Breast development in men (gynecomastia) Sweating and hot flashes Bone fractures caused by minor trauma

16.07.2026

Low Testosterone in Men

Symptoms, Diagnosis, and What Really Helps

By Dr. Rahel Sahli, Endocrinologist, Ärztezentrum Ittigen

Fatigue, lack of energy, loss of libido—many men attribute these symptoms to stress or aging. But they could also be caused by low testosterone. What are the typical signs? When should you see a doctor? And what can you expect?

In this article, you’ll learn what symptoms are typical, when a medical evaluation is advisable, and what treatment options are available.

What is testosterone deficiency?

Testosterone is the most important male sex hormone. It affects muscle mass, bone density, libido, mood, energy, and metabolism. A deficiency—medically known as “hypogonadism”—can have various causes: disorders of the testicles or the pituitary gland, as well as obesity, chronic illnesses, or the natural aging process. Testosterone levels in men begin to decline slowly as early as age 35.

Typical symptoms

Sexual symptoms are the most common and the most specific:

Loss of libido
Erectile dysfunction
Fewer spontaneous erections

Other typical signs:

Breast development in men (gynecomastia)
Sweating and hot flashes
Bone fractures caused by minor trauma

Less specific but common symptoms:

Persistent fatigue and loss of energy
Depressed mood
Sleep disturbances
Decrease in muscle mass and strength
Increase in abdominal fat

When and how are measurements taken?

Blood samples must be collected under standardized conditions:

Time: In the morning between 7 and 10 a.m.
Condition: Fasting
At least two measurements on different days

A single low reading does not constitute a diagnosis. Only the combination of low lab values and corresponding symptoms provides the complete picture.

Testosterone and Depression—A Two-Way Relationship

Low testosterone levels can be a cause of depression. But conversely, depression can also lead to a “functional” testosterone deficiency. For men with depression, I recommend asking specifically about other symptoms of testosterone deficiency—and if the overall picture adds up, conducting laboratory testing.

What Does Therapy Offer—and What Doesn't It?

What therapy can do: improve libido, energy, mood, muscle mass, and bone density—if a deficiency is the cause of the symptoms. What it isn't: a fountain of youth, a performance enhancer, or a substitute for a healthy lifestyle.

Lifestyle as the First Step

Sleep: A significant portion of testosterone production occurs at night.
Weight: Even a 5% weight loss can measurably improve testosterone levels.
Exercise: Adequate exercise has a positive effect on testosterone levels. However, balance is crucial: Chronic overtraining without sufficient recovery can lead to a drop in testosterone levels and, at the same time, to elevated cortisol levels.
Stress: Chronic stress increases cortisol and inhibits testosterone production.

I'm happy to be here for you

Dr.Sahli

Endocrinologist

Ärztezentrum Ittigen

Dr. Sahli studied medicine at the University of Zurich and graduated in 1994. After completing her residency at various renowned hospitals in Switzerland, including Inselspital Bern, she earned her board certification in Endocrinology and Diabetology in 2005 and in Internal Medicine in 2007. From 2008 to 2011, she served as a senior physician at the University Clinic for Endocrinology, Diabetology, and Clinical Nutrition at Inselspital Bern. She then worked at the STEPS Metabolic Center in Biel and, starting in 2014, at the Sanacare Group Practice in Bern. In addition to her clinical work, she is active in various professional committees and has many years of expertise in the fields of diabetes, metabolic disorders, and endocrinology. She joined the team at the Ittigen Medical Center in 2026 and brings her extensive experience to the care of her patients.

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