Why is my testosterone low?
Low testosterone is a finding, not a final answer. The cause decides whether it can be reversed, which treatment fits and whether anything else needs checking. One blood test, LH, does most of the sorting.
The short answer
- Check LH to find where the problem isHigh LH means the testicles aren't keeping up. Low or normal LH means the signal from the brain is weak.
- Most cases are the signal type, and many are reversibleExtra weight, sleep apnea, opioids, steroid pills and past steroid use are the usual drivers.
- A few patterns need a closer lookVery low levels, high prolactin, or headaches and vision changes call for a pituitary evaluation.
How your body makes testosterone
Testosterone is made in the testicles, but the order to make it starts in the brain. The hypothalamus releases GnRH, which tells the pituitary to release LH and FSH. LH tells the testicles to make testosterone; FSH drives sperm production. When testosterone rises, it signals the brain to ease off. That feedback loop is why a problem anywhere along it can lower your level, and why LH tells us where.
The same feedback explains why testosterone therapy and anabolic steroids switch off your own production and lower sperm counts. The brain sees plenty of testosterone and stops sending LH and FSH.
Reading your lab pattern
Put your testosterone and LH side by side. Your doctor may add FSH, prolactin and SHBG to sharpen the picture.
| Pattern | What it usually means | Next step |
|---|---|---|
| Low T, high LH | Primary. The testicles can't respond fully to the signal. | FSH, semen analysis if fertility matters, karyotype if testicles are small |
| Low T, low or normal LH | Secondary. The brain's signal is weak. Most common pattern. | Prolactin, look for weight, sleep apnea and medicine causes; iron studies in some men |
| Low T, high prolactin | Prolactin is suppressing the signal. Can be a pituitary growth or a medicine. | Repeat prolactin; if still high, endocrinology and pituitary MRI |
| Low T, low SHBG, extra weight | Total may understate the active amount. | Calculated free testosterone |
| Normal or high T, very low LH | Testosterone is coming from outside: a prescription, steroids or a supplement spiked with them. | Review everything you take |
Secondary causes: a weak signal from the brain
This is where most men land, and where the most can be fixed without lifelong treatment. Several of these often stack together.
The single most common driver. Fat tissue converts testosterone to estrogen, and obesity dampens the brain's signal. Losing weight raises testosterone, and the more you lose, the bigger the rise.
Low testosterone is common in men with diabetes. Better blood sugar control and weight loss help both.
Most testosterone is made during sleep. Loud snoring, gasping at night or waking unrefreshed are reasons for a sleep study.
Long-term opioids suppress LH in many men. Levels usually recover if the dose comes down or stops. Never stop opioids suddenly; work with your prescriber.
Prednisone and similar medicines lower testosterone, especially at higher doses or with long use.
These switch off your own production. Recovery can take many months, and sometimes longer. Medicines like clomiphene or hCG can help restart it.
Regular heavy drinking lowers testosterone and can damage the liver, which raises SHBG.
Acute illness, big calorie deficits and very high training loads all lower testosterone for a while. Retest once you've recovered.
Usually benign. Often treated with medicine rather than surgery. Some drugs, including certain antipsychotics and anti-nausea medicines, also raise prolactin.
Non-prolactin pituitary tumors, past head injury or brain radiation, iron overload (hemochromatosis) and rare inherited conditions such as Kallmann syndrome.
Primary causes: the testicles can't keep up
Here the brain is calling loudly, so LH is high. These causes usually don't reverse with lifestyle changes, and fertility is often affected too.
The most common genetic cause of low testosterone, affecting roughly 1 in 600 men, many of whom are never diagnosed. Small, firm testicles are the main clue. A blood test called a karyotype confirms it.
Some cancer treatments damage testosterone-making cells. Effects can be partial or delayed by years.
Loss or damage of testicular tissue lowers output, especially if both sides are affected.
Inflammation of the testicles after puberty can cause lasting damage.
Testicular output declines slowly with age and the signal often weakens too, so many older men have a mix of both patterns.
When it needs more than lifestyle changes
Other tests your doctor may add depending on the pattern:
| Test | Looks for |
|---|---|
| Ferritin and iron saturation | Iron overload (hemochromatosis), which can damage the pituitary and testicles |
| Hemoglobin A1c | Diabetes or prediabetes |
| TSH | Thyroid problems, which share many symptoms and change SHBG |
| Sleep study | Obstructive sleep apnea |
| Karyotype | Klinefelter syndrome, when LH and FSH are high and testicles are small |
| Semen analysis | Sperm production, if you want children now or later |
Common questions
Will losing weight really raise my testosterone?
Usually, yes, when weight is part of the cause. Modest weight loss produces a modest rise; large weight loss, such as after bariatric surgery or with newer weight-loss medicines, can bring levels back to normal in many men.
Does stress lower testosterone?
Short bursts of physical or emotional stress can lower it temporarily. Long-term stress mostly acts through poor sleep, weight gain and alcohol, which are the pieces to work on.
Does masturbation or watching porn lower testosterone?
There's no good evidence that either causes lasting changes in testosterone levels.
What about plastics, soy or "estrogenic" foods?
At normal dietary amounts, soy hasn't been shown to lower testosterone in men. Chemicals like phthalates are linked to small differences in population studies, but they're rarely the explanation for an individual man's clearly low level.
I used steroids years ago. Will my levels come back?
Many men recover over months to a couple of years, but some don't fully. If you want children or are still low after stopping, a urologist can use clomiphene or hCG to help restart your own production.
See what's driving yours
Enter your testosterone, LH and anything that applies, or upload your lab PDF. My Testosterone Levels sorts out the likely pattern and the tests to ask about.
Open the My Testosterone Levels checkerSources
- Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. J Urol 2018;200:423–432. Reviewed and validity confirmed 2024.
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103:1715–1744.
- Grossmann M, Matsumoto AM. A perspective on middle-aged and older men with functional hypogonadism. J Clin Endocrinol Metab 2017;102:1067–1075.
- Corona G, et al. Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: a systematic review and meta-analysis. Eur J Endocrinol 2013;168:829–843.