Doctor's Notes on Low Testosterone (Low-T)
Low testosterone (low-T) describes an abnormal level of the hormone testosterone, a steroid hormone produced in the adrenal glands of both sexes, and in the testes of males and the ovaries of females. Low testosterone is considered to be below 300 ng/dl in male patients, although some doctors suggest the normal range is 270 – 1070 ng/dl. Other terms for low-T include hypogonadism (primary, secondary and tertiary, depending on the cause of low-T) and testosterone deficiency (TD).
Symptoms of low testosterone (low-T) include erectile dysfunction, Reduced sex drive, reduced or absent orgasm, reduced or absent spontaneous erections; loss or reduction of pubic, armpit, or facial hair; depression, size reduction of testes, breast discomfort or enlargement, hot flashes or sweating, reduction in strength, sleep disturbances, or memory reduction. Other symptoms of low testosterone (low-T) that may be seen in examination or tests done by a doctor include anemia, osteoporosis, reduced or absent sperm production, infertility, or increased body fat (body mass index). Many of these same symptoms may be see in women with low-T except for the male-specific symptoms.
Low Testosterone (Low-T) Symptoms
There are many signs and symptoms of low-T. The most common sign and symptoms that bring males to their doctors is erectile dysfunction (poor or no erection of the penis). However, there are many other signs and symptoms that also may occur:
- Reduced sex drive
- Reduced or absent orgasm
- Reduced or absent spontaneous erections
- Loss or reduction of pubic, armpit, or facial hair
- Size reduction of testes
- Breast discomfort or enlargement
- Hot flashes or sweating
- Reduction in strength
- Sleep disturbances
- Memory reduction
Other signs may be seen in examination or tests done by a doctor
- Anemia (decrease in red blood cells)
- Reduced or absent sperm production; infertility
- Increased body fat (body mass index)
Many of the above may be see in women with low-T except for the male specific symptoms.
Low Testosterone (Low-T) Causes
The causes of low-T are many and can be separated into three categories: primary, secondary, and tertiary.
Primary types of low-T or primary hypogonadism refer to the injury or failure of organs that are the main producers of testosterone, the testes and ovaries. Causes of primary low-T include scrotal or testicle injuries, undescended testicles, mumps, orchitis, chemotherapy or radiation therapy, chromosomal abnormalities, ovarian failure or surgical removal, and aging.
Causes of secondary low-T or secondary hypogonadism are related to the pituitary gland regulation of testosterone, while tertiary low-T or tertiary hypogonadism is related to the hypothalamus (a gland within the brain that regulates the pituitary and other glands) regulation of testosterone. Most causes of secondary and tertiary low-T are the same for the pituitary and hypothalamus; in addition, the causes may affect both at the same time. Causes of secondary and tertiary low-T include:
- Tumors associated with the pituitary or hypothalamus
- Chemotherapy of nearby tumors
- Gland malformations
- Decreased blood flow to glands for any reason
- Gland inflammation due to disease (HIV, tuberculosis, sarcoidosis)
- Taking anabolic steroids to enhance performance or muscle mass (athletes, body builders)
There are other causes that reduce testosterone that do not fit well into the above categories. Most notable is obesity, in which fat cells enhance conversion of testosterone to estrogen. Diseases such as diabetes, renal disease, COPD, high blood pressure, and lifestyles that include smoking and drug abuse also contribute to low-T.
Other less frequent causes are modified cell receptors for testosterone and unusual cell mechanisms that are rarely identified.
Testosterone is a hormone that is necessary for proper muscular development and masculinity. Testosterone is made in the testes (testicles). Women also have testosterone, but in much smaller amounts than in men. If testosterone levels are below normal, a doctor may prescribe one of several types of treatments. However, there is debate about who needs to be treated.
What Does Testosterone Do?
- Fuels the sex drive
- Adds muscle mass
- Regulates mood
- Regulates bone strength
Low Testosterone (Low T) : Test Your IQ of Men's Conditions QuizQuestion
Testosterone is a chemical found only in men.See Answer
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.