What Causes Low Testosterone in Men Under 40?

Feeling unlike yourself in your twenties or thirties can raise questions about testosterone. For men in San Gabriel, an evaluation starts with understanding the cause of persistent symptoms and whether hormone testing is appropriate.

Can younger men have low testosterone?

Yes. Low testosterone can occur before age 40. Possible contributors include obesity, certain medicines, sleep disorders, testicular problems, and conditions affecting hormone signals from the brain. Symptoms alone cannot establish the diagnosis. The Endocrine Society recommends confirming low levels with repeat morning testing alongside a symptom assessment.

Sleep, illness, and recovery can affect the picture

Sleep disorders, severe illness, poor nutrition, and excessive exercise can be associated with lower testosterone. Tell your clinician if testing followed an illness or a period of unusual physical strain. A result needs context before it becomes a treatment decision. Source: Endocrine Society.

Weight and metabolic health deserve attention

Obesity can affect testosterone and reduce SHBG, a protein that carries the hormone in the blood. This can complicate interpretation of a total testosterone result. Your clinician may consider free testosterone when appropriate rather than treating every low total number as the same problem. Source: MedlinePlus.

Medicines and anabolic steroids can contribute

Opioid pain medicines and some corticosteroids can affect testosterone production. Anabolic steroid use is another possible contributor. Bring a complete list of prescriptions, supplements, and hormone products to your appointment, including products obtained outside a pharmacy. Do not stop prescribed medication without discussing it with the prescribing clinician. Source: Endocrine Society.

Sometimes the cause involves the testicles or hormone signals

Testicular injury, certain infections, cancer treatments, and genetic conditions can impair testosterone production. Other causes involve the pituitary or hypothalamus, which help regulate hormone signals. Identifying the source matters because different causes can require different management. Sources: MedlinePlus and Endocrine Society guideline.

What should an evaluation include?

A clinician reviews your symptoms, history, medicines, and examination findings. When testosterone deficiency is suspected, repeat morning fasting testosterone testing helps confirm it. LH and FSH testing can help distinguish testicular causes from problems with hormone signaling. Additional testing depends on the findings. Source: Endocrine Society guideline.

For more detail about the testing conversation, read our guide to lab work before starting TRT. Bring prior results and a short timeline of what changed so the visit can focus on your questions.

Does confirmed low testosterone always mean TRT?

Treatment depends on the cause. Some contributing conditions can improve without testosterone replacement; other forms of hypogonadism need ongoing treatment. If TRT is considered, discuss expected benefits, alternatives, and monitoring. Testosterone can raise blood pressure, a risk highlighted in the FDA's product-labeling update. Sources: MedlinePlus and FDA.

Discuss fertility before starting testosterone

Testosterone treatment can suppress sperm production. If biological children are part of your plans, raise that before treatment starts. A reproductive specialist can discuss evaluation, alternatives, and whether sperm preservation is appropriate. Recovery after stopping testosterone can take time; treatment should not begin with an assumption that fertility will be unaffected. Source: American Society for Reproductive Medicine.

Frequently Asked Questions

Is one low testosterone result enough?

No. A diagnosis generally requires relevant symptoms or signs together with consistently low testosterone, confirmed with repeat testing. Ask how timing and your health at the time of the blood draw affect interpretation. Source: Endocrine Society guideline.

Can treating the underlying cause help?

Sometimes. Reversible contributors may improve with appropriate care, while permanent testicular or hormonal disorders may need longer-term management. The cause helps determine the plan. Source: MedlinePlus.

Can I start TRT if I want children soon?

Tell your clinician before starting. The Endocrine Society recommends against testosterone therapy when near-term fertility is planned. A reproductive specialist can help assess your options. Source: Endocrine Society guideline.

Take the next step in San Gabriel

Prepare three questions for your visit: What could explain my symptoms? What testing will clarify the cause? How would my health and family plans affect treatment choices?

Explore testosterone therapy at Ultimate Male or request a consultation to discuss an evaluation in San Gabriel. Ultimate Male also serves patients in Downey.