If you have received a clinical diagnosis of hypogonadism (low testosterone), the next critical step is determining the root cause. Low T is not a diagnosis in itself; it’s a symptom of a failure somewhere in the Hypothalamic-Pituitary-Gonadal (HPG) Axis.
Understanding whether you have Primary or Secondary Hypogonadism dictates your long-term health monitoring and which therapies may be most appropriate.
For an overview of the legal framework and treatment options in Canada, refer to The Ultimate Canadian TRT Guide.
The HPG axis is the hormonal feedback loop that regulates testosterone production. Think of it as a three-part system:
When testosterone levels are low, the brain releases more GnRH and the pituitary releases more LH/FSH (a signal to boost production).
Primary hypogonadism, or Testicular Failure, occurs when the problem lies directly in the testes. They are unable to produce adequate testosterone, even though the brain is sending strong signals.
Cause | Description | Example |
Genetic | Conditions affecting testicular development or function from birth. | Klinefelter Syndrome (XXY chromosome), Cryptorchidism (undescended testes). |
Physical Trauma | Direct injury to the testes that causes permanent damage to the Leydig cells. | Sports injury, accident, or testicular torsion. |
Infection/Disease | Damage caused by viral infections or post-inflammatory atrophy. | Mumps orchitis (inflammation after mumps), HIV infection. |
Toxicity | Damage caused by medical treatments or environmental factors. | Chemotherapy, radiation therapy, or severe alcohol abuse. |
Secondary hypogonadism, or Central Hypogonadism, occurs when the testes are physically capable of producing testosterone, but they are not receiving the necessary hormonal signal from the pituitary or the hypothalamus.
Cause | Description | Clinical Impact |
Obesity & Age | Adipose tissue increases Aromatase activity, converting T to E2, which signals the pituitary to reduce LH\FSH production. | This is the most common cause of “late-onset” low T in men. |
Pituitary Adenoma | Non-cancerous tumor on the pituitary gland, disrupting LH\FSH release. | Requires specific brain imaging (MRI) for diagnosis. |
Chronic Opioid Use | Can suppress GnRH release from the hypothalamus, shutting down the entire axis. | Often reversible upon cessation of the medication. |
Chronic Illness | Severe stress, chronic pain, or systemic disease can suppress central hormonal signalling. | Kidney failure, severe inflammatory diseases. |
Medications | Glucocorticoids (steroids) and certain mental health medications. | Requires review of all current prescriptions. |
Kallmann Syndrome | A rare genetic condition where the hypothalamus fails to release GnRH. | Associated with an impaired sense of smell (Anosmia). |
Identifying the type of hypogonadism is vital, especially if you are concerned about maintaining fertility.
Always discuss your LH and FSH results with your Canadian physician to determine the precise location of the failure before starting any hormonal therapy.