Useful resources for further reading:
European Male Aging Study followed over 3,000 men and put the prevalence of secondary TD at around 12%, with rates climbing alongside age, obesity, and comorbidities.
The risk factor profile:
Type 2 diabetes
Metabolic syndrome
CKD, atrial fibrillation
Obstructive sleep apnoea
Chronic heart failure
Long-term opioid use
Antipsychotics, anticonvulsants, or finasterid.
The symptoms aren't dramatic, which is part of why it gets missed:
Reduced libido
Erectile dysfunction
Fatigue
Low mood
Poor concentration
Reduced muscle mass
Central weight
None of those are specific to TD in isolation, but the BSSM guidelines make the point well: the more symptoms present together alongside a low testosterone, the more confident you can be that you're looking at genuine hypogonadism. If a man has consistent symptoms and any of those risk factors, routine screening (including a blood testosterone) is warranted.
Measure total testosterone (TT) on a morning sample between 7 and 11am, and repeat it at least once, at least four weeks later
A single measurement is too easily confounded by stress, illness, or lab variation.
A TT below 8 nmol/L confirms TD.
Between 8 and 12 nmol/L is borderline and needs SHBG to calculate free testosterone.
This is worth noting for men with pre-diabetes: borderline levels up to 14 nmol/L are clinically significant
Round off with LH and FSH to classify primary versus secondary TD,
Measure prolactin if pituitary pathology is on your radar
Plus the standard thyroid/HbA1c/lipid screen.
Where TD is confirmed and there are no contraindications — prostate cancer, male breast cancer, desire for children, haematocrit above 54%, or severe heart failure, a trial of TRT is indicated.
Transdermal gels are first-line for most patients: stable levels, adjustable dosing, and easy to withdraw if needed.¹ Intramuscular injections are a well-evidenced alternative, particularly testosterone undecanoate if less frequent dosing is preferable. Before prescribing, check your local ICB formulary, testosterone sits under shared care protocols in many areas, and the requirements vary.
Two things are always worth doing first, regardless of where you land on treatment.
Address lifestyle — the relationship between obesity and low testosterone is strong, and meaningful weight loss can move the needle on TT without any medication.
Review the medication list carefully. Long-term opioids and TD symptoms in the same patient are rarely a coincidence.
These articles report on published research. It does not constitute medical advice.
