What is testosterone?
Testosterone is a male sex hormone that is produced by the testicles and responsible for the development of male secondary sexual characteristics, such as facial and body hair, a deep voice, and increased muscle mass. It is also involved in a variety of other processes in the body, including bone density, red blood cell production, and sperm production.
How is testosterone produced in the body?
Testosterone is produced in the testicles by Leydig cells. It is synthesized from cholesterol through a complex process involving several enzymes and hormones, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
What is the normal range for testosterone levels in men?
The normal range for testosterone levels in men varies depending on age and other factors. In general, a normal testosterone level for a man is considered to be between 300 and 1,000 nanograms per deciliter (ng/dL). However, it is important to note that normal testosterone levels may vary between different laboratories and may be affected by a variety of factors, including age, race, and overall health.
What are the symptoms of low testosterone (also known as hypogonadism)?
Symptoms of low testosterone may include:
- Decreased sex drive
- Erectile dysfunction
- Decreased muscle mass and strength
- Increased body fat
- Decreased bone density
- Changes in mood and cognitive function
How is low testosterone diagnosed?
Low testosterone is typically diagnosed based on symptoms and a blood test to measure testosterone levels. A testosterone level below 300 ng/dL is generally considered low, although some experts consider a level below 350 ng/dL to be low as well.
What are the potential causes of low testosterone?
There are several potential causes of low testosterone, including:
- Testicular injury or infection
- Testicular surgery
- Chemotherapy or radiation therapy
- Certain medications
- Chronic illness, such as HIV/AIDS or diabetes
How is low testosterone treated?
Treatment for low testosterone may include testosterone replacement therapy, which can be administered in various forms, including gels, patches, injections, and pellets. The appropriate form of therapy will depend on the individual's specific needs and preferences.
Can testosterone levels be too high?
Yes, testosterone levels can be too high, a condition known as hypergonadism. High testosterone levels in men can cause symptoms such as acne, male pattern baldness, and prostate problems.
What are the potential causes of high testosterone in men?
High testosterone levels in men may be caused by a variety of factors, including:
- Testicular tumors
- Congenital adrenal hyperplasia
- Anabolic steroid abuse
- Certain medications
De Groot LJ, Abalovich M, Alexander EK, et al. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2012;97(8):2543-2565.
Kahaly GJ, Dillmann WH. Thyroid hormone synthesis and secretion. Endocr Dev. 2010;17:11-38.
National Cancer Institute. Thyroglobulin Test. https://www.cancer.gov/about-cancer/diagnosis-staging/tests/thyroglobulin-test.
National Institute of Diabetes and Digestive and Kidney Diseases. Thyroid Tests. https://www.niddk.