Testosterone, Serum (Mass Concentration)

A testosterone test measures the amount of testosterone, an important sex hormone, in your blood. Your doctor may order this test to help explain symptoms such as low energy, reduced sex drive, erectile dysfunction, infertility, or mood changes. It can also help evaluate excess hair growth, acne, irregular menstrual periods, or early or delayed puberty in children and teens.

Doctors may order this test to diagnose or monitor conditions related to hormone imbalances, such as low or high testosterone levels. It can also help evaluate symptoms like low libido, fatigue, or changes in body hair. Sometimes, it’s used in fertility evaluations or before certain surgeries.

Your doctor will let you know if any preparation is needed. Testosterone levels are usually highest in the morning, so you may be asked to have your blood drawn early in the day. Tell your doctor about all medicines, vitamins, and supplements you take, because some drugs, such as steroids or hormone therapy, can affect your results. You can usually eat and drink normally unless told otherwise.

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Wear comfortable clothing and bring any medications you’re currently taking.

A health care professional will wrap an elastic band around your upper arm, clean the skin, and insert a small needle into a vein, usually in your arm. A small amount of blood is collected into a tube, and the needle is then removed. The whole process takes only a few minutes, and you may feel a brief sting when the needle goes in. A small bandage is placed over the site afterward.

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

Your results are compared with normal reference ranges that vary by age and sex. In men, low levels may suggest a problem with the testicles or the pituitary gland, while high levels can occur with supplements or certain tumors. In women, high levels may point to polycystic ovary syndrome (PCOS) or other hormonal conditions. Your doctor will explain what your specific numbers mean for your overall health.

Results are typically reported in nanograms per deciliter (ng/dL) or other standardized units. Your doctor will compare these results to your individual reference range and medical history to determine if further action is needed.