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Most men with low testosterone don't know they have it. The symptoms - fatigue, low mood, brain fog, poor sleep, reduced libido, slow recovery from training - are common enough that they get blamed on stress, age, or "just getting older."
A blood test takes 10 minutes and tells you whether your hormones are actually the issue. Here's how to get it done properly.
I went through the NHS route first. My GP said my testosterone was "normal" at 11.2 nmol/L. I felt terrible. A private test with a full panel told a different story - my free testosterone was low, my SHBG was elevated, and my vitamin D was deficient. None of that came up in the NHS result. That's when I started paying attention.
The Problem With NHS Testosterone Testing
What each blood test service actually checks
Tap a marker to see why it matters. Tap a service to highlight its panel.
Panels shown are indicative — services offer multiple tiers. Always verify current panel contents before ordering.
The NHS tests testosterone. Singular. One marker, one measurement, often taken at the wrong time of day, with a reference range that flags deficiency only at the very bottom of the population distribution.
What the NHS typically does:
- Tests total testosterone only
- Uses a deficiency threshold of under 8-10 nmol/L (NICE guidelines) - clinically symptomatic men often present at 12-15 nmol/L
- Tests at whatever time of day the appointment falls
- Doesn't test free testosterone, SHBG, LH, FSH, or oestradiol as standard
- Will often tell you you're "normal" when you're in the lower quartile for your age
This isn't a criticism of GPs - it's a resource constraint. A comprehensive hormone panel costs more than an NHS budget allows per patient, and without symptoms severe enough to trigger secondary care, you won't get one.
Never test testosterone after midday. Testosterone follows a diurnal rhythm - it peaks between 7-10am and declines throughout the day. An afternoon test can show results 20-30% lower than a morning test in the same person. Always test fasting, between 7-10am.
What a Proper Testosterone Test Should Include
A meaningful assessment of testosterone status requires more than total testosterone. These are the markers that give you the full picture:
Tier 1 - Essential:
- Total testosterone - the headline number
- Free testosterone (calculated) - the biologically active fraction; often more relevant than total T
- SHBG (sex hormone-binding globulin) - binds testosterone; high SHBG = lower free T even with normal total T
- LH (luteinising hormone) - tells you whether low T is a signalling problem or a production problem
- FSH (follicle-stimulating hormone) - pituitary health marker
Tier 2 - Important:
- Oestradiol (E2) - testosterone converts to oestradiol; too high or too low causes problems
- Prolactin - elevated prolactin suppresses testosterone; often missed
- Thyroid (TSH, Free T3, Free T4) - hypothyroidism mimics low testosterone almost perfectly
Tier 3 - Useful context:
- Vitamin D (25-OH) - cofactor for testosterone production
- Full blood count - rules out anaemia causing fatigue
- HbA1c - insulin resistance suppresses testosterone
- Liver function - affects hormone clearance
Option 1: Go Through Your GP
When it makes sense: You have clear symptoms of hypogonadism (very low libido, erectile dysfunction, loss of body hair, significant fatigue) and want NHS follow-up including endocrinology referral if needed.
How to approach it:
- Book a morning appointment specifically - explain you want a testosterone test and have read it should be done fasting in the morning
- List your symptoms clearly before the appointment - fatigue, low mood, reduced libido, poor recovery. Written symptoms carry more weight than verbal
- Ask for total testosterone, SHBG, and LH as a minimum
- If your result comes back "normal" but you're still symptomatic, ask for the actual number - not just "normal". Know that BSSM guidelines recommend treating symptoms below 12 nmol/L, not just below 8
The limitation: You may wait 3-6 weeks for an appointment, the test may not be done at the right time, and the panel is usually incomplete.
Option 2: Private Home Test Kit
When it makes sense: You want comprehensive results quickly, don't want to involve your GP, or your GP has dismissed your concerns.
How it works: Kit arrives in the post (usually next day). Finger-prick sample collected at home between 7-9am, fasting. Returned in pre-paid packaging. Results in 24-48 hours via app or email. Doctor's report included.
Best options:
Option 3: Private Venous Blood Draw
When it makes sense: You're on TRT or use topical testosterone. You want the most accurate results. You've had inconsistent finger-prick results.
Finger-prick tests are accurate for most markers in most men. But if you use testosterone gel, cream, or patches, skin contamination of a finger-prick sample can significantly skew results. Venous blood drawn from the arm - away from any application sites - eliminates this risk.
How to get it:
- Medichecks and Forth both offer venous draws at partner clinics (Spire, Nuffield, etc.) for an additional fee (~£35-45)
- Lola Health sends a registered phlebotomist to your home - best option if you can't travel to a clinic
Understanding Your Results
Total Testosterone Reference Ranges (UK, nmol/L)
| Range | Classification | What It Means | |-------|---------------|---------------| | Under 8 nmol/L | Hypogonadal | NHS threshold for treatment | | 8-12 nmol/L | Low-normal | Symptomatic men often treated by BSSM-trained clinicians | | 12-15 nmol/L | Grey zone | Free T and symptoms matter here | | 15-25 nmol/L | Normal | Most adult men | | 25-35 nmol/L | Optimal | Well-optimised | | Above 35 nmol/L | High | Above range without TRT - investigate |
The grey zone (8-15 nmol/L) is where most men with symptoms live. The NHS won't treat here. Private TRT clinics will - if your free testosterone is also low and your symptoms are consistent.
Free Testosterone
Free testosterone is the fraction not bound to SHBG or albumin - the biologically active portion. Normal total testosterone with high SHBG can leave free testosterone very low. This is why total testosterone alone is insufficient.
Typical free testosterone reference range: 0.2-0.6 nmol/L (varies by lab). If you're below 0.3 nmol/L with symptoms, that's clinically meaningful regardless of your total T number.
SHBG
High SHBG binds more testosterone, reducing free T. Common causes of high SHBG: ageing, low insulin, hyperthyroidism, liver disease, excess alcohol. SHBG typically rises with age - men over 40 often have SHBG 10-20 nmol/L higher than they did at 25.
LH and FSH
These pituitary hormones tell you why your testosterone is low if it is:
- High LH + low testosterone: Primary hypogonadism - testes aren't responding to the signal. Usually requires TRT.
- Low LH + low testosterone: Secondary hypogonadism - the signal isn't being sent. Can sometimes be addressed with clomiphene or lifestyle changes.
- Normal LH + normal testosterone but symptoms: SHBG and free T are the likely explanation.
What to Do With Your Results
If your results are clearly low (under 12 nmol/L, symptomatic): book a consultation with a TRT-experienced clinician. The best TRT clinics in the UK offer initial consultations from under £100, including review of your bloodwork.
If your results are borderline (12-15 nmol/L): address the lifestyle foundations first - sleep, stress, body fat, training, micronutrients. Retest at 12 weeks. See our complete guide to boosting testosterone naturally.
If your results are normal and you're still symptomatic: look at thyroid, vitamin D, ferritin, and cortisol. The symptoms of hypothyroidism and testosterone deficiency overlap significantly. A comprehensive panel (Forth Advanced) covers both.
Test fasting, between 7-10am. Get at minimum: total T, free T, SHBG, LH. Don't accept "normal" as an answer without seeing your actual number and understanding the reference range. The BSSM treats symptoms below 12 nmol/L - the NHS threshold of 8 is outdated.
Seb tests quarterly with Forth Advanced Health Check, venous draw, Tuesday mornings, always fasting. All views are his own - see affiliate disclosure above.
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