Testing for Mold Illness: What to Order and How to Read It

The markers that first suggest mold exposure are usually already sitting in labs you ordered for something else. They look non-specific one at a time, which is exactly why the pattern gets missed for years.

Why it gets suspected late

Mold-exposed patients do not arrive saying they have been in a water-damaged building. They arrive with fatigue, brain fog, air hunger, unexplained weight gain, light sensitivity, static shocks, headaches and anxiety — a list long enough that it reads as somatic rather than as a pattern.

Then the first round of labs comes back unremarkable, or non-specifically inflamed, and the working diagnosis becomes stress, or perimenopause, or dysautonomia, or nothing. Years pass. By the time anyone asks about the basement, the patient has been through four practitioners.

The tell is not any single marker. It is a multi-system complaint list in a patient whose ordinary bloods look vaguely inflamed and specifically normal. That combination deserves one question before you order anything: has this person ever lived or worked somewhere with water damage? It costs nothing and it reframes everything downstream.

Tier 1: the pattern in labs you already have

None of these markers means mold on its own. Read as a cluster in the right history, they are enough to justify looking further.

Marker	What you may see
CBC	High neutrophils, high eosinophils — or low WBC with relatively low lymphocytes
CMP	High AST, ALT, GGT, bilirubin
CRP	Elevated: systemic inflammation with no obvious source
ANA	Positive, without a clean autoimmune picture behind it
Cytokines	High IL-6, IL-10, TNF
Immunoglobulins	IgE positive for mold; IgG, IgM or IgA for candida
Food allergy panel	Positive to peanuts, yeast, coffee, mushrooms, corn, grains
SIBO breath test	Positive, or a patient who keeps failing to clear it
Nutrients	Low iron, low RBC, low glutathione, low vitamin D

Two of these are worth dwelling on.

The fungal-adjacent food reactions. Peanuts, yeast, coffee, mushrooms, corn and grains are the foods most likely to carry mould or share cross-reactive antigens. A patient reacting across that specific cluster is telling you something that a general "lots of food sensitivities" reading throws away.

The SIBO that will not clear. If you have a patient who responds to treatment and relapses, repeatedly, mould exposure is one of the reasons the terrain keeps re-forming. Treating the overgrowth again is not the answer.

Tier 2: the CIRS panel

These are the markers almost nobody orders, and they are where the picture either firms up or falls apart.

Marker	Expected	What it tells you
MSH	> 35 pg/mL	Melanocyte stimulating hormone, regulating the pituitary. Low MSH means increased susceptibility to mould toxins, and it governs inflammatory pathways and defence in the gut and respiratory tract
TGF beta-1	< 2380 pg/mL	Regulatory effects on innate immunity; rises with toxic burden. Measure alongside C4a
C4a	0–2830 ng/mL	Complement activation. Can rise within 4–12 hours of exposure to a water-damaged building — and may be suppressed in patients with MARCoNS
MMP-9	85–332 ng/mL	Excess disrupts tissue in blood vessel walls; inflammation of brain, lungs, muscles, nerves and joints
VEGF	31–86 pg/mL	Low VEGF is common and serious in CIRS — cells starve without adequate blood flow
VIP	23–63 pg/mL	Often low in CIRS and multiple chemical sensitivity. Watery diarrhea or breathlessness on exertion
HLA-DR	—	Genetic susceptibility. Explains why one person in a household is unwell and the others are not

The C4a line is the one worth remembering. It moves fast — within hours of re-exposure — which makes timing relative to where the patient has been genuinely informative. And it can be suppressed by MARCoNS, so a normal C4a in a patient who otherwise fits does not close the question.

The HLA-DR line answers the objection you will hear constantly: my husband lives in the same house and he's fine. Susceptibility is partly genetic. One person reacting is not evidence that the building is innocent.

The building and the patient are two questions

Testing one does not answer the other, and conflating them wastes money in both directions.

Testing the building establishes whether there is a source. This matters more than people expect, because if the patient goes home to it every night, nothing you do clinically will hold. A patient who improves on holiday and relapses within a week of returning has told you where the problem is without any test at all.

Testing the patient establishes whether their physiology is responding. A urinary mycotoxin panel reports what is being excreted; the CIRS markers report what the immune system is doing about it.

Two practical notes on mycotoxin testing. First, provoked versus unprovoked is a real decision with real disagreement behind it — provocation can raise excretion and make a finding visible, and it can also muddy what the result means. Decide which you are doing and why, before you order. Second, a negative urine panel does not clear the patient. Excretion depends on the detoxification pathways that are often the thing impaired.

The mistake to avoid is testing the patient exhaustively while never asking where they sleep.

What is contested, and what isn't

This field attracts more certainty than the evidence supports, in both directions. Know which ground you are standing on.

Not contested. Water-damaged buildings grow mould. Mould produces mycotoxins. Mycotoxins are biologically active. Some people living in damp buildings get sick and get better when they leave. None of that is fringe.

Contested. CIRS as a defined diagnostic entity, the specific biomarker panel used to establish it, and the cutoffs applied to those markers are not accepted across mainstream medicine. The markers themselves are real and measurable; what is argued is how specific they are and what weight any one of them should carry.

Reasonable position. Use the panel as a structured way to decide whether this hypothesis is worth pursuing, not as a diagnosis you hand a patient. Document your reasoning. Stay inside your scope. If you tell a patient they have a condition large parts of medicine do not recognise, you have made their next ten appointments harder, not easier.

The practitioners who do well with these patients are the ones who can hold both — taking the exposure seriously while being straight about what the testing can and cannot establish.

Where to start

1. Ask the history properly. Every building the patient has lived or worked in. Flooding, roof leaks, a damp basement, a bathroom that never dried out. Do they improve away from home?

2. Re-read the labs you already have for the Tier 1 cluster. You may not need a single new test to decide whether this is worth pursuing.

3. Establish the source before you treat. Remediation or relocation is not an afterthought — it is the intervention. Everything else is symptom management while the exposure continues.

4. Then run Tier 2, if the picture holds and the patient can afford it. MSH, TGF beta-1, C4a and VEGF will tell you more than another round of ordinary bloods.

5. Expect it to be slow. These patients have usually been unwell for years and are often sensitive to everything, including your treatment. Starting gently is not caution, it is how you avoid losing them in week two.

The GHT Academy Detox Guide covers the testing in full — Tier 1 and Tier 2 with every marker and its range, exposure sources for mould and heavy metals, treatment options with specific product dosing, and managing Herxheimer reactions when a sensitive patient reacts to the thing meant to help. It is the reference I built for my own team.