Patients typically come to us with one or more of the following symptoms that may indicate low testosterone:
- Low mood or depression
- Fatigue or low energy
- Poor sleep
- Low libido or erectile dysfunction
- Difficulty concentrating or “brain fog”
- Mood swings or irritability
- Decrease in muscle mass or strength
- Hot flushes
These symptoms alone do not confirm low testosterone, but they are strong indicators that testing may be appropriate.
Two Confirmatory Blood Tests
The British Society for Sexual Medicine (BSSM) clinical guidelines require two separate blood tests confirming low testosterone before starting TRT. This is because testosterone levels naturally fluctuate throughout the day, and readings can be temporarily affected by things like illness, poor sleep, alcohol intake, or even the time of day. Having two tests ensures there really is a consistent testosterone deficiency.
At least one of your two required tests needs to be an enhanced blood test. This is a much more comprehensive assessment than the finger-prick test, because it doesn’t just confirm your testosterone levels. It also looks at 39 key biomarkers. These include your full hormone profile, blood count, liver and kidney function, and other important health indicators. Since TRT can cause changes in these areas, it’s important for our clinicians to have this full picture. That way, a TRT doctor who has reviewed your case and clinical history can judge whether treatment is appropriate for you, and can take anything in your results into account before you start.
Treatment Thresholds
The levels we treat at depend on your age, because testosterone changes across age groups and starts to decline naturally from around 30.
- If you are 30 or over: total testosterone below 15 nmol/L, or free testosterone below 0.35 nmol/L. Either one on its own is enough.
- If you are under 30: total testosterone below 12 nmol/L and free testosterone below 0.225 nmol/L. The route is also different — please read the section below before ordering a test.
One exception worth knowing about. If your total testosterone is above 18 nmol/L you are not eligible for TRT, even if your free testosterone is below 0.35 nmol/L. This is the part that catches people out, because a low free testosterone reading on its own can look like it should qualify. Your doctor may still discuss other options with you, such as Tadalafil.
Our thresholds are deliberately wider than the BSSM guideline figures of 12 nmol/L total and 0.225 nmol/L free testosterone, and also reflect further international guidance, so that we can treat men who have symptoms but fall into the borderline range.
When your sample is taken matters
Testosterone is at its highest in the morning, so the time of day affects whether we can use a result.
- Under 30: all samples must be taken before midday. A later sample does not count and has to be repeated.
- 30 to 39: both readings must be taken before midday.
- 40 and over: at least one of your two readings must be taken before 2pm.
If you are under 30, please read this before ordering
Testosterone only begins to decline naturally from around the age of 30. In a younger man, a low result is more likely to have another underlying cause, and a doctor needs to understand that cause before deciding whether TRT is appropriate. So the route is not the same.
- If your first test comes back low, you will be asked to arrange an assessment with your GP or a specialist and upload the documents to us. You do not go straight to the enhanced blood test.
- What the doctor needs is normally a clinic letter signed by an endocrinologist, together with any relevant blood tests you have already had. It must be a readable medical report showing your full name and date of birth — a photo or PDF, never a screenshot.
- A doctor then reviews what you send. They may approve you to continue to the enhanced test, ask for more information, or conclude that TRT is not appropriate for you.
Two things to be aware of before you buy a test: completing the blood tests and having a consultation does not guarantee treatment if you are under 30, and the blood test is not refunded if the doctor concludes you are not eligible. If you are under 30 and unsure whether to order, please email us at trt@manual.co first and we will talk it through with you.
If treatment is not right for you, the doctor will explain why, and there may be other options worth discussing.
If your results are borderline
If your total testosterone is between 15 and 17 nmol/L and your free testosterone is 0.35 nmol/L or below, we will send you a retest kit free of charge. A single borderline reading is not enough to make a decision on, and a second test often gives a clearer picture.
Final Clinical Review
During the doctor consultation, your blood test results will be reviewed in detail, your symptoms and medical history discussed, all treatment options and associated costs explained, and any clinical questions addressed so you feel fully informed and confident about the next steps.
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