Causes of Low Testosterone
There are several possible causes of low testosterone, such as problems in the testes, the pituitary gland, or the hypothalamus. When the problem is due to the testes, it is called primary male hypogonadism. When the problem is with the pituitary gland or hypothalamus, it is called secondary male hypogonadism. Regardless of the cause, low testosterone can usually be treated successfully using replacement medications.
Low testosterone can be caused by anything that affects the testes, pituitary gland, hypothalamus, or the messengers that communicate between these glands. Normally, the hypothalamus (in the brain) sends hormonal messages to the pituitary gland (in the brainstem), which in turn sends hormonal messages to the testes. If the problem lies directly within the testes, this is known as primary male hypogonadism.
If the problem is with the pituitary gland or hypothalamus, it is known as secondary male hypogonadism. Sometimes, problems in the hypothalamus (not the pituitary) are known as tertiary male hypogonadism, although usually these types of problems are lumped together with the secondary male hypogonadism group.
Keep in mind that while low testosterone is certainly more common as men age, low levels associated with symptoms should not automatically be considered a normal part of aging.
Some possible low testosterone causes that are attributable to problems within the testes include:
- A variety of different genetic conditions, such as Klinefelter syndrome
- Mutations in the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) receptors in the testes
- Undescended testicles (cryptorchidism)
- Abnormal enlargement of the vein within the scrotum (varicocele)
- Infections, such as mumps
- Injury to the testes
- Certain medications, such as ketoconazole (Nizoral®), corticosteroids (such as prednisone), or chemotherapy drugs
- Various chronic diseases, such as cirrhosis of the liver, kidney failure (renal failure), or acquired immune deficiency syndrome (AIDS).
The timing of the onset of symptoms, as well as the specific symptoms themselves, can help guide your healthcare provider when attempting to diagnose the cause of primary hypogonadism.