What Is Testosterone

You’re on a recent long drive listening to a podcast a friend sent you, while everyone else in the car is asleep. The guest is talking about testosterone. Low testosterone, high testosterone, men on it, women on it and everything in between. The longer you listen the more you see yourself in the symptoms they’re talking about. You previously associated testosterone with ripped athletes at the gym, body builders, aggression, and amped up sex drive but now you’re learning about the nuance and your previous notions are out the window.

We’ve heard a similar story to the one above countless times and when clients come in to discuss how they’re feeling or have concern for low testosterone, we like to start with information and science.

Over the next 4 blog posts, we will focus on testosterone. We’ll explore what testosterone is, how low levels manifest, what TRT is and risks/benefits of TRT. In this first posts about testosterone, we’ll start with the fundamentals. If there were a Schoolhouse Rock video about testosterone production, rest assured we would have posted it instead.

OVERVIEW

Testosterone is a steroid hormone in a class called androgens. It plays a pivotal role in the development and maintenance of male reproductive tissue like the prostate and testicles, and how male secondary characteristsics like facial hair, Adam’s apple development, bone structure, body shape, and body hair manifest. Testosterone impacts mood, brain function, metabolism, energy output, bone density and even social interactions. Women also make testosterone and it plays a role in simlar functions mentioned above, but male levels are roughly 8 times higher. Testosterone naturally decreases as we age and comorbid disease such as diabetes and even obesity can prematurely lower testosterone levels.

THE BRAIN

Testosterone might be produced in the testes, but the process starts in the brain. Testosterone production is regulated by two structures in the brain: the hypothalmus and the pituitary gland. These two structures secrete hormones that tell receptors in the testes to produce testosterone. Together, this pathway is called the Hypothalmus-Pituitary-Gonadal Axis, or the HPG axis. This axis works like a game of telephone and though we hope the message stays consistent through the system, sometimes, just like in the game of telephone, we enounter a glitch and the message comes through inaccurately. When this happens, we see symptoms that clue medical providers to a problem that needs addressing. When we check testosterone levels at Vitality, we not only assess how the testes are producing testosterone, but also how strong the brain signaling is, so get a better idea how each person’s body is functioning.

CREATION & TRANSPORT

Testosterone is produced by cells in the testes called Leydig cells. In these cells, cholesterol is converted into testosterone by a complex series of enzyme reactions. Testosterone is then released into the bloodstream. Testosterone in the blood stream is bound to proteins called sex hormone binding globulin (SHBG) and albumin. Only a small fraction of testosterone is free, or biologically active for the body to use. SHBG is something we check in a testosterone panel to find out how much of your testosterone is avaible to use and how much is present but not really usable. Once in the bloodstream, testosterone is free to find a receptor and unlock the potential.

RECEPTORS

Think of testosterone and receptors like a lock and key mechanism. Testosterone is the key that fits in receptors all around the body. Once the key finds an available lock, the lock and key complex can enter a cell’s nucleus and influence gene expression. Think of it like a door that opens to a surprise party. Until the key fits in the lock that opens the door, it’s quiet and nothing is happening. But once the door is unlocked, people jump up and scream and yell and throw confetti at you. Young men typically have lots of testosterone which allows a flood of receptors to always be available for the full effets of testosterone in the body. However, if there is not enough testosterone in the body, locks go unopened and the potential is inaccessable. As men age, less testosterone is available which means less keys to open the locks. Those locks access hormone receptors to help brain clarity, building muscle, sustaining endurance, motivation and sex drive. No testosterone key = no receptor locks open = low motivation, less muscle mass, low sex drive and brain fog. Some literature draws similarities to menopause and even call this andropause. Less active hormone to turn on the receptors leads to a host of downstream issues that make our bodies feel foreign to us.

EXPRESSION

As mentioned above, tesosterone is the key that unlocks the receptors. Those receptors do things like create sperm in the testes, maintain bone and muscle mass, promote protein synthesis, influence fat metabolism and fat distribution as well as overall body composition. Testosterone receptors regulate libido or sex drive, sexual arousal and maintenance of erectile function. Testosterone is a potent hormone with a wide variety of impact in both male and female bodies. In our next post in this series, we will discuss testosterone hormone level ranges and symptoms that can be experienced at various levels.

Our hope in this first post about testosterone is to provide a 10,000’ overview on the fundamentals of the androgen hormone, tesosterone. Please check out our glossary post for more terms and definitions. Education is fundamental to our mission at Vitality and we welcome your questions in person, to our email or DM on social media. We want to help you make informed decisions about your body, and understanding how things work and why we make recommendations we do is paramount to our practice.