Before undergoing testosterone replacement therapy (TRT), it's vital to conduct a number of blood tests in order to create a baseline from which to assess the progression of the therapy, to check for hypogonadism (low testosterone) and assess overall health. Baseline tests are also conducted during TRT, ensuring that doctors can adjust the dose and correct side effects before they become an issue.

This is what the test will measure:

Total Testosterone

Testosterone plays a key part in sex hormones in males and has an important role in the production of sperm, muscle size, bone mass, strength, and libido. It is also considered the major promoter of muscle growth and subsequent increase in muscle strength in response to resistance training in men.

It is normal for men to experience a gradual decline in testosterone levels after the age of 30, but low testosterone levels may mean you are experiencing several other hormonal imbalances that mean you are not feeling your best. 

Your total testosterone level includes both bound and unbound fractions of testosterone. 

Free Testosterone

Free testosterone is the unbound form of testosterone in your body.

It is a small but important component of the total testosterone in a man’s body and is responsible for key cellular functions such as cell replication.

DHEA-s

DHEA-s is a hormone produced by the adrenal glands that helps to make other hormones, like testosterone and estrogen, and its levels are an indicator of adrenal function and exposure to stressors. Its production is highest in the late teens to early 20s and declines gradually with age.

Follicle-Stimulating Hormone (FSH): In men, a follicle-stimulating hormone (FSH) test may be done to evaluate a low sperm count, assess hypogonadism or assess testicular dysfunction.

Luteinizing hormone (LH)

LH is a hormone produced by the anterior pituitary that is essential for reproduction in both men and women. LH stimulates the production of testosterone and, therefore, measuring LH levels is helpful for the clinical assessment of infertility. Low LH levels in men can result in hypogonadism and insufficient sperm production.

Prostate-Specific Antigen Test (PSA)

Detecting certain types of prostate cancer early can be critical. Elevated PSA results may reveal prostate cancer that's likely to spread to other parts of your body (metastasize), or they may reveal a quick-growing cancer that's likely to cause other problems. Catching it early provides the best outcomes.

SHBG

SHBG (sex hormone binding globulin) controls how much testosterone is being delivered to the body's tissues. SHBG levels can show if there is too much or too little testosterone being used by the body.

Hematocrit

Blood is made up of red blood cells, white blood cells and platelets, suspended in plasma. Together, those comprise about 45% of the volume of our blood, but the specific percentages of each can vary. Hematocrit is the percentage by volume of red cells in your blood.

Because the purpose of red blood cells is to transfer oxygen from the lungs to body tissues, a blood sample's hematocrit can be an indicator of its capability of delivering oxygen. If you have too many red blood cells (high hematocrit), your blood gets thicker and the risk of heart attack or stroke escalates considerably.

Hematocrit levels that are too high or too low can indicate a blood disorder, an elevated risk of dementia, dehydration or other medical conditions. An abnormally low hematocrit may suggest anemia.

For those using TRT, it’s particularly important to have your hematocrit levels checked regularly.

Estradiol

An estradiol test measures the amount of the hormone estradiol in your blood. 

Estradiol, the predominant form of estrogen, also plays a critical role in male sexual function. Estradiol in men is essential for modulating libido, erectile function, and spermatogenesis