Normal vs Optimal Blood Results for Founders

Reference ranges on a blood test are not health benchmarks. They are statistical averages built from the populations who walked into clinics, most of whom were already symptomatic.

For founders running €1M+ companies, "normal" is a population reference. "Optimal" is an operator reference. The gap between them is where decision quality, energy, and 10-year compound performance live.

Here is the part no one tells you when your GP says your numbers are fine.

Most reference ranges are calculated as the population average ± two standard deviations. That captures roughly 95% of the people who got tested. Anyone outside that 95% gets flagged. Everyone inside it gets told they are "normal."

The problem is the source population.

The people who walked into a clinic and had bloodwork done were not, on average, biologically optimized. They were a mix of people with vague symptoms, people doing routine annual screening at age 60+, and people whose insurance happened to cover it. The reference range is, in plain language, the statistical middle of a general clinical population.

That's how clinical reference ranges work, not a conspiracy. A standard panel is designed to flag disease, not to optimize cognition. The right tool for catching pneumonia, the wrong tool for protecting your decision quality at 55.

For a founder, this matters more than it does for almost anyone else. You are not paid to be average. You are paid to think clearly while running a company that has 15 hires depending on the next 6 months going well. You need above-average biology, and the standard panel cannot tell you whether you have it.

I want to draw a clean line here, because the wellness industry has muddied this badly.

This isn't biohacking. It's correcting for a known statistical bias in a clinical tool.

The reference range exists because in 1950 we needed a fast way to catch pathology. It works for that purpose. It does not define optimal biological function for high-cognitive-load work, and was never designed to.

Peter Attia has been making this argument for years: the "normal range" is descriptive, not prescriptive. It tells you where the population sits. It does not tell you where you should sit if your work depends on cognition holding up over 30 years. The "optimal" framing is contested in mainstream medicine.

Annastiina Hintsa, CEO of Hintsa Performance, made a related point in her 2021 McKinsey interview: wellbeing is the foundation of sustainable high performance, not a reward for it. You cannot build the foundation on numbers that were never designed to measure it.

The reframe: a founder optimizing their biology is doing the same thing a CFO does with the chart of accounts. Reading deeper than the standard report. Looking for the patterns that compound. That is asset management, not biohacking. The full operating model is in What should a founder actually track in blood work?.

These are the four markers I see GPs misread most often when working with founders. For each, I give the standard range, the functional range, and the biological consequence of the gap.

1. Ferritin. Your iron storage reserves

Standard range: 12–300 ng/mL (women), 20–300 ng/mL (men).

A ferritin of 15 ng/mL is "in range." It is also where you start to see brain fog, restless legs, reduced VO₂ max, and impaired exercise recovery, without anemia ever showing up on the hemoglobin reading.

A 2024 study in the Journal of Nutrition, Health and Aging found that in 2,176 people, higher ferritin went with better scores on thinking tests. The link held in people aged 65 and over, and only in men. The standard panel often shows normal hemoglobin while ferritin sits at the low end, masking the cause of fatigue and brain fog.

2. Free T3. Your active thyroid hormone

Standard range: roughly 2.3–4.2 pg/mL.
Functional optimum: the upper third of the range, roughly 3.2–4.2 pg/mL.

Free T3 is the metabolically active form of thyroid hormone. It crosses into your cells and drives cognitive function, energy production, and metabolic rate. Most GP panels skip free T3 entirely and rely on TSH alone.

A 2021 study in Frontiers in Aging Neuroscience found that even within the "normal" euthyroid range, lower free T3 levels were associated with worse cognitive function, particularly verbal fluency and executive function. The people in the study were not hypothyroid by clinical definition. Their TSH was fine. Their free T3 was suboptimal, and their cognition reflected it.

A founder with a TSH of 3.5 and a free T3 of 2.6 will be told everything is normal. They will also notice their afternoon focus is gone and assume they need more coffee.

3. Free testosterone. Drive and decision energy

Standard range: Most labs print 300 to 1,000 ng/dL for men. That is the lab's own range. The Endocrine Society measured healthy men aged 19 to 39 and got 264 to 916 ng/dL.
Functional optimum for cognitive performance: free testosterone in the upper half of the age-matched range, with total above roughly 500 ng/dL for men under 50.

Free testosterone is the unbound, biologically active fraction. Total testosterone can look fine while free testosterone is low because of elevated SHBG (sex hormone-binding globulin). Most standard panels measure total, not free.

A peer-reviewed study published in PMC analyzing NHANES data found that in men aged 60+, lower free testosterone concentrations were significantly associated with worse cognitive performance (including memory and executive function tests) even after adjusting for confounders. The pattern shows up earlier in chronically stressed populations.

For a founder, free testosterone influences drive, risk tolerance, and the energy needed to hold high-stakes decisions in working memory for 8–10 hours a day. Low-normal free testosterone is one of the most under-diagnosed contributors to founder fatigue.

4. Cortisol diurnal pattern. How your stress system runs

What a standard panel measures: a single morning cortisol level, sometimes nothing at all.
What actually matters: the full diurnal slope. Cortisol at waking, +30 min, midday, and evening.

A single cortisol reading tells you almost nothing. The clinically meaningful information is the shape of the curve across the day. Healthy biology produces a sharp morning peak within 30 minutes of waking (the Cortisol Awakening Response), followed by a steady decline to a low point at night.

A flattened diurnal slope (high morning cortisol that doesn't fall, or low morning cortisol that creeps up in the evening) is associated with disrupted HPA axis function. A meta-analysis published in Psychoneuroendocrinology via PubMed Central found that flatter diurnal cortisol slopes are associated with worse mental and physical health outcomes across multiple disease categories.

A salivary cortisol diurnal panel (four samples across one day) costs around €60–€90 and tells you something a single blood draw never will. The four-marker pattern is also covered in 4 Blood Markers GPs Miss in Founders.

You do not need a concierge medical practice to do this properly.

A comprehensive founder-tier panel can be ordered in most European countries through direct-to-consumer lab services for €200–€400 as of 2026. The panel I recommend my clients ask for includes:

• Full iron panel (ferritin, transferrin saturation, serum iron, TIBC)
• Full thyroid (TSH, free T4, free T3, reverse T3, anti-TPO antibodies)
• Hormones (total and free testosterone, SHBG, DHEA-S, oestradiol)
• Cortisol diurnal panel (salivary, four samples across one day)
• Inflammation markers (hs-CRP, homocysteine)
• Metabolic (HbA1c, fasting insulin, ApoB, lipid panel, omega-3 index)
• Vitamin D, B12 (active/holotranscobalamin), folate, magnesium

This is the exact panel I run on myself twice a year. Not a theoretical list. The one I book, pay for, and compare across time.

Total cost: €200–€400 as of 2026, depending on country and provider. Annual investment. Compare that to the cost of one bad strategic decision made through chronic biological fog.

I deliberately do not recommend a specific provider. The market changes too fast and the right provider depends on your country. Ask your network. Ask other founders. Most large European cities have at least two viable direct-to-consumer options.

They trust the "normal" without reading the number. A GP saying "your bloods are fine" is technically true and operationally useless. You need the number, the range, and where in the range you sit.

They run one panel and stop. A single blood panel is a snapshot. The trend over 2–3 panels in 12 months tells you whether you are improving, holding, or drifting. Most founders run one panel, do nothing with it, and forget.

They confuse expensive with optimal. A €2,000 concierge panel with 80 markers is mostly noise. The €300 panel with the right 20 markers is signal. Pay for precision, not for marker count.

They wait until something hurts. Bloodwork as a reactive tool is medicine. Bloodwork as a proactive tool is asset management. Most founders are still in the reactive paradigm and will not change until something breaks.

Find a direct-to-consumer lab in your country. Look at their panels. Pick one that includes, at minimum, ferritin, free T3 (not just TSH), free testosterone (not just total), and a cortisol diurnal slope.

Book it. €200–€400.

When the results come back, do not just look at the green checkmarks. Look at where each number sits inside the range. If ferritin is at the bottom 20th percentile of the range, that's information your GP would have called normal, and information that explains your afternoon energy crash.

Then write the numbers down. That is your biological balance sheet, Q1 entry. Three months from now, run the same panel. Compare.

• Peter Attia. VO₂ max, longevity, and the limits of standard testing
• Journal of Nutrition, Health and Aging. Ferritin and cognition, n=2,176, association in men aged 65 and over.
• Scientific Reports / Nature. Low free T3 and cognitive impairment in euthyroid adults
• PMC. Free testosterone and cognitive performance in older men (NHANES)
• PMC. Diurnal cortisol slopes and mental/physical health outcomes (meta-analysis)
• McKinsey. How wellbeing improves performance: interview with Annastiina Hintsa