Reference
Low testosterone & TRT glossary
Every hormone, test, and treatment that comes up in an Australian low-testosterone work-up — defined in plain English.
Jump to: Total testosterone · Free testosterone · SHBG (Sex Hormone Binding Globulin) · LH (Luteinising Hormone) · FSH (Follicle Stimulating Hormone) · Hypogonadism · Primary hypogonadism · Secondary hypogonadism · TRT (Testosterone Replacement Therapy) · Injection treatment · Topical treatment · ADAM (Androgen Deficiency in Aging Males) · PBS (Pharmaceutical Benefits Scheme) · hCG (Human Chorionic Gonadotropin)
Total testosterone
The sum of all testosterone circulating in the blood — both protein-bound and free. The standard first-line measurement in an Australian hormone work-up. Normal adult male reference range is approximately 8–30 nmol/L.
Free testosterone
The small fraction of total testosterone not bound to SHBG or albumin, and therefore biologically active. Usually calculated rather than measured directly. Especially useful when SHBG is abnormal.
SHBG (Sex Hormone Binding Globulin)
The liver-produced protein that binds testosterone in the bloodstream. High SHBG can make total testosterone look normal while free testosterone is low; low SHBG (common in obesity and insulin resistance) does the opposite.
LH (Luteinising Hormone)
A pituitary hormone that signals the testes to produce testosterone. High LH with low testosterone indicates a testicular cause (primary hypogonadism); low LH with low testosterone indicates a pituitary or hypothalamic cause (secondary hypogonadism).
FSH (Follicle Stimulating Hormone)
A pituitary hormone that supports sperm production. Measured alongside LH to characterise the cause of low testosterone and to assess fertility.
Hypogonadism
The medical term for clinically low testosterone with associated symptoms. Diagnosis requires two morning blood tests showing low total testosterone plus consistent symptoms.
Primary hypogonadism
Low testosterone caused by a problem with the testes themselves. Characterised by low testosterone with high LH and FSH.
Secondary hypogonadism
Low testosterone caused by a problem at the pituitary gland or hypothalamus. Characterised by low testosterone with low or inappropriately normal LH and FSH.
TRT (Testosterone Replacement Therapy)
Prescribed testosterone given as injections, gel, cream or patches that a doctor may consider for men with diagnosed hypogonadism. PBS-subsidised in Australia for men who meet eligibility criteria.
Injection treatment
A method of delivering prescribed treatment by injection. Frequency, suitability and monitoring are decided by a doctor.
Topical treatment
Treatment applied to the skin. Some prescribed treatments can transfer to others through skin contact; follow the safety instructions supplied by your doctor or pharmacist.
ADAM (Androgen Deficiency in Aging Males)
A 10-question validated symptom screen used to identify men who may have low testosterone and benefit from formal testing. A positive screen is not a diagnosis — confirmation requires two morning blood tests.
PBS (Pharmaceutical Benefits Scheme)
The Australian government scheme that subsidises the cost of prescription medications. PBS-listed testosterone reduces the out-of-pocket cost of TRT to the standard co-payment per script.
hCG (Human Chorionic Gonadotropin)
A hormone that mimics LH and stimulates the testes to produce testosterone. Sometimes used instead of or alongside TRT, particularly to preserve fertility in younger men.
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*Blood tests may be bulk billed where eligible, subject to doctor assessment and clinical indication.