Low testosterone levels: symptoms and when to test

Testosterone is the main male sex hormone. It plays a role in muscle and bone mass, sperm production, sex drive and mood. Levels decline naturally and gradually with age, but a symptomatic drop isn’t something you simply have to accept — it can be investigated.

Symptoms that raise suspicion

They are non-specific, and that’s the problem: they’re easily put down to stress or age. The most common are reduced sex drive, erectile dysfunction, persistent fatigue, loss of muscle mass, increased abdominal fat, and changes in mood or concentration.

How it’s measured

With a blood test. Two important details:

Timing matters

Testosterone follows a daily rhythm and is highest in the morning, so the blood sample should be taken first thing, ideally while fasting.

One result isn’t enough

If it comes back low, it’s confirmed with a second measurement before considering anything further.

What is checked next

Once confirmed, the work-up is completed with other hormone tests to establish whether the cause lies in the testicle or the pituitary gland.

What to do with the result

An isolated low value, with no symptoms, is not in itself an indication for treatment. And conversely, symptoms with normal testosterone mean another cause needs to be found. Replacement therapy, when indicated, requires ruling out contraindications first and regular follow-up, including monitoring of the prostate.

In short: testosterone is measured when there are symptoms, confirmed before treating, and always treated under medical supervision.