When Blood Test Norms Don’t Reflect True Health

When the “Norm” Drops: What Blood Test Ranges Don’t Always Reveal

by Laurent Glatz – for Athletic Carnivore

We often look at a blood test like a verdict.
A value. An arrow. A range. Too low. Too high. Normal.

Then the doctor says: “Everything is fine, you’re within the norms.”

But a troubling question deserves to be asked: within whose norms?
Within the norms of a robust, active man, well-nourished, who sleeps deeply, digests properly, has functional muscle mass and low inflammation?
Or within the norms of a modern population increasingly fatigued, insulin resistant, stressed, sedentary, under-medicated, nutrient deficient, overfed in energy but undernourished in nutrients?

This is where the subject becomes explosive.

Because a biological range is not necessarily a definition of health. Very often, it’s a statistical snapshot of a given population. And if that population deteriorates, “normality” can slip along with it.

A range is not a biological truth

In the lab, a reference value is generally built from a group of people considered as the “reference.” Then a statistical distribution, often the central 95%, is used to determine what will be displayed as “normal” on your report. In other words, a range often describes what is common in a group, not necessarily what is optimal for a fully healthy human being.

That’s a huge nuance.

Because if you measure a population where many people sleep poorly, eat too many refined carbs, lack quality animal protein, live under chronic stress, gain weight, lose muscle, and gradually develop insulin resistance, then the “average” of that population will shift.

And if the average shifts, the range is likely to shift.

The problem is therefore not the blood test.
The problem is the lazy interpretation of the blood test.

Biology never simply says: “you are within the norm.”
It asks: in what context?

The case of testosterone: when low becomes acceptable

Let’s take the most telling example: testosterone.

Today, we often find very wide ranges. Some modern references place adult male total testosterone around a few hundred ng/dL up to about 900 or 1000 ng/dL depending on labs, assay methods, age, and populations used. A harmonization study published in 2017 proposed, for non-obese men aged 19 to 39, a range of 264 to 916 ng/dL, with a median around 531 ng/dL.

On paper, this seems scientific.
But you have to look at what it means.

If a young man, tired, with low libido, poor recovery, decreased motivation, fragile sleep, abdominal fat gain, and loss of strength tests at 310 ng/dL, he can be “within the norm.” Statistically, yes. Biologically, the question remains open.

Is this his ideal level?
Is this his historical level?
Is this the level at which his brain, muscles, mood, fertility, and nervous system function best?
Or is it simply a level that has become common in a metabolically declining modern population?

This is where “normal” can become dangerous: it can anesthetize reflection.

Do we really have testosterone data from 100 years ago?

We must be honest: precisely comparing today’s testosterone levels with those from a century ago is very difficult. Assay methods were different, large databases didn’t exist, and modern lab standards don’t allow clean overlap across eras.

So it would be dishonest to claim: “100 years ago, men were all at such a level.”

However, more recent data indicate a population decline. A study published in 2007 observed a significant drop in testosterone levels among American men over several measurement waves between the late 1980s and early 2000s, a decline not explained solely by age.

This point is fundamental.

Because if two men of the same age, at two different times, don’t have the same average hormone levels, then we’re no longer just talking about aging. We’re talking about environment.

And the modern environment has changed much faster than our genetics.

Man hasn’t changed, but his terrain has

This is probably the central sentence of the article:

Biological man hasn’t had time to evolve in 50 years. But his environment has mutated abruptly.

Artificial light late at night.
Shortened sleep.
Chronic stress.
Sedentarism.
Less sun exposure.
Less muscle mass.
More visceral fat.
More processed food.
More industrial oils.
More sugars.
More snacking.
Less truly satiating protein.
Less organ meat, collagen, natural animal fats.
More endocrine disruptors.
More medications.
More contradictory signals sent to the nervous system.

The human body is not an isolated machine.
Testosterone is not produced in a vacuum.
The thyroid doesn’t work in a vacuum.
Insulin doesn’t rise by chance.
Cholesterol doesn’t circulate without reason.
Blood sugar doesn’t deregulate on its own.

Every blood marker is a consequence. Not just a number.

The trap: confusing “common” with “normal”

Within the Athletic Carnivore framework, one point often comes up: many so-called normal values may be too broad to judge an optimal state.

Fasting blood sugar, for example, is often considered “normal” up to about 100 mg/dL. But some metabolism-focused clinicians consider a truly optimal zone much narrower, around the mid-80s mg/dL, depending on diet context, adaptation to low carb or carnivore, fasting, physical activity, and insulin sensitivity.

Same logic applies to potassium: a range might indicate 3.5 to 5, but someone at 3.6 can be technically “normal” yet show functional signs: fatigue, unstable blood pressure, cramps, water retention, neuromuscular irritability. Biology is not just a number. It’s a number + terrain + symptoms.

And that’s where the perspective shifts.

A blood test should not only answer the question:
“Am I sick according to the lab?”

It should also open another question:
“Is my body functioning at its best possible level?”

This is not the same medicine.
This is not the same ambition.
This is not the same man at the end of the road.

Markers that have shifted

Testosterone is not the only example.

We can reflect on several markers whose modern interpretation has become problematic.

1. Testosterone

The low end of the range can include men who, in the past, might have been considered clearly insufficient functionally. The problem is not only sexual. Testosterone affects motivation, strength, recovery, bone density, body composition, mood, and capacity to face effort.

A man “within the norm” can be biologically extinguished.

2. Blood sugar

A “normal” blood sugar can mask insulin that is already too high. The body can maintain glucose within range for years by secreting more insulin. The number seems reassuring, but the metabolic cost silently rises.

This is one of the great modern traps: waiting for blood sugar to rise before recognizing the problem, while insulin has already been compensating for a long time.

3. Triglycerides and HDL

From a low carb / carnivore perspective, the triglycerides-HDL pair often tells more than total cholesterol alone. Low triglycerides with decent HDL can signal better energy management, while isolated total cholesterol can scare without context.

The body transports energy. It doesn’t just accumulate “good” and “bad” numbers.

4. LDL cholesterol

This is probably one of the most misunderstood markers. In the classic model, LDL is often viewed as an isolated threat. But in a very low-carb diet, with low triglycerides, high HDL, low inflammation, and good insulin sensitivity, high LDL doesn’t necessarily mean the same as in an insulin-resistant, inflamed, sedentary, hyperglycemic person.

The same number can tell two different stories.

5. TSH and thyroid

A “normal” TSH is not always enough to understand thyroid function. The body can deliberately slow certain energy expenditures depending on stress, fasting, calorie restriction, carb intake, inflammation, or recovery level. T3, T4, symptoms, body temperature, energy, digestion, and nervous system also matter.

The lab gives a snapshot. Not the whole movie.

6. Vitamin D

Here too, being “within the norm” is not necessarily being in an optimal zone. The level reflects sun exposure, lifestyle, inflammation, absorption, liver status, gut health, and sometimes season. A value cannot be isolated from the person who carries it.

Why do norms shift?

Norms shift for several reasons.

First, because populations change. If the reference population becomes heavier, older, more insulin resistant, or more medicated, biological distributions change.

Second, because assay methods evolve. Two labs, two machines, two analytical techniques can give different values. That’s why harmonization efforts have been made, notably for testosterone.

Finally, because modern medicine often works with intervention thresholds. It doesn’t always seek the optimal. Sometimes it seeks the level at which a diagnosis is made, a treatment reimbursed, an alert triggered, or a patient classified.

But real health doesn’t start when the system finally accepts that you are sick.

It starts much earlier.

The real problem: we medicalized the threshold, not the decline

This may be the most important point.

When a marker slowly declines over 10 or 20 years, we often wait for it to cross the red line to act. As long as it stays within the range, we reassure.

But the body doesn’t operate administratively.

A man can drop from 850 to 520 ng/dL testosterone and be “normal” both times. Yet for him, the difference can be immense. Less drive. Less recovery. Less desire. Less muscle. Less momentum. Less stress tolerance.

A woman can have “acceptable” ferritin but feel drained.
An athlete can have a correct TSH but poor thyroid conversion.
A man can have normal blood sugar but already too high insulin.
A patient can have LDL considered worrying while his overall metabolic profile tells a much more nuanced story.

The range doesn’t always see the trajectory.
It sees the moment.

Yet health is often the trajectory.

The troubling question: are we adapting norms to disease?

This is where the reader must reflect.

If a population becomes progressively sicker, should we continue to use that population to define normality?

If modern men have less testosterone than before, should we lower our expectations?
If people have higher blood sugar, should we widen our tolerance?
If fatigue becomes common, should we call it “aging”?
If libido collapses at 40, should we call it “normal”?
If digestion, mood, sleep, and energy degrade, should we wait for a coded pathology?

It’s a question of medical philosophy as much as biology.

Do we want to define health by absence of diagnosis?
Or by capacity to function fully?

What an intelligent blood test should be

A useful blood test should never be read alone.

It should be confronted with:

- actual diet;
- amount of animal protein;
- fat intake;
- carb tolerance;
- probable insulin level;
- muscle mass;
- sleep;
- stress;
- libido;
- sports recovery;
- body temperature;
- energy upon waking;
- digestion;
- inflammation;
- medical history;
- symptoms;
- evolution over time.

A number without context can falsely reassure.
A number with context can become a valuable clue.

This is exactly why a serious carnivore or low carb approach should never be reduced to “just eating meat” or “cutting carbs.” The subject is more subtle. You have to look at how the body responds: energy, sleep, mood, digestion, strength, blood sugar, triglycerides, HDL, blood pressure, electrolytes, hormones, recovery.

Nutrition is not a religion.
It’s an intervention on the biological terrain.

The conclusion no one wants to hear

Lab ranges are useful.
But they are not sacred.

They can help detect an obvious problem.
But they can also let a silent decline slip by.

They can say: “you are not out of range.”
But they can’t always say: “you are at your optimal level.”

And that’s where everyone must take responsibility for their body.

The real question is not only:
“Are my testosterone, blood sugar, cholesterol, TSH, or vitamin D within the norm?”

The real question is:

“Do these values correspond to a body that functions, recovers, thinks, sleeps, digests, desires, builds muscle, and produces energy as it should?”

Because a man can be “normal” on paper and diminished in life.
A woman can be “normal” on paper and exhausted in her body.
An athlete can be “normal” on paper and underperforming for years.

And maybe the real scandal is not that norms have changed.

Maybe the real scandal is that we have accepted confusing the modern average with human health.