Low testosterone and the problem with normal

Introduction

A lot of men hear the same sentence after blood work.

"Your testosterone is normal."

That may be technically accurate. It may also leave too much unexplained.

Testosterone deficiency is also called hypogonadism. It means the body is not producing enough testosterone for normal function. The diagnosis requires symptoms that fit the picture and lab testing that confirms the pattern. Most guidelines call for 2 early morning testosterone measurements.

The lab number still needs a clinician who is willing to think.

A man can fall inside the lab range and still be far below where he used to be when he felt well. A value can look acceptable on paper and still fail to explain the symptoms in front of you.

That is where this conversation gets missed.

The symptoms usually come first

The most specific symptoms of low testosterone are sexual.

Low libido is one. Loss of morning erections is another. Some men have trouble maintaining an erection. Some notice delayed ejaculation. A low or absent sperm count may show up if fertility is being evaluated.

Those symptoms are more specific than the general complaints men often bring in first.

The general symptoms matter too. They are easier to dismiss.

A man may lose muscle mass or strength. He may put on more body fat, especially around the abdomen. He may have less endurance. He may feel tired all the time. Bone density can decline. Body hair, armpit hair, and pubic hair can decrease. Testicle size may decrease. Some men report hot flashes.

Then there are the mental symptoms.

Mood changes. Depression. Poor memory. Difficulty finding words. Trouble concentrating. Work performance starts to slip.

Any one of those symptoms can have other causes. Poor sleep, alcohol, stress, diabetes, depression, medication, anemia, vascular disease, and obesity can all create similar complaints. That is why the evaluation has to be careful.

When those symptoms cluster together, testosterone deserves a serious look.

The 300 number needs context

The common clinical marker for low testosterone is a total testosterone level below 300 ng/dL.

Total testosterone means all the testosterone measured in the blood. Some of it is bound to proteins. Some of it is available for the body to use.

Free testosterone is the unbound fraction. It is the biologically active part. It usually makes up only about 1 to 2% of total testosterone, but it can tell you something the total number misses.

That becomes more important as men age.

Sex hormone-binding globulin, usually called SHBG, tends to rise with age. SHBG binds testosterone. When more testosterone is bound, less may be free and available to tissues, even if the total testosterone number looks acceptable.

So I would want to see both total testosterone and free testosterone as well as SHBG.

At times, bioavailable testosterone is worth checking too. Bioavailable testosterone includes free testosterone plus testosterone loosely bound to albumin, which is a common blood protein. It excludes testosterone bound tightly to SHBG.

That is especially useful when SHBG is elevated.

The normal range can be too wide

I have discussed normal lab values before.

Most lab ranges are built from a population. The values are distributed across what is called a bell curve. The normal range is usually the middle portion of that curve. The "normal" part of the curve is the middle 80% and 10% on each end for "abnormal" (too high or too low).

That tells you where most tested people fall. It leaves the individual question unanswered: where does this man function well?

For example, the normal total testosterone range for a 20 to 30 year old male may run from about 413 to 1,000 ng/dL. For a man over 70, one listed range runs from about 156 to 819 ng/dL.

Those are very wide ranges.

A man could be 72 years old, have a total testosterone of 280, and be told he is close enough to normal depending on the lab range being used. Another man could be at 340, have significant symptoms, and still get dismissed because he is above 300.

A normal label still needs clinical judgment.

Symptoms. Total testosterone. Free testosterone. SHBG. Timing of the blood draw. Other illnesses. Medications. Sleep. Weight. Alcohol. Stress.

The number starts the conversation. A good evaluation keeps going.

Testosterone ranges by age

Source: Everlywell / Hone Health reference ranges.

Source: Everlywell / Hone Health reference ranges from Barry's source document.

Testing has to be done correctly

Testosterone peaks in the morning, usually between about 7:00 and 10:00 AM. That is when the blood draw should be done.

If the first test is low or borderline, it should usually be repeated. Some low readings normalize on a second draw.

The basic evaluation should include total testosterone and free testosterone. Depending on the case, I would also consider SHBG and bioavailable testosterone.

If the testosterone is low, the next question is why.

Luteinizing hormone, or LH, helps answer that. LH is a signal from the brain to the testicles. If LH is high and testosterone is low, the testicles may not be responding properly. If LH is low or inappropriately normal, the problem may be higher up in the hypothalamus or pituitary gland.

The pituitary gland is a small hormone control center at the base of the brain.

Prolactin may also need to be checked. An elevated prolactin level can point toward a pituitary problem, including a pituitary tumor in some cases.

In men over 50, SHBG becomes more relevant because it can change the relationship between total testosterone and free testosterone.

You can order some of these labs yourself through Quest or LabCorp. Interpreting them is a different matter. Numbers need context.

Low testosterone can start in the testicles or in the signal

Primary hypogonadism means the testicles are receiving the proper signal, but they are not producing enough testosterone.

That can be congenital, meaning present from birth. Klinefelter syndrome is one example. Undescended testicles can also cause damage if not corrected. Noonan syndrome, myotonic dystrophy, and Leydig cell hypoplasia can be involved as well.

It can also be acquired over time.

Trauma to the testicle can do it. Surgical removal of a testicle can do it. Chemotherapy and radiation can injure the testicles. Mumps infection can inflame the testicles and reduce testosterone production. Anabolic steroid abuse can suppress the body's own production.

Testosterone treatment can also reduce sperm production. That is a major point for any man still thinking about fertility. Testosterone can still be administered but to preserve fertility other hormone signals should be added.

Secondary hypogonadism means the testicles may be capable of producing testosterone, but they are not receiving enough signal from the brain.

That signal comes through hormones such as luteinizing hormone and follicle-stimulating hormone. Follicle-stimulating hormone, or FSH, is involved in sperm production.

Obesity is one common factor. Fat tissue can convert testosterone into estrogen. Obesity can also suppress the hypothalamic-pituitary axis, which is the brain-to-testicle signaling system.

Type 2 diabetes and insulin resistance are often part of the same picture.

Obstructive sleep apnea can suppress the normal nighttime rise in testosterone. Chronic stress and poor sleep can raise cortisol. Cortisol is a stress hormone, and when it stays elevated, it can interfere with testosterone signaling.

Alcohol use can contribute. Opioid medications can contribute. Chronic illness can contribute.

Aging is part of the story too. Testosterone levels tend to decline about 1 to 2% per year after age 30.

I do not like stopping there.

Aging often travels with other factors: weight gain, poor sleep, metabolic disease, less physical activity, more medications, more stress. If we call all of that "just aging," we may miss things that can be improved.

The useful question

When a man has symptoms, I want to know whether testosterone is part of the problem.

I also want to know what else is going on.

Is he sleeping? Is he drinking every night? Is he carrying abdominal fat? Does he have insulin resistance or type 2 diabetes? Is he using opioids? Did he use anabolic steroids in the past? Does he have untreated sleep apnea? Is chronic stress keeping cortisol high?

Those questions matter before treatment is considered.

Testosterone is powerful physiology. It affects sexual function, muscle, fat distribution, bone density, mood, cognition, and red blood cell production. It should be taken seriously.

The common mistake is reducing the whole question to one lab cutoff.

If you feel like something has changed and your lab report says "normal," read the report carefully. Pay attention to the symptoms that brought you to the test in the first place.

Get the right labs. Get them at the right time. Look at total testosterone and free testosterone. Consider SHBG when it matters. Then talk with someone who will put the symptoms and the numbers together.

That is where the real evaluation begins.