What is Low Testosterone?
Medically reviewed by Dr. Larry Lipshultz M.D
If you listen to the TV, radio, and internet ads, you might believe that testosterone is a mysterious hormone and that not having enough—whatever that means—should be avoided and corrected immediately pharmaceutically if you want to be a virile, healthy man. Although it’s true that testosterone (T) is a potent and important hormone, many myths and misunderstandings have evolved about it, especially the hype that introducing more testosterone into your body will resolve all of your woes. It’s time to set the record straight and begin really understanding testosterone.
What Is Testosterone?
Testosterone is a steroid hormone produced primarily by the testes, with some minor help from the adrenal glands, throughout your lifetime. The manufacturing process is in full swing typically up until about age 30, when levels of the hormone begin to taper off.
Also referred to as T, testosterone is an androgen, one of two main steroid hormones (androsterone is the other one) that stimulates the development of male sexual characteristics and promotes male secondary sex characteristics. It is the most potent of the naturally occurring androgens, of which there are about half a dozen.
What are those sexual characteristics? Take a momentary trip down memory lane to middle school and sex education class when you were told how testosterone was the male sex hormone responsible for increasing your muscle mass, deepening your voice, growing hair between your legs and on your chest, and making it possible for you to become a father unless you practiced safe sex. You may or may not also remember being told that testosterone also plays a role in building and maintaining bone density and muscle strength while indirectly reducing the risk of stroke, diabetes, and heart disease by helping men lower their cholesterol, reduce fat, and burn glucose more efficiently.
What Are the Types of Testosterone?
If you listen to the commercials, you might think there’s only one type of testosterone, when in reality there are three. When talking about the types of testosterone, it’s also important to mention a protein called sex hormone binding globulin (SHBG), which is intimately involved in how the types of testosterone function in the body.
Free testosterone is the form of the hormone that is not attached or bound to binding proteins. This is the active form of the hormone that is available for the body’s use, but it makes up only about 0.3 to 5 percent of the total amount of testosterone in the body. A 2 percent free testosterone value is considered to be optimal.
Bioavailable testosterone is the sum of free testosterone and testosterone that is bound to a protein called albumin, the main protein in the fluid portion of the blood. About one-third to 40 percent of the testosterone in a man’s body is bound to albumin. Fortunately, the good thing about bioavailable testosterone is that albumin can release the hormone when the body needs more T.
Total testosterone is the sum of bioavailable testosterone (about one third) and testosterone that is attached to sex hormone binding globulin (SHBG; about two thirds). When you have your testosterone levels measured, this is usually the value your doctor will give you, but it does not provide you or your doctor with an accurate account of your testosterone status. The most important percentage to know is your free testosterone, since it is the active form.
About two thirds of the testosterone in the body of a young, healthy male is bound to SHBG, which renders it unavailable to the body. As men get older or if they are ill, SHBG becomes more active and attaches itself to more and more testosterone, which in turn reduces the amount of free testosterone. Therefore, the less SHBG a man has, the higher his level of free (active) testosterone.
Therefore, the secret is to find ways to boost your level of free testosterone, and the answer is not the use of testosterone replacement therapy! Rather, you can naturally reduce the activity of SHBG and/or engage in activities that help more bioactive testosterone break free from albumin.
Why Do You Need Testosterone?
Men need testosterone throughout their lifetime. The hormone is essential for the development of male reproductive organs and the promotion of sexual characteristics such as growth or body hair, increased muscle, deepening voice, and sufficient bone mass. Testosterone also is important after a male’s developing years to help maintain muscle strength and tone, support sexual prowess and libido, promote red blood cell production, and influence mood.
Testosterone doesn’t perform all of these functions alone; it works with and is influenced by other factors. For example, advancing age is associated with certain unwelcome body changes and symptoms often associated with low testosterone. A clear understanding of testosterone, how it works, what healthy T levels are, and how you can successfully beat those unwanted symptoms without turning to testosterone replacement therapy will result in better sexual and overall health and well-being.
What’s Normal, Optimal, and Low Testosterone?
The answer to this question is, it depends. The range of what is considered to be a “normal” testosterone level is broad and depends largely on man’s age. In addition, experts and testing laboratories don’t completely agree on what is considered to be “normal” and “low” testosterone. For example, here are some general values for total, free, bioavailable, and low testosterone levels.
The normal or healthy range of total T for men age 20 to 39 years is 270 to 950 ng/dL (nanograms of T per deciliter of blood); for men 40 to 59, 350 to 890 ng/dL; and for men 60 and older, 350 to 720 ng/dL. As for an optimal level, that is highly individual and depends on the man.
For free T, normal levels range from: 5.05 to 19.8 ng/dL for men 25 to 29; 4.86 to 19.0 ng/dL for ages 30 to 34; 4.65 to 18.1 ng/dL for ages 35 to 39; 4.46 to 17.1 ng/dL for ages 40-44; 4.26 to 16.4 ng/dL for ages 45-49; 4.06 to 15.6 ng/dL for ages 50-54; 3.87 to 14.7 ng/dL for ages 55-59; 3.67 to 13.9 ng/dL for ages 60-64; 3.47 to 13.0 ng/dL for ages 65-69; and 3.28 to 12.2 ng/dL for ages 70 to 74.
For bioavailable T, normal levels are 83 to 257 ng/dL for men 20 to 29; 72 to 235 ng/dL for men 30 to 39; 61 to 213 ng/dL for men 40 to 49; 50 to 190 ng/dL for men 50 to 59; and 40 to 168 ng/dL for men 60 to 69. No ranges have been established for men 70 years and older.(9)
The professional definition of clinically low testosterone is a value less than 200 ng/dL, although you will see a range of less than 220 to 300 ng/dL in some publications. Men who have testosterone levels in this very low range are usually diagnosed as having hypogonadism, or true testosterone deficiency, in which the body does not produce enough of the hormone because of (typically) medical reasons. In such cases, testosterone replacement therapy is the prescribed treatment. Hypogonadism is the only condition for which testosterone should be prescribed.
What’s the Bottom Line When It Comes to Low T?
If you remember nothing else, take away this important truth about testosterone. It will help you resist the tempting commercials hawking testosterone replacement and relieve some of the stress you may feel about low T.
As you can see, there is considerable variation in each of these ranges. They are meant as guidelines only, as each man’s individual needs are different. Two men of the same age can have T levels that are vastly different—say, 400 ng/dL and 750 ng/dL—and both men can be energetic, lean, viral, and successful.
However, some men who have testosterone levels in the higher range can experience fatigue and zero sex drive while other men with low T can feel and look great. The bottom line is, T values alone don’t matter that much. Testosterone levels are highly individualized. Your body works in synch with numerous other factors (e.g., genetics, lifestyle, environmental influences, other hormones) that are involved in the symptoms you may be experiencing. Hormones are especially critical, because if you take testosterone replacement to boost your T levels, you may be throwing fuel on the fire, creating an unbalanced hormone environment that will not serve your needs. The saner, healthier way to approach low T in the first instance is to allow the body to restore balance naturally using natural lifestyle treatments.