TRT Glossary

Testosterone-Related Terms

  • Androgen: A class of hormones that includes testosterone, responsible for the development and maintenance of male characteristics.
  • Androgen Deficiency (AD): A broader term encompassing low testosterone levels. Symptoms of androgen deficiency, such as low libido or fatigue, can appear even with testosterone levels within the lower end of the normal range.
  • Bioavailable Testosterone: The portion of testosterone that is either free or loosely bound to albumin (a protein) and hence available to easily enter cells.
  • Dihydrotestosterone (DHT): A highly potent androgen derived from testosterone. It plays a significant role in prostate health, male pattern hair loss, and sex drive.
  • Estradiol (E2): The primary form of estrogen. In men, testosterone can be aromatized (converted) into estradiol. Maintaining a healthy balance between testosterone and estradiol is important on TRT.
  • Free Testosterone: The portion of testosterone that is not bound to proteins in the blood, readily available for the body’s use.
  • Hormone Replacement Therapy (HRT): The broad term for using supplemental hormones to address deficiencies. TRT is a specific type of HRT.
  • Hypogonadism: The medical condition of having abnormally low testosterone levels.
    • Primary Hypogonadism: Caused by a problem with the testicles themselves.
    • Secondary Hypogonadism: Caused by dysfunction in the pituitary gland or hypothalamus, which control testicular function.
  • Sex Hormone Binding Globulin (SHBG): A protein that tightly binds to testosterone in the blood, making it less bioavailable. Factors like age, thyroid function, and certain medications can influence SHBG levels.
  • Total Testosterone: The total amount of testosterone in the bloodstream, including free, loosely bound, and tightly bound testosterone.

TRT Forms and Medications

  • Aromatase Inhibitor (AI): Medication that blocks the aromatization of testosterone into estrogen, helping to maintain hormonal balance (e.g., Anastrozole, Letrozole, Exemestane).
  • Depot Injection: A long-acting injectable form of TRT in which the medication is suspended in an oily solution, gradually released over time.
  • Gonadotropin-Releasing Hormone (GnRH): A hormone released by the hypothalamus that signals the pituitary gland to produce LH and FSH. GnRH agonists and antagonists are sometimes used in advanced TRT protocols.
  • HCG (Human Chorionic Gonadotropin): A hormone that mimics the action of LH, stimulating the testicles to produce testosterone. It’s used with TRT to preserve fertility and prevent testicular atrophy.
  • Intramuscular (IM) Injection: Delivery of TRT via injection directly into a muscle.
  • Selective Estrogen Receptor Modulator (SERM): Medication that modulates estrogen’s effects on different tissues. They’re sometimes used with TRT to prevent gynecomastia or as an alternative to stimulate the body’s own testosterone production (e.g., Clomid, Tamoxifen, Raloxifene).
  • Subcutaneous (SubQ) Injection: Injection of medication into the fatty layer beneath the skin. Some forms of TRT can now be administered this way.
  • Testosterone Cypionate/Enanthate: Common long-acting testosterone esters used for injections with durations of 1-2 weeks.
  • Testosterone Gel/Patch: Transdermal forms of TRT, delivering testosterone through the skin for steady absorption.
  • Testosterone Pellets: Small pellets implanted under the skin, releasing testosterone slowly over 3-6 months.
  • Testosterone Propionate: A short-acting testosterone ester, sometimes requiring more frequent injections (every other day or three times per week).
  • Testosterone Sustanon 250: A blend of multiple testosterone esters with varying release times, designed for less frequent injections.
  • Testosterone Undecanoate: A very long-acting ester, allowing for injections every 10-12 weeks.

Other Relevant Terms

  • Baseline labs: Blood tests done before starting TRT to assess initial hormone levels, blood count, metabolic panel, etc.
  • Endocrinologist: A doctor specializing in hormone disorders, often involved in the diagnosis and management of TRT.
  • Fertility: The ability to reproduce. TRT can suppress sperm production and impact fertility.
  • Gynecomastia: Development of breast tissue in men, sometimes a side effect of TRT due to elevated estrogen.
  • Hematocrit: The percentage of red blood cells in your blood. TRT can increase hematocrit, sometimes requiring monitoring or therapeutic phlebotomy (blood donation).