The GP’s role
GPs are generally the first point of contact for men with symptoms of androgen deficiency.
GPs are relied upon for clinical and laboratory examinations, appropriate referral, and ongoing patient management.
Patient referral to an endocrinologist, urologist or sexual health specialist is required for PBS-subsidised testosterone prescriptions.
Overview
Androgen deficiency is a syndrome caused by poor testicular function (hypogonadism), resulting from either primary (testicular) or secondary (hypothalamic-pituitary) disease, and is characterised by a low testosterone level accompanied by signs and symptoms.
It is estimated that approximately 5 in 1000 men have androgen deficiency warranting treatment with testosterone.
A low testosterone level alone does not constitute androgen deficiency, and neither does the observed age-related decline in testosterone (of approximately 1% annually).
Androgen deficiency may have subtle effects on health and wellbeing, which can make diagnosis challenging. Untreated androgen deficiency has detrimental effects on body composition and bone health.
Causes
Diagnosis
Clinical examination and assessment
Laboratory examinations and assessment
*Accurate serum testosterone measurements require mass spectrometry. Values from immunoassays are less accurate, and there is significant variability between laboratories and methods, and in reference intervals.
At least two measurements of serum testosterone, LH and FSH (from fasting, morning samples collected on separate days) are required for diagnosis of androgen deficiency.
PBS criteria require androgen deficiency to be confirmed by serum testosterone below 6 nmol/l, or 6-15 nmol/l with LH 1.5 times higher than reference range (or above 14 IU/l).
Management
Testosterone replacement therapy (TRT)
TRT is aimed at relief of symptoms and signs of androgen deficiency, using convenient and effective (intramuscular or transdermal) testosterone preparations.
| T formulation | Usual (starting) dosage | Dosage range |
|---|---|---|
| Injections (IM) | ||
| Testosterone undecanoate | 1000mg twice at 6-week interval, followed by 12-weekly | 1000mg at 8-16-week interval |
| Combined testosterone propionate Testosterone phenylpropionate Testosterone isocaproate Testosterone decanoate* Testosterone enantate* | 250mg every 3 weeks | 250mg at 10-21-day intervals |
| Transdermal gel | ||
| Testosterone | 50mg daily | 25-100mg daily |
| Transdermal cream | ||
| Testosterone# | 100mg daily applied to upper body 25mg daily applied to scrotum | Up to 200mg daily (to torso) Up to 50mg daily (to scrotum) |
| Transdermal patch | ||
| Testosterone | 5mg applied nightly | 2.5-5mg nightly |
| Oral undecanoate | ||
| Testosterone undecanoate* | 80mg 2-3 times daily | 80-240mg daily |
Exogenous testosterone suppresses spermatogenesis in eugonadal men and should NOT be commenced in men desiring fertility. Men with secondary hypogonadism who wish to preserve fertility should be managed using gonadotrophin therapy.
Athletes may require a Therapeutic Use Exemption prior to commencement of TRT.
Monitoring TRT
Alleviation of a patient’s leading symptom is the best clinical measure of effective management.
Blood sampling for serum testosterone, LH and FSH measurement should be timed to allow estimation of steady-state testosterone levels, which is feasible by sampling during the trough (immediately before next dose) for men using injectable and transdermal preparations.
Timing of sampling for accurate measurement in men taking oral testosterone is more difficult.
Referral
PBS-subsidised prescription of TRT requires treatment by, or in consultation with, a specialist endocrinologist, urologist or registered member of the Australian Chapter of Sexual Health Medicine.
Management of paediatric patients must be overseen by a specialist paediatric endocrinologist or general paediatrician.
Long-term management of androgen deficiency is best planned in consultation with a specialist endocrinologist.
Refer to a fertility specialist as needed.
Refer males aged > 14.5 years with delayed puberty to a paediatric endocrinologist.
Clinical review
Dr Ie-Wen Sim, University of Melbourne
