What does low testosterone (low T) mean?
Low testosterone levels in men typically fall below the healthy range of 300 to 1,000 nanograms per deciliter (ng/dL). When your testosterone levels measure below 300 ng/dL, it indicates low testosterone, often referred to as low T.
The hypothalamic–pituitary–gonadal (HPG) axis regulates the production and release of testosterone in the body. The hypothalamus, situated in the brain, secretes gonadotropin-releasing hormone (GnRH), stimulating the pituitary gland to release luteinising hormone (LH) and follicle-stimulating hormone (FSH). These hormones collectively prompt the testes to produce testosterone.
Low testosterone occurs when there's a disruption in the HPG axis, leading to decreased testosterone production. This disruption can result from abnormalities in any of the HPG organs – the hypothalamus, pituitary gland, or testes. While some men may have low T from birth, others may develop it later in life.
Low T is also known by various alternative names, including male hypogonadism, testosterone deficiency, late-onset hypogonadism, male menopause, and andropause.
How many men have low T?
Millions of men are affected by low testosterone (low T) each year. Providing an exact number is challenging due to variations in the definitions used across different studies.
According to the American Urological Association, approximately 40% of men aged 45 and older have low testosterone levels. However, it's important to note that not all of these individuals experience symptoms of low T. Symptoms typically manifest gradually and become more noticeable after the age of 60.
Am I experiencing low testosterone (low T)?
One of the primary methods doctors use to diagnose a condition is by assessing patients' symptoms. Therefore, if you suspect you have low testosterone (low T), your doctor will likely begin by asking you to describe your symptoms or the factors that led you to believe you may have this condition.
Common symptoms experienced by men with low T include:
- Low sex drive
- Low sperm count
- Inability to gain and maintain an erection
- Shrinking testicles
- Low muscle mass
- Loss of body and facial hair
- Increased body fat
- Lack of energy
- Low motivation
- Mood swings
- Depression
- Hot flashes
- Gynecomastia
- Low blood count
Your doctor will also conduct a physical examination to identify signs of low testosterone (low T). If your symptoms suggest a deficiency in testosterone, your doctor may request the following tests to diagnose low T and determine its underlying cause:
1. Total serum testosterone test: This test measures the total amount of testosterone present in your bloodstream, including both free (active) testosterone and bound (unavailable) testosterone.
2. LH test: This test evaluates whether your pituitary gland is producing sufficient luteinizing hormone (LH), which is essential for testosterone production.
3. Prolactin test: Prolactin is another hormone produced by the pituitary gland. Elevated levels of prolactin can indicate pituitary gland abnormalities, which may affect testosterone levels.
Additionally, your doctor may recommend the following tests:
4. FSH test: Follicle-stimulating hormone (FSH) is produced by the pituitary gland and stimulates the testes to produce testosterone. Checking FSH levels helps ensure adequate pituitary function.
5. Thyroid hormone test: This test assesses levels of thyroid hormones, as abnormalities in thyroid function can disrupt testosterone production.
6. Estradiol hormone test: Estradiol is a type of estrogen (female sex hormone). This test may be performed if you have symptoms such as enlarged breasts, as elevated estradiol levels can affect testosterone balance.
7. MRI (Magnetic Resonance Imaging): An MRI scan may be recommended to identify any structural abnormalities or tumors in the pituitary gland that could be impacting hormone production.