Low Testosterone Blood Test: What Do the Results Mean and What Comes Next?

A low testosterone blood test result means the level in that sample was below the lab's reference range. On its own, it does not confirm low testosterone (male hypogonadism). The Endocrine Society says the diagnosis needs symptoms plus consistently low levels, confirmed by repeating the test in the morning.

This guide is for adult men looking at a first or borderline low result. It explains how clinicians usually confirm a result and look for a cause. It does not cover treatment, doses or products, and it cannot tell you whether your own result is significant.

Some symptoms should not wait for a repeat hormone test. NHS guidance says to go to an emergency department or call emergency services for sudden, severe pain in a testicle, testicle pain with nausea, vomiting or stomach pain, or testicle pain lasting more than an hour or continuing at rest. Do not drive yourself.

The NHS advises an urgent appointment with your doctor for a new lump, swelling, change in shape or feel, or one testicle becoming larger than the other. Healthdirect also advises seeing a doctor if you have symptoms that suggest low testosterone or are having difficulty conceiving.

Testosterone levels change through the day and from day to day. MedlinePlus explains that levels are typically highest in the morning, which is why samples are usually taken then. The Endocrine Society guideline recommends measuring total testosterone on two separate mornings, while fasting, and notes that a meaningful share of men with a first low result have a normal level when retested.

Short-term factors can also lower a reading. The guideline advises against testing during or soon after an acute illness, or during short-term use of medicines that suppress testosterone, such as opioids. Cleveland Clinic notes that illness can temporarily lower levels, so tell the clinician if you were unwell. MedlinePlus says some medicines may need to be paused before a test, but only on a clinician's advice.

There is no single number for everyone. Labs use different methods and reference ranges, so check the range printed beside your result. The Endocrine Society's patient information gives a rough adult male range of 300 to 1,000 ng/dL, depending on age and lab, and Cleveland Clinic says levels below 300 ng/dL are generally considered low in adults. Some countries report testosterone in nmol/L, so compare like with like.

MedlinePlus notes that levels normally fall with age and that a testosterone test alone cannot diagnose any condition. The result is read together with your age, symptoms, examination and other tests. A result just below the range means something different from one far below it, so ask how your clinician reads your specific number.

Most testosterone in the blood is bound to proteins, mainly sex hormone-binding globulin (SHBG) and albumin, according to MedlinePlus. A standard test measures total testosterone, which includes bound and unbound forms. Free testosterone is the small unbound part.

When SHBG is unusually low or high, total testosterone may not reflect what is available to the body. The Endocrine Society guideline lists obesity and diabetes among conditions that lower SHBG, and ageing, liver disease and an overactive thyroid among those that raise it. When total testosterone is near the lower limit, or SHBG is likely to be altered, the guideline suggests measuring free testosterone with a reliable lab method or calculating it from total testosterone, SHBG and albumin.

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) come from the pituitary gland. MedlinePlus explains that in men, LH signals the testes to make testosterone. The Endocrine Society recommends measuring LH and FSH once low testosterone is confirmed, to tell apart the two main types.

• Primary hypogonadism: the problem is in the testes. They do not make enough testosterone despite the brain's signal, so LH is often high.
• Secondary hypogonadism: the problem is in the pituitary gland or hypothalamus. The signal itself is too low, so LH may be low or not as high as expected.
• Further tests may follow, depending on the pattern. Sources mention prolactin, iron studies, genetic testing and sometimes a pituitary MRI.

Cleveland Clinic and the Endocrine Society list many possible causes. These include injury, infection or treatment affecting the testes, such as chemotherapy or radiation; pituitary disease or high prolactin; obesity, type 2 diabetes, sleep apnoea, and liver or kidney disease; some medicines, including opioids and corticosteroids; anabolic steroid use; and genetic conditions such as Klinefelter syndrome.

Healthdirect notes that the gradual age-related decline seen in healthy older men is generally not considered a medical concern. The Endocrine Society does not recommend routine testosterone screening in men without symptoms.

Bring copies of each result with the date, time of the sample, units and reference range, plus a list of your medicines and supplements.

• Was my sample taken in the morning, and was I fasting?
• Could a recent illness, medicine or other factor have lowered this result?
• When should the test be repeated, and how should I prepare for it?
• Is my SHBG likely to be high or low, and does free testosterone need to be checked?
• If the low level is confirmed, will LH and FSH be measured, and what would the results change?
• Which of my symptoms fit low testosterone, and what else could explain them?

On SameCase, patients and verified doctors share de-identified cases. Seeing how others recorded the timing of their tests, their SHBG or LH results and their symptoms can help you organise your own records and write down clear questions before an appointment.

Similar cases cannot interpret your results or tell you whether you need treatment. Use them to prepare questions, and leave the assessment to the clinician who knows your full history.