Cause of low testosterone level – What is causing your testosterone levels to plummet

You may have heard about declining testosterone levels in men during the recent decades or maybe you stumbled upon here after finding out you have low testosterone levels yourself. The fact is that the average amount of testosterone in males all around the world has been on the decline for quite some time. Once you understand the mechanisms behind this decline it makes perfect sense. But before we go ahead with the cause of low testosterone level, let’s recap what testosterone is, what it does and why it’s so freaking important for men specifically.

What is testosterone 

Testosterone is the prime male hormone that is produced mainly in the testicles but also in the adrenal cortex and the ovaries in females. While testosterone is usually thought of as the hormone responsible for the secondary sexual male characteristics like deeper voice, facial hair and increased muscle mass it has other important roles in the human body and is very important for females too. Naturally males have far higher amounts of testosterone since testicles are the main gland responsible for testosterone production and this is the reason men mostly look like men and women like women.

Physiologically testosterone belongs to a group of hormones called androgens (meaning male hormones). The other two hormones in this group being dihydrotestosterone (DHT) and androstenedione. More about them later. Testosterone is also an anabolic steroid – a substance that is capable of increasing muscle mass substantially.

What does testosterone do 

Testosterone has several important functions in the human body. As I mentioned earlier it’s responsible for the secondary male characteristics but it also has a multitude of metabolic and even psychological functions. Not only does testosterone affect fat metabolism, bone density and muscle mass but it also has somewhat significant behavioral effects.

Testosterone and it’s metabolite DHT increase male sex drive and libido, competitive drive and general well being. It also lowers the level of perceived stress yet testosterone levels are easily disturbed by stress reactions and hormones like cortisol and adrenaline. The common myth is that testosterone increases aggression and makes men violent. This is simply not true and quite the opposite effect is observed in males with high normal testosterone levels. Testosterone has actually been shown to increase positive social interaction among men and low testosterone levels are associated with feelings of depression, anxiety, irritability, anger and social withdrawal. It is true that abnormally high testosterone levels such as can be found on steroid abusers  can cause aggressive, unpredictable and violent behavior. However the levels in such cases are 10, 100 even 1000 fold what can be naturally achieved.  It is also true that prisoners convicted for violent crimes have usually higher than above testosterone levels. But they also have many other traits that make them prone to act violently and correlation with high testosterone levels and violent behavior has not been shown to be true in the general population.

How does it work

The production of testosterone starts from the brain in the HPTA, short for Hypothalamic Pituitary Gonadal -axis. When the hypothalamus senses a need for increase in testosterone levels (mainly by estrogen and progesterone levels) it releases a hormone called gonadotropin-releasing hormone or GnRH which tells the pituitary to release two hormones, luteinizing hormone and follicle stimulating hormone.  These hormones are then carried to the testis by the bloodstream and sensed by receptors in the gonads which start to produce sperm and secrete testosterone.

Once testosterone hits the blood stream it’s carried  to tissues all over the body. The tissues that testosterone has effects on have special receptors (androgen receptor) for the testosterone molecules to bind to. In some tissues (mainly prostate, liver and the brain) testosterone is converted into DHT by a certain enzyme. DHT is considerably more potent agonist for the androgen receptor testosterone. So in some cell types testosterone interacts directly with the androgen receptor while on others it’s first converted to DHT by alpha reductase enzyme before interacting with the receptor. Once testosterone or DHT binds to the cells androgen receptors it affects gene expression within the cells DNA causing the androgen effect.

Another important way testosterone has effects is by conversion to estrogen and estradiol, the main female hormones. Many tissues in the human body secrete an enzyme called aromatase, which converts testosterone in to estrogen. One of the main sources of aromatase is body fat. Estrogen is an important hormone that has many functions also in males. However when estrogen levels are high it tends to effect the HPA axis which lowers testosterone production and can also have feminizing effects like breast growth.

The cause of low testosterone

So now that you have the basic knowledge of testosterone I can tell what  I have found through my research and own experience to be the cause low testosterone level in modern man. There are five main causes that I have found to be responsible for low testosterone:

1. Stress
2. Diet
3. Obesity
4. Lack of sleep
5. Micronutrient deficiency

Mainly in order of importance but there is individual variability of course.

That’s it for today. I will soon write part 2 to this post, where I will open up the causes a bit and tell what you can do about them.