- Low level (AUA)
- Below 300 ng/dL
- How it is confirmed
- Blood drawn before noon, on two different days
- Once stable on treatment
- Labs every 6 to 12 months
What testosterone does
Testosterone is the male sex hormone, and it is made in the testicles. It matters for normal male sexual development and function. During puberty it helps boys develop body and facial hair, a deeper voice and muscle strength. Men also need testosterone to make sperm.
Testosterone levels generally go down with age, so older men tend to have lower levels. When the level is too low, it is called testosterone deficiency (TD) or low testosterone (low T). The American Urological Association (AUA) defines a low blood testosterone level as less than 300 nanograms per deciliter (ng/dL).
Symptoms
- Low sex drive
- Tiredness
- Less lean muscle
- Irritability
- Erectile dysfunction
- Depression
- Poor memory or concentration
These symptoms can have many other causes too, which is why the blood tests matter.
How common is it?
It is hard to know exactly how many men have TD. Data suggest that overall about 2.1% of men (about 2 in every 100) may have it. As few as 1% of younger men may have TD, while as many as 50% of men over 80 may have it.
TD is more common in men who have diabetes or are overweight. In one research study, 30% of overweight men had low T, compared with 6.4% of men at a normal weight. The same study found diabetes to be a risk factor. In another study, 24.5% of men with diabetes had low T, compared with 12.6% of men without diabetes.
What causes it
- Aging
- Obesity
- Metabolic syndrome (high blood pressure, high blood sugar, unhealthy cholesterol levels and belly fat)
- Injury to the testicles
- Removal of the testicles because of cancer
- Chemotherapy or radiation
- Disease of the pituitary gland, the gland in the brain that signals the testicles to make testosterone
- Infection
- Autoimmune disease, when the body makes antibodies that attack its own cells
- Medicines such as antidepressants and narcotic pain medicines
- HIV/AIDS
How it is tested
Testosterone levels are highest in the morning and drop later in the day. So the key test, total testosterone, is done on blood taken before noon, on two different occasions. Dr. Su may also order other blood tests to find the cause and to make sure treatment is safe for you.
| Test | Why it is checked |
|---|---|
| Total testosterone (twice, before noon) | Confirms whether your level is truly low |
| Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) | Signals from the pituitary gland; they help show whether the problem starts in the testicles or in the brain |
| Prolactin | A pituitary hormone that can lower testosterone when it is high |
| Estradiol | A form of estrogen that men also make; it can rise during testosterone treatment |
| Hemoglobin | A starting point for your blood count, since testosterone treatment can raise it |
| HbA1c | Checks for diabetes, which is linked to low T |
If fertility matters to you, you may also need a semen test.
Ways to take testosterone
There are five main ways to take testosterone therapy (TT). You can choose the one that fits your life best. In some cases, your insurance plan decides the order in which options are tried.
On the skin
Transdermal gels, creams, liquids and patches, applied to the skin.
Injections
Short-acting and long-acting options. Examples include Xyosted and testosterone cypionate.
Oral or buccal
Taken by mouth. Buccal testosterone is held against the gum or inner cheek.
In the nose
A gel pumped into each nostril, usually three times a day (Natesto).
Pellets
Small pellets placed under the skin of the upper hip or buttocks, in the office with local anesthesia. They dissolve slowly and release testosterone over about 3 to 6 months, depending on the number of pellets.
Medicines that help your body make more testosterone
Some medicines raise testosterone by prompting your own testicles to make more. Each can be used alone or together with testosterone therapy.
- Clomiphene citrate is a selective estrogen receptor modulator. It works through the body’s feedback system, raising LH and FSH so the testicles make more testosterone and sperm.
- hCG (human chorionic gonadotropin) acts like LH. It stimulates the Leydig cells in the testicles to make more testosterone.
Side effects and safety
- Gels and liquids can cause redness where they are applied. Gels, creams and liquids can also rub off onto other people, so cover the area and wash your hands after applying.
- Patches can cause itching and a rash around the patch. A very small number of patients report back pain.
- Short-acting injections can cause a reaction where the shot is given. Some people have had serious allergic reactions to the long-acting injection.
- Pellets can cause swelling, pain and bruising and, rarely, a hematoma (clotted blood under the skin).
Testosterone therapy raises the risk of erythrocytosis, an abnormal rise in hemoglobin and hematocrit, which means too many red blood cells in the blood. Your blood count is checked during treatment for this reason.
Planning to have children? Testosterone therapy can interrupt normal sperm production. You should not take it if you plan to have children soon. If you are being treated for low T, Dr. Su may suggest added treatment to support sperm production.
There is no evidence linking testosterone therapy to prostate cancer. There is no strong evidence linking it to an increase in blood clots in the veins. At this time, there is no strong evidence that it either increases or decreases the risk of heart attack or stroke. Even so, while you are on testosterone therapy, get emergency care right away if you have signs of a stroke or heart attack, and let Dr. Su know.
What treatment can and cannot do
Every person is different, and each body responds differently to treatment. Testosterone therapy may help erections, low sex drive, bone density, anemia (a low blood count), lean muscle mass and symptoms of depression. However, there is no strong evidence that it improves memory, measures of diabetes, energy, tiredness, cholesterol levels or quality of life.
You will need regular checkups to make sure your testosterone level stays in the normal range. Once you are stable on treatment, your testosterone and certain other lab tests are checked every 6 to 12 months.
Questions patients ask
Why does my blood test have to be in the morning?
Testosterone is highest in the morning and drops later in the day. A test taken in the afternoon can look low when your level is actually normal, so the test is done before noon, on two different days.
Can I take testosterone if I want to have children?
Not if you plan to have children soon, because testosterone therapy can interrupt sperm production. Medicines such as clomiphene citrate or hCG, which help your own testicles make more testosterone, may be options. Talk with Dr. Su before starting any treatment.
Does testosterone therapy cause prostate cancer?
There is no evidence linking testosterone therapy to prostate cancer. You will still have regular checkups and lab tests while you are on treatment.
Which form of testosterone is best?
There is no single best form. Some men prefer a daily gel, others an injection every few weeks or pellets a few times a year. Dr. Su will go through the choices with you, and your insurance plan may decide which one you try first.