Bloodwork & Diagnosis
Your total testosterone came back at 14 nmol/L. The reference range on the report goes from 8 to 30. Your GP smiled, said "all normal," and suggested you might want to look at your sleep or your stress levels.
You walked out feeling exactly the same as when you walked in: tired in the afternoons, libido at a fraction of what it was at 30, motivation lower than it should be, the gym a chore rather than a relief. Something is wrong. But the numbers say otherwise, so either you are wrong, or the numbers are missing something.
The numbers are missing something. This article explains what — and how to ask for the right tests next time so you do not waste another six months wondering.
There are three common scenarios where a man can have a "normal" total testosterone and a genuine androgen problem at the same time. The medical literature is clear on all three. The clinical practice has not caught up.
This is the most common version. Roughly one in three men with low-T symptoms and a "normal" total testosterone reading turn out to have elevated SHBG — sex hormone binding globulin — that is locking up most of their circulating testosterone.
Here is what that looks like in practice. Imagine two men, both with a total testosterone of 18 nmol/L. Man A: SHBG 25 nmol/L (mid-range). Free testosterone calculated at 0.42 nmol/L. Feels normal. Man B: SHBG 65 nmol/L (high). Free testosterone calculated at 0.22 nmol/L. Feels terrible. Same total. Half the bioavailable testosterone. Identical lab printout if you only look at the "T" line.
SHBG rises with age, with low calorie intake or aggressive dieting, with high alcohol consumption, with hyperthyroidism, and with certain medications (some anticonvulsants, opioids). High-fibre, low-fat diets also push it up.
The first step is asking your doctor for SHBG to be added to the next panel. Or, faster, ordering a private panel that includes it as standard — services like Medichecks and Forth in the UK, or Everlywell in the US, include SHBG in their basic hormone panels.
Once you have your SHBG number, you can calculate free testosterone yourself using the Vermeulen formula. The free T calculator on our assessment page runs the math automatically — you put in total T, SHBG, and albumin (default 4.3 g/dL is fine if you do not have the reading), and it returns your free T.
If your free T is below 0.30 nmol/L and your symptoms are real, you have a diagnosable problem. The total T being "normal" is incidental.
The UK lab cut-off for "low" total testosterone is usually 8 nmol/L. Below that, a GP will start considering hypogonadism. Above 8 nmol/L, the standard view is "your testosterone is fine."
The problem is that the symptom profile of clinical low T — fatigue, low libido, mood changes, lost morning erections, reduced muscle mass, increased belly fat — often appears at total testosterone levels well above 8 nmol/L. The European Male Ageing Study, published in 2010, established that symptoms become more common below roughly 11 nmol/L for sexual symptoms and around 13 nmol/L for psychological symptoms.
A man with a total T of 10 nmol/L, no other obvious cause for his symptoms, and a measurable improvement in those symptoms when his T is raised, is not a man whose testosterone is irrelevant to how he feels — even if his lab report says "normal."
This is where the optimal-range framework matters more than the lab range. The lab range is statistical; the optimal range for symptom-free men in their 30s and 40s is 18–30 nmol/L for total T. A man at 10 is in the lab range. He is also miles below where his body wants to be.
This is the least common case, and the hardest to diagnose, but it does exist. Androgen receptor sensitivity varies between men. The same level of free testosterone produces a stronger biological response in some men than in others.
There is no routine blood test for this. The way it shows up in practice is a man whose blood markers all look fine, whose lifestyle is reasonable, who has ruled out the obvious mimics — and who still has clear, persistent androgen-deficiency symptoms. In a research setting, this is sometimes confirmed with a CAG repeat length analysis (a genetic test of the androgen receptor). In clinical practice, it is usually a diagnosis of exclusion.
If you have worked through the first two scenarios and still have unresolved symptoms, this is worth raising with an endocrinologist. It does not mean your case is hopeless — it means the threshold at which interventions help may be different for you.
Before assuming a "normal panel + bad symptoms" picture is hidden low testosterone, work through the conditions that produce identical symptoms. Several of these are more common than low T itself, especially in men over 40.
The symptom overlap with low testosterone is almost total. Fatigue, weight gain, low mood, low libido, cold intolerance, brain fog, slower recovery from exercise. Subclinical hypothyroidism — where TSH is elevated but T4 is still in range — affects roughly 4–8% of men, rising with age.
Standard NHS panels often check only TSH. A TSH of 3.5 will be reported as normal (the lab range typically goes up to 4.5 or higher). It is also the level at which a significant fraction of men begin showing thyroid-related symptoms.
If your testosterone panel is clean and you have symptoms, ask for a full thyroid panel: TSH, Free T4, and Free T3. The third one is the metabolically active form, and it can be low while TSH still looks normal. Private testing services like Thriva include the full thyroid panel as standard.
Iron deficiency without obvious anaemia is common, particularly in men with high training volumes, gut issues, or regular blood donors. It produces fatigue, low motivation, reduced exercise capacity, and shortness of breath on exertion — all easily mistaken for low T.
Ferritin (the storage form of iron) below 30 ng/mL is functionally deficient even if haemoglobin is normal. Above 300, the picture flips — iron overload (haemochromatosis) suppresses testosterone in its own right. Both ends matter.
In the UK and Northern Europe, vitamin D status below 50 nmol/L is the norm rather than the exception through autumn and winter. Symptoms include fatigue, low mood, frequent infections, joint aches, and reduced exercise tolerance.
Vitamin D is also required for testosterone synthesis. Correcting a deficiency raises testosterone modestly in deficient men — not dramatically, but reliably. A daily vitamin D3 with K2 supplement at 2,000–5,000 IU is the simplest correction available, and one of the few supplement interventions with consistent evidence behind it.
This one is often missed in men presenting with low-T symptoms. Untreated obstructive sleep apnoea (OSA) suppresses testosterone directly through fragmented sleep architecture, and treating it raises T. The classic signs are loud snoring, witnessed pauses in breathing, morning headaches, and feeling unrefreshed despite sleeping enough hours.
If your partner has commented on your snoring or breathing pauses, push for a sleep study before chasing hormonal interventions. Sleep apnoea explains a meaningful fraction of "treatment-resistant" low T.
This one is uncomfortable but important. Clinical depression produces a symptom profile that overlaps heavily with low testosterone — fatigue, loss of interest, low motivation, low libido, sleep disturbance, weight changes. The two conditions can also coexist; low T can worsen depressive symptoms, and depression can suppress testosterone.
If your panel is genuinely normal across the board, the lifestyle picture is solid, and the symptoms persist, depression deserves a serious consideration. Your GP is the right starting point. This is not a failure of the protocol — it is the protocol doing its job by ruling things out.
If you go in armed with the right requests, the conversation tends to go differently. A standard low-T workup in the UK is "total testosterone, repeat if low." That is the floor. Here is the ceiling — what you can reasonably ask for, and why:
1. Total testosterone, SHBG, free testosterone, oestradiol. The core hormone panel. SHBG is the missing piece in most NHS workups.
2. LH and FSH. Tells you whether the problem is testicular or pituitary. Changes the treatment path.
3. Prolactin. Rules out a pituitary tumour as a cause of low T.
4. Full thyroid panel (TSH, Free T4, Free T3). Rules out the most common mimic.
5. Vitamin D, ferritin, HbA1c. Three cheap, high-yield supporting markers.
6. Lipid panel and liver function (ALT, AST, GGT). Background metabolic health.
Some GPs will order all of this. Many will not, citing cost or local protocols. If you hit resistance and the symptoms are real, paying for a private panel is the faster path. A comprehensive hormone panel from Medichecks or Everlywell costs less than two months of badly-spent supplement money, and the data is yours to take to any clinician.
The companion piece to this article — How to Read Your Blood Test Results — walks through each marker in detail with optimal ranges, so you can interpret what comes back without waiting for an appointment.
Some of the time, after a comprehensive panel, the answer is honestly that the bloodwork does not explain the symptoms. That happens. It does not mean you are imagining things. It means the cause is in something the blood does not measure.
The most common candidates, in rough order: sleep quality, not just sleep quantity. You can sleep eight hours and still be cognitively impaired if your sleep architecture is wrecked. See our companion article on sleep duration vs quality. Chronic low-grade stress. Persistent cortisol elevation produces a symptom picture identical to low T even when T is fine. Inadequate calories or protein. The chronic dieter or the busy professional who skips meals often has hormones that are technically fine and an energy economy that is broken.
Sedentary lifestyle masked by busy work — sitting for eleven hours a day, even with thirty minutes at the gym, produces fatigue that no hormone level can override. And excessive endurance training: volume above roughly 100 km per week of running, or equivalent, raises cortisol and produces symptoms that mimic low T. See why cardio can be tanking your testosterone.
If the panel is clean and you have ruled out the mimics, the answer is rarely "more hormones." It is usually "fix the input the body needs to make and use them properly."
Chapter 13 of The Testosterone Blueprint covers every marker, every mimic, and every scenario in detail. Plus Card B5 — the printable list of questions to take to your next appointment so you do not leave without the answers.
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