Testosterone Levels: How do they change over time?

There is increasing evidence that some men go through hormonal changes as they age. The most common hormone attributed to these male hormonal changes, often called male menopause, is testosterone. Most of the testosterone (98%) is bound to proteins in plasma, leaving only a small amount of free hormone. Testosterone production is regulated by gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) in a negative feedback system.

The loss of testosterone may be because of 3 general reasons:

- The number and volume of leydig cells in the testicles decrease with age at about 1% per year after the age of 50 years.
- Aging leads to loss of the LH pulse amplitude as well as a decreased response of LH to GnRH.
- Increase in SHBG lead to a further decrease in free testosterone.

Other factors may also play a role in the levels of testosterone in men, like genetic composition, alcohol (which is known to suppress testosterone by testicular cytotoxicity), decrease blood flow to the testicles and smoking. Obesity itself may play both a causative and effectual role in decreased testosterone levels.

The effects of ageing on testosterone levels may be confounded by other variables that must be considered in the assessment of androgen status. Older men recruited from medical clinics have lower testosterone levels than community-dwelling populations, suggesting that concurrent ill health depresses testosterone levels.

Chronic illness, prescription medication, obesity or excessive alcohol has been associated with a substantial reduction in testosterone levels. A direct effect on serum testosterone levels may be seen with medications such as opiates (change in LH pulse amplitude) or anticonvulsants (hepatic enzyme induction). Surprisingly, various lung disorders have been found to reduce testosterone levels irrespective of age, the effect being more marked in those with lung cancer.

The effects of smoking on total testosterone levels are contradictory and unclear. Elevated levels of the order of 9-25% have been reported by some studies in middle-aged and older smokers while some other studies have identified an inverse relationship between cigarette smoking and testosterone levels.

The effects of alcohol upon testosterone are dependent upon the pattern and duration of usage. Although alcohol inhibits testosterone production but sustained stable alcohol intake in healthy older men has not been found to influence total testosterone levels.

Physical symptoms of abnormal testosterone levels include poor or no erections, decline in sexual activity, loss of muscle strength, fatigue and loss of energy, sleep disturbances, problems in circulations etc while various mental symptoms include decreased intellectual ability and memory loss.

Each individual may experience a different number and type of symptoms. Before assuming that testosterone supplementation is necessary to feel better, you and your doctor may want to run through a variety of diagnostic steps to pinpoint specific causes of your symptoms and a full range of behavioral and other changes that might help you feel better.