How is Low Testosterone Diagnosed?

Although many symptoms may be tied to Low Testosterone (Low-T), total blood testosterone level is the most important measure of testosterone deficiency. To make a diagnosis, your doctor will use other specific signs and symptoms in addition to your testosterone blood level.

At your medical visit, your health history will be taken, and the doctor will do an exam and look for some of the signs and symptoms mentioned in this article.

Health History 

Your doctor may ask you about:

  • Headache, visual field change (possible symptoms of brain mass such as a pituitary tumor) 
  • How you developed at puberty 
  • History of head trauma 
  • Cranial (head) surgery/brain tumor or cranial irradiation 
  • Anosmia (loss of ability to smell) 
  • History of infection in your testicles 
  • Injury to your testicles
  • Mumps after puberty
  • Past or present use of anabolic steroids 
  • Use of opiates 
  • Use of glucocorticoids (medicines, such as cortisone, used to treat inflammation) 
  • History of chemotherapy or irradiation 
  • Family history of diseases linked to Low-T
  • History of stroke or heart attack
  • History of unexplained anemia 

Physical Examination

Your doctor will check for the following:

  • BMI or waist circumference for obesity 
  • Metabolic syndrome. These are symptoms (seen together) of increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels 
  • Hair pattern, amount, and location 
  • Gynecomastia (enlarged breasts) 
  • Whether testicles are present and their size 
  • Prostate size and any abnormalities 


Your doctor may order these blood tests:

  • Total testosterone level. This test should be done at two different times on samples taken before noon. Testosterone levels are lower later in the day. If you are ill, the doctor will wait until you are not sick because your illness may cause a false result.
  • Luteinizing hormone (LH). This test is done to help find the cause of a Low-T level. This hormone controls how you make testosterone. Abnormal levels may mean a pituitary gland problem.
  • Blood prolactin level. If your prolactin level is high, your doctor may repeat the blood test to make sure there is no error. High prolactin levels also may be a sign of pituitary problems or tumors.
  • Blood hemoglobin or Hgb. Before doing this test, your doctor will look for other reasons for low Hgb such as climate level (like climate altitude), sleep apnea, or tobacco smoking.

The following also may be done to help with further diagnosis:

  • Follicle stimulating hormone (FSH). This test is to check for sperm-making function if you want to have children. You may also need to have semen tests. These tests will be done before any hormone therapy.
  • Estradiol hormone test is done if there are breast symptoms.
  • HbA1C blood test may be done for diabetes.
  • MRI (magnetic resonance imaging) of the pituitary gland 
  • Bone density tests.
  • Karyotype (Chromosome tests).

You may hear about free testosterone or bioavailable tests for testosterone. These are not the same as total testosterone level tests. Ask your doctor about the differences and if you need these tests.