Free vs Metabolized Cortisol on a DUTCH Test
A patient with low cortisol and a patient who is clearing cortisol quickly look identical on a saliva test and need opposite things. Measuring only the free fraction is why so many exhausted patients get the same protocol and only some of them improve.
One number isn't enough
Cortisol is not a quantity sitting still in the blood. It is produced, bound, freed, used, converted and cleared, and a single measurement catches one moment of one of those processes.
Saliva testing — which is what most practitioners have used for years — measures the free fraction. That is the bioavailable cortisol, the part that can act on a receptor. It is genuinely useful and it is one variable.
So picture two patients. Both exhausted, both wired at night, both with low free cortisol across the day. One is producing very little cortisol. The other is producing a perfectly normal amount and clearing it so fast that very little is free at any moment.
Same numbers. Different problem. And if you support adrenal output in the second patient you are pushing on a gland that was never the issue.
The DUTCH's actual contribution is not that it uses urine. It is that it reports the metabolites alongside the free fraction, which lets you tell those two patients apart.
Two different measurements
Free cortisol is the unbound, bioavailable fraction — what is available to act, sampled at the points across the day the collection asks for. It is what saliva measures and it reflects exposure.
Metabolized cortisol is the sum of the downstream metabolites, principally tetrahydrocortisol and tetrahydrocortisone. Because nearly everything produced eventually appears as metabolites, this is the closer estimate of total daily production.
The distinction is simple to state and it is where the clinical reasoning lives:
Free cortisol tells you how much is available. Metabolized cortisol tells you how much was made.
The gap between them is clearance — how quickly the body is processing and disposing of what it produces. Clearance is not a footnote. It is strongly influenced by thyroid status, liver function, body composition and chronic stress, which means the cortisol picture is frequently a thyroid or liver picture wearing a different label.
The four patterns
Two measurements, each high or low, gives you four pictures — and this is the table worth committing to memory.
Metabolized low | Metabolized high | |
Free low | Genuinely low output. The low metabolites confirm the low production | Production is fine, clearance is fast. Seen with hyperthyroidism and chronic stress |
Free high | Sluggish clearance. Common with hypothyroidism, anorexia, poor liver function | Genuinely high output. Treat the driver |
The two diagonals are the ones a free-only test cannot distinguish, and they are the ones that matter.
Free low, metabolized high is the exhausted patient whose adrenals are working perfectly well. Supporting output here does little, because output was never the problem. Clearance is — and the next question is why. Thyroid is the first place to look.
Free high, metabolized low is the opposite: a patient with high exposure and modest production, holding onto cortisol because clearance is slow. Again the useful question points away from the adrenals — hypothyroidism, poor liver function, restricted intake.
In both cases the DUTCH is pointing you at a different organ than the one you were planning to treat. That is the whole value of measuring both.
Cortisol, cortisone and clearance
The report gives you cortisone as well, and it is not decoration.
Cortisone is the inactive form, made directly from cortisol. The conversion between them is an enzymatic switch the body uses to decide how much active hormone a tissue is actually exposed to — so the relationship between the two is a readout of regulation rather than of production.
The metabolites carry the same kind of information. The preference between tetrahydrocortisone and tetrahydrocortisol lets you estimate the clearance rate, which is the variable that explains most of the confusing reports you will see.
What this adds up to practically: a cortisol result is three questions, not one.
How much is being produced?
How much is available?
How fast is it being cleared and converted?
A single free cortisol answers the second. Most of the treatment decisions depend on the first and third.
The CAR stands apart
The cortisol awakening response — the rise in the thirty to forty-five minutes after waking — is not simply the first point on the daily curve. It is regulated differently from the rest of the day and carries its own information, which is why it gets its own collection and its own interpretation.
What it bears on:
Energy on waking
Stress resilience, and how much stress a person perceives
Alertness
Blood sugar regulation
That second one is worth sitting with. The CAR tracks not just how much stress someone is under but how much they feel under — which is often the gap between two patients with identical lives and completely different experiences of them.
Clinically, a blunted CAR in a patient with an otherwise reasonable curve is a finding in its own right. It is also the measurement most often ruined by collection error: if the patient sleeps in, checks their phone first, or mistimes the waking sample, you are reading noise. Confirm how they actually collected it before you interpret it.
So what about adrenal fatigue
The term does not hold up, and the patients are real. Both things are true and it is worth being clear about which part you are keeping.
The model said chronic stress wears the adrenals out until they cannot produce enough. The gland does not work that way, the staged progression was never demonstrated, and the phrase has been reviewed and rejected often enough that using it in front of a physician colleague costs you credibility you will want later.
What is well supported is that the HPA axis dysregulates — signalling between hypothalamus, pituitary and adrenal changes under sustained load, the diurnal rhythm flattens or inverts, and the CAR blunts. That is a regulation problem, not an exhaustion problem, and it explains the patient in front of you at least as well.
The practical difference is not semantic. Exhaustion implies the answer is to push output up. Dysregulation asks what the axis is responding to — load, sleep, blood sugar, inflammation, thyroid, a long-running stressor nobody has addressed — and whether clearance is distorting the picture.
Drop the phrase. Keep the patients. The testing got better and the framing should follow it.
Where to start
Read metabolized before free. Establish production first. Reading the free curve on its own is how you end up treating the wrong variable.
Place the patient in the 2x2. The quadrant, not the number, decides where you go next.
If clearance is the story, leave the adrenals alone. Check thyroid, liver and intake. The cortisol result was pointing somewhere else.
Read the CAR separately, and confirm the collection was done properly before you believe it.
Ask what the axis is responding to. Sleep, blood sugar, inflammation, an unresolved stressor. Supporting the axis without changing the load buys months, not resolution.
The GHT Academy Hormone Guide carries DUTCH interpretation end to end — cortisol free and metabolized with the patterns laid out, the CAR, estrogen, progesterone and androgens, Phase I, II and III hormone detoxification, and condition-specific protocols with supplement dosing for each imbalance. It is the reference I built for my own team.
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