Low testosterone: symptoms, causes and treatments

Camilla Freinek
from Camilla Freinek, BSc MSc
on 21.03.2025
Man sitting by a lake, looking at the water

Testosterone is much more than just the ‘male hormone’. It plays a central role in many bodily functions – from muscle building to mood to bone health. But what happens when the body produces too little testosterone? A testosterone deficiency, also known as hypogonadism, can affect well-being and health – and not just in men. Here you can find out everything you need to know about the causes, symptoms and possible ways to support healthy testosterone levels.

What is testosterone deficiency (hypogonadism)?

Testosterone is the most important male sex hormone, but it also plays an important role in the female body. Among other things, it influences:

•    the development of primary sexual characteristics
•    muscle mass and bone density
•    libido and fertility
•    mood and energy levels

A testosterone deficiency occurs when the body does not produce enough testosterone. Diagnosis is based on typical symptoms and low testosterone levels in the blood.

Primary and secondary testosterone deficiency

There are three types of testosterone deficiency:

•    Primary hypogonadism: This is caused by the testicles themselves, which produce too little testosterone.
•    Secondary hypogonadism: A disorder in the brain (hypothalamus or pituitary gland) prevents sufficient testosterone from being produced.
•    Functional hypogonadism: In this case, the testicles and the hormone-regulating brain regions are basically intact, but external factors negatively influence testosterone production (see causes).

Determining luteinising hormone (LH) levels can help distinguish between the first two forms.

Testosterone deficiency vs. andropause

The decline in testosterone in men is often compared to the andropause or ‘male menopause’. Unlike in women, however, this hormonal decline happens gradually. While the age-related decline in testosterone is a natural process, a true testosterone deficiency can be associated with pronounced symptoms.

Causes of testosterone deficiency: age and other factors

From the age of 30 to 40, men slowly but steadily produce less testosterone. This natural process can be so minimal that testosterone levels can still be within the normal range even in old age. In some men, however, testosterone levels drop faster – a decline that is driven by certain factors and can also be associated with symptoms.

Testosterone's ‘enemies’ include:

•    Alcohol: Frequent or excessive consumption of alcohol can have a negative effect on testosterone levels.
•    Stress: Constant stress causes increased release of cortisol, which lowers testosterone production.
•    Abdominal fat: Also known as visceral fat, intra-abdominal fat (abdominal fat) produces messenger substances that inhibit testosterone production. It also triggers certain metabolic processes that convert testosterone into estradiol (the female sex hormone) to a greater extent.
•    Chronic illnesses: Chronic illnesses such as liver cirrhosis, renal insufficiency, type 2 diabetes mellitus, metabolic syndrome or certain types of cancer can also trigger a testosterone deficiency.
•    Severe malnutrition: Malnutrition (e.g. anorexia) can upset the hormone balance not only in women but also in men.
•    Certain medications: certain medications, such as opioids (painkillers), corticosteroids (anti-inflammatories), hormonal contraceptives or some antidepressants, can lower testosterone levels.

Testosterone deficiency symptoms: signs of low testosterone levels

Testosterone deficiency can present with non-specific symptoms such as tiredness, decreased performance, sluggishness, depressive moods and concentration problems, regardless of age and gender. The respective stature and weight can also change. Bone density and muscle mass decrease, while fat is deposited in the abdominal area. In men who have passed puberty, testosterone deficiency can also cause the following symptoms:

Symptoms in men

•    Reduced libido
•    Erectile dysfunction
•    Shrunken testicles
•    Possible fertility problems
•    Loss of muscle mass and strength
•    Reduced bone density
•    Increased abdominal fat
•    Increase in breast fat
•    Increased sweating, including hot flushes
•    Sagging skin
•    Possible hair loss, reduced beard growth, less pubic or underarm hair
•    Tiredness & listlessness as well as depressive moods

Symptoms in women

Women also need testosterone – albeit in smaller quantities. A deficiency can manifest itself in the form of:

•    less energy and motivation
•    loss of libido
•    mood swings

Consequences of testosterone deficiency: effects on health

If left untreated, testosterone deficiency can increase the risk of certain conditions, including:

•    osteoporosis (decreased bone density)
•    cardiovascular disease
•    type 2 diabetes
•    depression and a lack of energy.

Measuring testosterone deficiency: certainty through a testosterone test

Morning blood tests are used for diagnosis because the values fluctuate throughout the day.

When does one start to speak of a testosterone deficiency?

A testosterone deficiency is often diagnosed when the total testosterone level is below 300 ng/dL. Reference values may vary slightly depending on the laboratory.

Remedying testosterone deficiency: means and what you can do

A healthy testosterone level can be supported by a holistic approach. This consists of a combination of nutrition, certain vitamins and minerals, exercise, sleep and more. 

Low testosterone treatment: Testosterone Replacement Therapy (TRT)

If a deficiency has been medically confirmed, testosterone replacement therapy (TRT) can help. Options include:

•    injections (syringes)
•    gels or plasters
•    tablets or implants

TRT should always be carried out under a doctor's supervision.

Desire to have children & testosterone deficiency

Note: TRT can inhibit sperm production. Men who wish to have children should consult a doctor in advance.

Muscle building in testosterone deficiency

Testosterone is a central factor in muscle building. Weight training can help to slow muscle loss. In the case of medical testosterone deficiency, TRT can have a supportive effect.

Conclusion: low testosterone and take action

A testosterone deficiency can affect many aspects of well-being – from muscle strength and energy to libido and mood. The causes are many and varied, ranging from the natural aging process to external factors such as stress or lifestyle. A well-founded diagnosis is crucial in order to take targeted countermeasures. In addition to medical treatments, a healthy diet, regular exercise and enough sleep can help to support hormonal balance. If you notice signs of a testosterone deficiency, don't hesitate to seek medical advice – for more vitality and a better quality of life.

Frequently asked questions about low testosterone

Typical signs include tiredness, loss of libido, muscle loss and mood swings.

Through sexual, physical and mental symptoms such as a lack of drive, abdominal fat gain or erectile dysfunction.

Studies show a possible link between vitamin D deficiency and testosterone deficiency.

Yes, a lack of sleep can negatively affect hormone levels.

A general practitioner, urologist or endocrinologist is the right point of contact.

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