Hypogonadism means the body is not producing enough testosterone for normal function. The important part is that it is not diagnosed from symptoms alone.
Fatigue, low libido, poor mood, and muscle loss can happen for many reasons. Clinical guidelines recommend compatible symptoms plus consistently low testosterone on appropriate testing.
Major endocrine guidelines recommend diagnosing hypogonadism only when symptoms or signs consistent with testosterone deficiency are paired with unequivocally and consistently low testosterone. Repeat morning testing and evaluation of the cause are important.
Common Symptoms
Possible symptoms include low sexual desire, fewer spontaneous erections, reduced energy, lower muscle mass, increased body fat, low mood, infertility, and reduced bone density.
These symptoms are not specific to testosterone. Sleep apnea, depression, thyroid disease, medication effects, obesity, chronic illness, and calorie restriction can create a similar picture.
How Testosterone Should Be Tested
Testing usually starts with morning total testosterone because levels change during the day. If the first result is low, guidelines recommend repeating the test rather than diagnosing hypogonadism from one number.
Free testosterone, SHBG, LH, FSH, prolactin, and other tests may be useful depending on the result and the person's history.
Primary vs. Secondary Hypogonadism
Primary hypogonadism starts in the testes. Secondary hypogonadism involves the pituitary or hypothalamus, the parts of the brain that signal the testes to make testosterone.
LH and FSH help separate these patterns. That distinction matters because the cause and treatment can be different.
Common Causes Worth Looking For
- Testicular injury or disease
- Pituitary or hypothalamic disorders
- Obesity and metabolic disease
- Severe illness or chronic inflammation
- Sleep problems, including sleep apnea
- Some medications, especially opioids and glucocorticoids
- Very low calorie intake or excessive endurance training
- Age-related changes
Finding the cause can reveal a problem that should be treated directly rather than jumping straight to testosterone.
Treatment Depends on the Cause and the Goal
For men with confirmed hypogonadism and appropriate symptoms, testosterone therapy can improve sexual symptoms, body composition, bone density, and other outcomes.
TRT is not appropriate for every man. Fertility plans, prostate and blood issues, untreated severe sleep apnea, cardiovascular history, and other factors can affect the decision.
The Bottom Line
Do not diagnose low testosterone from a symptom list or one afternoon blood test. Confirm the pattern, look for the cause, and decide whether treatment fits your goals and risks.
That approach is slower than guessing, but it is much more useful.
What Not to Do
Do not start testosterone because one blood test is near the bottom of a reference range. Do not assume every symptom after 40 is hormonal. And do not ignore fertility before starting a treatment that can suppress sperm production.
A good workup should answer two questions: is testosterone truly low, and why?
For related reading, explore testosterone replacement therapy, what testosterone does in men, and our Hormones section.
Common Questions About Hypogonadism
Can obesity lower testosterone? Yes. Excess body fat and metabolic disease are common contributors to functional low testosterone, and weight loss can improve levels in some men.
Can sleep apnea affect testosterone? Poor sleep and untreated sleep apnea can contribute to fatigue and hormonal problems. They are worth addressing whether or not TRT is used.
Is low-normal testosterone always unhealthy? No. Reference ranges are broad, and symptoms plus repeated measurements matter more than one number by itself.
