Low Testosterone: Who Actually Has It, and Who Is Being Sold It
Fatigue, low mood, reduced libido and declining strength are real experiences, and an entire industry has grown around attributing them to low testosterone. Some of that is sound medicine, and a great deal of it is not.
What testosterone does
Beyond libido and erectile function, testosterone affects muscle mass and strength, bone density, red blood cell production, fat distribution, mood and energy, and sperm production.
Levels decline gradually with age, by roughly one per cent a year from the thirties. That gradual decline is normal ageing, and is different from hypogonadism, which is a clinical deficiency state.
Symptoms, divided by how specific they are
More specific to testosterone deficiency:
- Reduced sexual desire
- Fewer spontaneous morning erections
- Erectile dysfunction, though this has many other causes
- Reduced body and facial hair
- Small or shrinking testes
- Gynaecomastia
- Loss of height, or fracture with minor trauma
- Hot flushes
Non-specific, and shared with many other conditions:
- Fatigue
- Low mood
- Poor concentration
- Reduced muscle mass
- Increased body fat
- Poor sleep
The second list is where overdiagnosis happens, because those symptoms are far more commonly caused by sleep deprivation, sleep apnoea, depression, obesity, thyroid disease, anaemia, iron deficiency, diabetes, alcohol, medications or simply chronic stress.
How it should be diagnosed
Diagnosis requires both consistent symptoms and unequivocally low testosterone, confirmed properly.
Testing requirements:
- Morning sample, ideally between 7 and 11 am, because levels peak in the morning and fall substantially by the afternoon. An afternoon test is a common cause of spurious low results
- Fasting, since food lowers levels
- Two separate measurements on different days, since a single low value is often not reproduced
- Not during acute illness, which suppresses levels temporarily
If total testosterone is borderline, free testosterone or calculated free testosterone with sex hormone binding globulin is useful, because SHBG is raised by age, liver disease and hyperthyroidism, and lowered by obesity, insulin resistance and hypothyroidism, which distorts the total value.
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If deficiency is confirmed, the next step is to find out why. LH and FSH separate primary testicular failure, where they are high, from a pituitary or hypothalamic cause, where they are low or inappropriately normal. The second group needs further assessment including prolactin and iron studies, and sometimes pituitary imaging.
This matters: treating the testosterone without identifying a pituitary tumour or haemochromatosis is a missed diagnosis.
Reversible causes worth finding first
- Obesity, which lowers testosterone substantially, and weight loss raises it
- Obstructive sleep apnoea, which significantly suppresses testosterone, and which treatment improves
- Alcohol in excess
- Opioids, which are a potent and commonly overlooked cause
- Glucocorticoids
- Anabolic steroid use, past or present, which suppresses natural production, sometimes long term
- Poorly controlled diabetes
- Chronic illness and severe stress
Addressing these can resolve the deficiency without lifelong treatment, which is why they come before a prescription.
What treatment does and does not do
For men with genuine, confirmed hypogonadism, testosterone therapy reliably improves libido, erectile function in combination with other treatment, mood, bone density, lean mass and strength.
What it does not reliably do: transform energy in men with normal levels, improve cognition in a general sense, or deliver the effects promised by online clinics.
Important consequences of treatment:
- It suppresses sperm production, often substantially, and can cause infertility. Any man who may want children should discuss alternatives such as hCG or clomiphene before starting testosterone
- It raises haematocrit, which requires monitoring and sometimes dose reduction, because thickened blood raises clot risk
- It can worsen untreated sleep apnoea
- It causes testicular shrinkage
- It is generally lifelong once started, since natural production is suppressed
- Prostate cancer is a contraindication, and PSA is monitored during treatment
Monitoring, if treated
Testosterone level, haematocrit, PSA in men over 40, symptoms and side effects, typically at three and six months and then annually.
What to be sceptical of
- Online clinics that diagnose from a single afternoon blood test and a symptom questionnaire
- Treatment started without checking LH, FSH and prolactin
- Treatment started without screening for sleep apnoea in a man who snores
- Over-the-counter testosterone boosters, which have little evidence
- Treatment offered to men with normal levels for non-specific symptoms
The short version
Genuine testosterone deficiency needs symptoms plus two confirmed low morning fasting levels plus a search for the cause. Before accepting the diagnosis, make sure sleep apnoea, obesity, alcohol, opioids and depression have been looked at, and if you may want children, raise fertility before the first injection rather than after.