Both men and women can produce testosterone, but men produce more of the hormone than women. Each person’s testosterone levels can vary greatly, depending on gender, age and health. What is testosterone? Testosterone is the main sex hormone produced by men and plays an important role in the testicles, penis, and body hair during puberty. In men, testosterone has important functions in regulating desire and helping the testes produce sperm. In women, testosterone is produced primarily to regulate estrogen. What are normal testosterone levels? Men produce more testosterone than women. Normal testosterone levels range from: 270-1070ng/dL for men 15-70ng/dL for women Pregnant women have 3-4 times more testosterone than non-pregnant women. Testosterone levels are usually highest during puberty and early adulthood. Starting at age 30, it decreases by about 1% each year. What causes low testosterone levels? Low testosterone levels may be caused by: 1. Problems with your own disease, such as severe liver disease; 2. Damage to the testes or pituitary gland; 3. Obesity; and 4. Genetic disorders, such as Creutzfeldt-Jakob syndrome. Lower testosterone levels in older men is a question of whether there are other reasons for low testosterone simply because of getting older? Low Testosterone Symptoms Men with low testosterone levels men may have: 1. Decreased libido, erectile dysfunction or infertility, changes in sleep patterns, and poor sleep 2. Physical changes such as: (1) increased body weight; (2) decreased muscle size and strength; (3) decreased bone density; (4) swelling; and (5) physical hair loss and lower energy levels 3. Emotional changes such as: lack of self-confidence, mood swings, negativity, difficulty concentrating or remembering things. Women with low testosterone levels may have: osteoporosis, fatigue and lack of motivation, decreased desire How is a testosterone level tested? The only way to check for low testosterone levels is to have a blood test. Testosterone levels vary throughout the day and if your blood test levels are low, you should discuss this with your doctor before deciding what next steps to take. Low Testosterone Treatment Testosterone therapy, either capsules or injections, is used to treat low testosterone. It is unclear whether testosterone therapy is beneficial for older men, and testosterone therapy may be harmful in some cases. Risks of testosterone therapy include: (1) acne or other skin reactions; (2) weight gain; and (3) noncancerous growth of the prostate and development of prostate cancer.