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After 40 I want the numbers, not the symptoms. These twelve markers are the ones I check on myself twice a year, and they catch the issues that the standard NHS panel misses.
Most men in their 40s have never had a comprehensive blood test. They might get a cholesterol check at a routine GP appointment, or occasionally a full blood count if something feels off. But they've never seen the full picture of what's happening inside their body.
This is a significant gap. The conditions that will affect your health in your 50s and 60s - cardiovascular disease, type 2 diabetes, low testosterone, thyroid dysfunction - are already developing in your 40s. They're measurable. They're often reversible at this stage. But you can't act on what you can't see.
These are the 12 biomarkers every man over 40 should track at least once a year.
1. Free Testosterone
Not total testosterone - free testosterone. Total testosterone measures everything in circulation, including the large fraction bound to SHBG (sex hormone binding globulin) and albumin that your cells can't use. Free testosterone is the biologically active fraction.
Optimal range: 0.25–0.50 nmol/L (varies slightly by lab method)
Why it matters: Free testosterone declines by approximately 2–3% per year after age 30. By 40, many men have free testosterone levels that are technically "in range" but far below their personal peak. Symptoms - fatigue, reduced libido, poor recovery, reduced muscle mass, brain fog - often emerge well before numbers fall out of the reference range.
2. SHBG
SHBG determines how much of your testosterone is available to your cells. High SHBG means more testosterone is bound and inactive.
Optimal range: 20–40 nmol/L (higher end of reference range is associated with reduced bioavailable testosterone in most men)
Why it matters: SHBG rises with age, poor sleep, liver dysfunction, and certain dietary patterns (very low fat, very high fibre). Knowing your SHBG explains why two men with identical total testosterone can have completely different clinical pictures.
3. Vitamin D (25-OH-D)
Vitamin D is technically a hormone, not a vitamin. It's produced in the skin on exposure to UVB radiation and functions as a nuclear receptor ligand in cells throughout the body - including Leydig cells in the testes, where it directly supports testosterone synthesis.
Optimal range: 75–150 nmol/L (above 50 nmol/L is sufficient by NHS standards; 100 nmol/L is the functional optimum in most research)
Why it matters: A 2011 randomised controlled trial published in Hormone and Metabolic Research found that men supplementing with 3,332 IU of vitamin D daily for 12 months had 25% higher testosterone at the end of the study versus placebo. The majority of men in the UK have insufficient vitamin D by winter, and many are deficient.
4. hsCRP (High-Sensitivity C-Reactive Protein)
hsCRP is the most sensitive widely available marker of systemic inflammation. Inflammation directly suppresses Leydig cell testosterone production and is an early marker of cardiovascular risk.
Optimal range: Below 1.0 mg/L (1.0–3.0 is moderate risk; above 3.0 is high risk per AHA guidelines)
Why it matters: Most men with elevated hsCRP have no obvious symptoms. Yet chronic low-grade inflammation is associated with accelerated cardiovascular disease, reduced testosterone, insulin resistance, and all-cause mortality. It's a keystone marker.
5. HbA1c
HbA1c (glycated haemoglobin) measures your average blood glucose over the preceding 2–3 months. It's far more informative than a single fasting glucose reading.
Optimal range: Below 39 mmol/mol (below 5.7% in US units)
Why it matters: Insulin resistance and elevated blood glucose reduce testosterone through multiple mechanisms: they suppress SHBG (increasing aromatisation) and directly impair Leydig cell function. Pre-diabetes (HbA1c 39–47 mmol/mol) is present in a significant proportion of men over 40, often without symptoms. Catching it early means reversing it through diet and exercise before it progresses.
6. Thyroid Function (TSH + Free T3 + Free T4)
The thyroid regulates metabolism, energy, body temperature, and indirectly, testosterone. Both hypothyroidism (underactive thyroid) and hyperthyroidism (overactive) affect testosterone and SHBG levels.
Optimal ranges:
- TSH: 0.5–2.5 mIU/L (many men with "normal" TSH of 3–4 mIU/L have subclinical hypothyroid symptoms)
- Free T3: 4.0–7.0 pmol/L
- Free T4: 12–22 pmol/L
Why it matters: Thyroid dysfunction is more common than most people realise and is frequently subclinical - the standard NHS test (TSH only) misses cases where TSH is borderline but free T3 or T4 are suboptimal.
7. Full Lipid Panel (Including LDL Particle Size)
Total cholesterol, LDL, HDL, and triglycerides form a basic lipid panel. But the ratio matters more than any individual number.
Key targets:
- Total cholesterol: Below 5.0 mmol/L (though context matters - isolated high HDL can inflate this)
- LDL: Below 3.0 mmol/L
- HDL: Above 1.0 mmol/L (higher is better)
- Triglycerides: Below 1.7 mmol/L
- Triglyceride:HDL ratio: Below 1.5 (a powerful surrogate for insulin resistance)
Why it matters: Triglycerides and HDL together are among the best predictors of metabolic syndrome and cardiovascular risk. Elevated triglycerides with low HDL is a pattern strongly associated with insulin resistance. Testosterone and cholesterol also interact directly - testosterone is synthesised from cholesterol, and severely low LDL can be associated with reduced steroid hormone production.
8. Ferritin
Ferritin is the stored form of iron. It's one of the most frequently overlooked markers in men, who are often assumed to be iron-replete because they don't menstruate.
Optimal range: 100–200 ng/mL (reference range extends lower, but below 50 is associated with fatigue, reduced endurance, and impaired cognitive function even without anaemia)
Why it matters: Low ferritin without anaemia is a real and common condition in active men who don't eat red meat regularly. Symptoms include fatigue, poor exercise recovery, reduced motivation, and brain fog - symptoms that overlap completely with low testosterone. You can't tell which problem you have without measuring both.
High ferritin (above 300 ng/mL) is also a flag - it can indicate haemochromatosis (genetic iron overload) or elevated inflammation.
9. Vitamin B12
B12 is required for neurological function, red blood cell production, and DNA synthesis. Deficiency is associated with fatigue, peripheral neuropathy, cognitive decline, and mood disorders.
Optimal range: 300–500 pmol/L (reference range extends lower, but below 200 pmol/L is clearly deficient; 200–300 is a grey zone where symptoms frequently occur)
Why it matters: B12 deficiency is far more common than widely recognised in men over 40, particularly those who take proton pump inhibitors (PPIs) for acid reflux, metformin for blood sugar, or who eat limited animal products. Unlike most vitamins, B12 isn't readily available from plant sources.
10. PSA (Prostate-Specific Antigen)
PSA is a protein produced by prostate cells. Elevated PSA can indicate prostate enlargement (BPH), prostatitis, or prostate cancer - though it has significant false positive and negative rates and should always be interpreted with other clinical information.
Optimal range: Below 1.0 ng/mL for men under 50; below 1.5 ng/mL for men aged 50–59 (NHS guidance)
Why it matters: Prostate cancer is the most commonly diagnosed cancer in UK men. PSA testing is not a diagnosis, but baseline tracking from age 40 onwards - noting rate of change (PSA velocity) rather than absolute value - provides genuinely useful data.
11. Cortisol
Morning cortisol reflects adrenal function and HPA axis regulation. Chronically elevated cortisol suppresses GnRH production in the hypothalamus, reducing LH, reducing testosterone production, and promoting visceral fat deposition.
Optimal range: 140–500 nmol/L (morning, fasted draw)
Why it matters: Most men experiencing low testosterone alongside chronic stress, poor sleep, or high training volume will have elevated cortisol as a contributing cause. Addressing testosterone while ignoring cortisol means treating the symptom rather than the driver.
12. Full Blood Count
A full blood count (FBC) assesses red blood cells, white blood cells, haemoglobin, haematocrit, platelet count, and differentials. It's a broad-spectrum health check that catches anaemia, infection, immune issues, and (in the case of very high haematocrit) polycythaemia - which can be caused by testosterone replacement therapy.
Why it matters as a baseline: Beyond specific pathology, an FBC trend over years tells you whether your red cell production is declining (suggesting fatigue and reduced oxygen delivery), whether haemoglobin is falling (nutritional deficiency, chronic disease), and whether your immune markers are shifting.
How to Get All 12 Tested
A standard NHS GP appointment will test a fraction of these. Waiting times for hormone panels are long, and GPs typically only investigate when symptoms are already significant.
Lola Health's Male Health Blood Test covers all 12 of these markers (and more - 40+ biomarkers in total) with a simple at-home finger-prick collection. Results arrive within 48 hours via the app, with plain-English explanations of each marker.
Testing once in January and once in July gives you a seasonal comparison that accounts for the natural variation in vitamin D and testosterone across the year.
The investment is trivial compared to the cost of managing the conditions these markers detect at an early stage.
Tracking these twelve markers annually catches the conditions that quietly develop through your forties. Pair the numbers with symptoms and trend them, the direction matters more than the single result.
This article is for educational purposes. Reference ranges vary by laboratory and individual context. Discuss any concerning results with your GP or a men's health specialist.
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