What is primary hypogonadism?
A primary hypogonadism is a form of hypogonadism in which the cause lies directly in the testicles. The testicles are no longer able to produce sufficient testosterone or sperm, even though they are sufficiently hormonally stimulated by the brain.
Because testosterone production is reduced, the body tries to compensate for this deficiency. The pituitary gland therefore secretes increased amounts of the hormones LH (luteinizing hormone) and FSH (follicle-stimulating hormone). Primary hypogonadism therefore typically presents with low testosterone levels and simultaneously elevated LH and FSH levels.
Primary hypogonadism is one of the most common causes of testosterone deficiency and can be either congenital or acquired during life.
How does primary hypogonadism develop?
In primary hypogonadism, the disorder lies directly in the testicles. Although the hormonal feedback loop between the brain and the testicles basically works, the testicles do not respond sufficiently to the signals from the pituitary gland.
This results in less testosterone being produced. At the same time, sperm production may also be impaired, so that fertility problems often occur in addition to a testosterone deficiency. How testosterone and fertility are related is explained in our article Testosterone and fertility.
What causes can primary hypogonadism have?
Primary hypogonadism can be caused by various congenital or acquired diseases.
The most common causes include:
- genetic disorders, such as Klinefelter syndrome
- Undescended testicles in childhood
- Testicular injuries
- Testicular torsion
- Testicular infections (orchitis)
- Testicular tumors or their treatment
- Chemotherapy or radiation therapy
- Surgical removal of one or both testicles
- Age-related decline in testicular function
Depending on the cause, the testosterone deficiency may be permanent or vary in severity.
What symptoms occur in primary hypogonadism?
The symptoms often correspond to those of a testosterone deficiency and usually develop gradually.
Typical symptoms are:
- Reduced libido
- Erectile dysfunction
- Fatigue and exhaustion
- Reduced muscle mass
- Increased body fat
- Reduced physical performance
- Concentration difficulties
- Depressive mood
- Reduced beard growth
- Fertility problems
The symptoms that occur depend on several factors, including the age of the affected person and the severity of the testosterone deficiency.
How is primary hypogonadism diagnosed?
The diagnosis is based on the symptoms as well as targeted hormone testing.
Typically, the following laboratory findings are observed:
- Total testosterone is low
- Free testosterone is low
- LH is elevated
- FSH is elevated
Depending on the question, other laboratory values may be determined, including:
- SHBG
- Estradiol
- Prolactin
If a genetic cause is suspected, genetic testing may also be useful.
How does primary hypogonadism differ from secondary hypogonadism?
The crucial difference lies in the cause of the disorder.
In primary hypogonadism, the functional disorder lies directly in the testicles. The brain produces sufficient LH and FSH, but the testicles cannot respond adequately.
In secondary hypogonadism, however, the cause lies in the hypothalamus or pituitary gland. Insufficient amounts of regulatory hormones are produced there, so the testicles are not sufficiently stimulated.
The determination of LH and FSH is therefore an important part of the diagnosis.
How is primary hypogonadism treated?
Treatment is based on the cause as well as the affected person's symptoms.
If there is a permanently low testosterone level with corresponding symptoms and there are no contraindications, testosterone replacement therapy (TRT) may be considered.
If, on the other hand, the person is currently trying to conceive, alternative treatment strategies must be considered, as testosterone replacement therapy can suppress the body's own sperm production.
Regular medical check-ups are important during treatment to monitor effectiveness and tolerability.
Conclusion
Primary hypogonadism is a form of testosterone deficiency in which the cause lies directly in the testicles. Typically, testosterone levels are low while LH and FSH levels are elevated.
Targeted hormone testing makes it possible to distinguish it from secondary hypogonadism and forms the basis for choosing the appropriate treatment.