has many different fates. Some testosterone attaches to sex hormone binding globulin (SHBG) which helps to bind up excess testosterone and estrogen that are floating in the bloodstream. Additionally testosterone may be converted into other hormones via 2 distinct enzymatic pathways. In one pathway, testosterone is converted into dihydrotestosterone (DHT) through the action of 5-alpha reductase which has been found to be in especially high concentrations in the prostate gland. In another pathway, testosterone is converted directly into estrogen by the enzyme aromatase, which has been found to be in high concentrations in skin, fat, bone and brain cells.
Free testosterone, otherwise known as bioavailable testosterone, is the amount of testosterone that is not bound to SHBG or that is converted into other hormones. It is this free testosterone that is the small fraction of useable testosterone that has metabolic activity and therapeutic value within the cells. In andropause, the amount of free testosterone declines and the amount of SHBG actually increases. Thus, free testosterone becomes increasingly bound to this protein making already dwindling supplies of testosterone less effective.
Just as free testosterone levels are declining, levels of the enzyme aromatase tend to increase with age. Aromatase is found in high concentrations in fat cells, especially in the abdominal region, and converts testosterone into estrogen, further depleting testosterone stores and increasing estrogen levels. This can potentially lead to adverse effects seen with increasing estrogen levels, such as prostate enlargement and increased risk for prostate cancer.
Additionally, more free testosterone may be converted into DHT by the enzyme 5-alpha reductase in the prostate gland. DHT is the most potent form of testosterone, and stimulates the synthesis of specific proteins and causes new prostate cells to proliferate. The most widely accepted theory by conventional medical doctors regarding DHT suggests that DHT is the primary cause of abnormal cell growth in the prostate, leading to Benign Prostatic Hyperplasia (BPH) and cancer of the prostate.
However, this theory has been widely scrutinized and it is now believed that the growing imbalance between estrogen and testosterone levels in aging men also plays a substantial role in the development of BPH. It is known, however, that DHT plays a significant role in hair building and growth in men. DHT is produced directly in the skin and is highest in concentration on the head. In normal amounts, DHT helps to produce and maintain healthy amounts of hair on top of the head. However, excess DHT can lead to male pattern baldness commonly seen in aging men.
The adrenal glands are two glands that sit atop each kidney and are responsible for secreting hormones that control blood pressure, blood sugar regulation, and hormones of reproduction, including testosterone. If a person is under significant amounts of stress over a long period of time (weeks to years), this can lead to potential difficulties in the adrenal glands’ ability to produce enough hormones.
This can affect people in a variety of ways and can mimic or exacerbate the effects of andropause. For instance, such symptoms of both adrenal fatigue and andropause are fatigue, anxiety, depression, and weight gain. Adrenal function can be tested and hormonal balance can be restored through nutritional and synthetic supplementation.
Hypothyroidism is another condition that may mimic or actually exacerbate the effects of andropause. Your thyroid gland is located in the front of the neck and is responsible for secreting thyroid hormone which plays a role in maintaining body temperature, energy metabolism, weight control and heart function. Those with hypothyroidism can feel sluggish, fatigued and gain weight more easily, like as is seen in andropause. It is therefore important to have thyroid function tested to determine if it is a thyroid imbalance leading to certain symptoms or actually andropause.
Environmental Causes of Andropause
As was discussed previously, declining testosterone levels and increasing estrogen both play an important role in the developing symptoms seen in andropause. There are certain compounds in the environment that men might not realize that they are ingesting, breathing and rubbing on their skin each day that might be contributing to or exacerbating their symptoms of andropause. These compounds can include plasticizers, organochlorides, bromated fire retardants (applied to prevent electronics, clothes and furniture from igniting), sunscreens, and heavy metals.
Environmental estrogens, known as “xenoestrogens,” arise as artifacts during manufacturing of plastics and other synthetic materials. Others are metabolites generated from pesticides or steroid hormones used to stimulate growth of livestock. Many of these estrogens, foreign to the human body, mimic the estrogen that men have in their body and by binding to the same receptors throughout the body, wreak havoc on reproductive function. This may lead to the decreasing testosterone levels seen in andropausal men or making the amount of free testosterone that men do have substantially weaker.
Bisphenol A (BPA) is a specific industrial chemical “xenoestrogen” that is found in the manufacture of food cans, milk containers, food storage containers and water supply pipes. Recent research in Cancer Research showed that BPA can potentially encourage the growth of a specific type of prostate cancer cell thus leading to prostate cancer itself or cause mutations and lead to the progression or aggressiveness of existing prostate cancer.A study by the Lancet published in 1993 found that there was a correlation between decreasing sperm counts in the United States and 20 other foreign countries with the increasing amount of xenoestrogens found in the environment. In addition, the rate of testicular cancer, usually only affecting young men in their 20s and 30s has increased worldwide over the last 3 decades.