Patients being evaluated for Chronic Inflammatory Response Syndrome (CIRS) frequently encounter a collection of blood tests sometimes referred to as “biotoxin labs.” The name is somewhat misleading because most of these tests don’t actually measure mold toxins or other biotoxins in the bloodstream. Instead, they look for changes in the body’s immune, inflammatory, vascular, and hormonal systems that may occur following certain environmental exposures.
These laboratory markers are most closely associated with the work of Dr. Ritchie Shoemaker and the Shoemaker CIRS protocol. The basic hypothesis is that some genetically susceptible people exposed to a water-damaged building develop an abnormal inflammatory response that does not shut down normally.
Although mold gets most of the attention, a water-damaged building contains much more than mold. The environment can include fungal fragments, bacteria, Actinobacteria, endotoxins, beta-glucans, and numerous other microbial products.
The purpose of the laboratory evaluation is therefore not simply to ask, “Have you been exposed to mold?” A better question is:
Is there evidence that your immune system and other regulatory systems are behaving abnormally following an environmental exposure?
C4a: Looking at the Innate Immune System
The complement system is one of our most primitive and rapid immune-defense mechanisms. When activated, complement proteins break apart into smaller fragments that help coordinate inflammation.
C4a is one of these fragments.
Within the CIRS model, an elevated C4a may suggest excessive activation of the innate immune system—the rapid, nonspecific portion of immunity that responds before antibodies become involved.
However, C4a is not a mold test. Complement activation can also occur with infections, autoimmune diseases, immune complexes, and other inflammatory conditions.
An elevated C4a therefore tells us more about immune activation than it does about the cause of that activation.
TGF-β1: Inflammation, Immune Regulation, and Fibrosis
Transforming growth factor beta-1 (TGF-β1) is an important signaling molecule involved in immune regulation, tissue repair, and fibrosis.
TGF-β1 communicates with immune cells, influences T-cell behavior, activates fibroblasts, and regulates the production of collagen and other components of the extracellular matrix.
Within the Shoemaker model, elevated TGF-β1 is interpreted as evidence of abnormal inflammatory and immune signaling.
TGF-β1 is particularly interesting because excessive activity can promote:
inflammation → fibroblast activation → collagen production → tissue remodeling and fibrosis
However, elevated TGF-β1 is not specific for CIRS. Abnormal TGF-β signaling occurs in many inflammatory, autoimmune, fibrotic, cardiovascular, and other medical conditions.
MMP-9: Inflammation and Tissue Remodeling
Matrix metalloproteinase-9 (MMP-9) is an enzyme involved in remodeling the material surrounding our cells.
MMP-9 also participates in inflammatory signaling and influences how inflammatory molecules move between the bloodstream and tissues.
Within the CIRS model, elevated MMP-9 is proposed to contribute to symptoms such as muscle discomfort, headaches, fatigue, and cognitive difficulties.
Like the other markers, however, MMP-9 is nonspecific. It can be elevated with obesity, cardiovascular disease, infection, autoimmune disease, and many other inflammatory conditions.
The important distinction is:
MMP-9 may provide information about inflammation, but it doesn’t tell us what caused the inflammation.
VEGF: Blood Flow and Oxygen Delivery
Vascular endothelial growth factor (VEGF) helps regulate blood vessels and the microcirculation and responds to changes in tissue oxygen availability.
Within the Shoemaker framework, some patients with CIRS demonstrate relatively low VEGF. This has led to the hypothesis that abnormalities in microcirculation and tissue oxygen delivery may contribute to symptoms such as fatigue, exercise intolerance, muscle discomfort, and cognitive dysfunction.
VEGF physiology is complicated, however. Many inflammatory and low-oxygen conditions actually increase VEGF. A low VEGF level by itself is therefore not diagnostic of CIRS or environmental illness.
MSH: Connecting the Brain and Immune System
One of the more unusual laboratory markers in the CIRS profile is alpha-melanocyte-stimulating hormone (MSH).
MSH is a signaling molecule involved in communication between the nervous, endocrine, and immune systems.
Within the Shoemaker model, persistently low MSH is thought to represent one of the downstream consequences of chronic inflammatory signaling.
MSH has been associated with regulation of:
sleep, pain perception, inflammation, pituitary function, and mucosal immunity.
This proposed neuroimmune disruption may help explain why patients with chronic inflammatory illnesses can experience symptoms involving many seemingly unrelated systems.
However, MSH is not routinely used in conventional medicine to diagnose environmental illness, and the CIRS-specific interpretation of MSH remains an evolving area of medicine.
ADH and Osmolality: Thirst and Frequent Urination
Antidiuretic hormone (ADH) helps determine how much water the kidneys retain.
When blood becomes more concentrated, serum osmolality rises and the brain normally releases more ADH. The kidneys then conserve water.
The normal relationship is:
Higher osmolality → increased ADH → greater water retention
Within the Shoemaker model, some patients demonstrate inappropriately low ADH relative to their serum osmolality.
This could theoretically contribute to frequent urination, excessive thirst, and difficulty maintaining normal water balance.
For this reason, ADH should generally be interpreted together with serum osmolality and sodium, rather than as an isolated laboratory value.
Abnormal ADH physiology also occurs in several well-established medical conditions, so significant abnormalities require appropriate conventional evaluation.
ACTH and Cortisol: The Stress-Response System
The CIRS evaluation may also include ACTH and cortisol.
These hormones form part of the body’s hypothalamic-pituitary-adrenal, or HPA, axis:
Brain → pituitary gland → ACTH → adrenal gland → cortisol
The Shoemaker model proposes that persistent inflammatory signaling may interfere with normal regulation of this system.
This does not mean that everyone with CIRS should have low cortisol. The proposed abnormality is better described as dysregulation, and different patterns may occur.
Because abnormalities of ACTH and cortisol can indicate important endocrine disorders, substantially abnormal results should always be evaluated using established endocrinologic principles rather than automatically attributed to CIRS.
VIP: Another Neuroimmune Messenger
Vasoactive intestinal peptide (VIP) is a small signaling molecule found throughout the brain, gastrointestinal tract, lungs, blood vessels, and immune system.
Despite its name, VIP does considerably more than regulate the intestine. It participates in blood-vessel regulation, gastrointestinal function, pulmonary function, inflammatory signaling, and communication between the nervous and immune systems.
Low VIP has been described within the Shoemaker CIRS model and plays a role in later stages of the Shoemaker treatment protocol.
As with MSH, however, low VIP is not independently established as a diagnostic marker for CIRS.
HLA-DR/DQ: Genetic Susceptibility
HLA-DR/DQ testing is different from the other CIRS laboratory tests because it examines genetics rather than current inflammation.
HLA molecules help the immune system recognize and present foreign material to immune cells.
The Shoemaker model proposes that certain HLA-DR/DQ combinations may make some individuals more susceptible to developing persistent inflammatory responses following particular environmental exposures.
The proposed relationship is:
Genetic susceptibility + environmental exposure → persistent immune activation
This has led to certain HLA patterns being described within the Shoemaker system as “mold susceptible,” “multisusceptible,” and other categories.
Having one of these HLA types does not mean that someone has CIRS. These genetic patterns also occur in healthy people, and the particular HLA classifications used within the Shoemaker system have not been broadly established as diagnostic genetic markers outside the CIRS framework.
Where GENIE Fits In
Another test sometimes used in evaluating CIRS is GENIE, which looks at gene expression.
GENIE is fundamentally different from HLA testing.
A helpful analogy is:
Your DNA is the instruction manual. Gene expression tells us which pages your cells are currently reading.
That gives us several different levels at which we can investigate the problem.
HLA-DR/DQ asks: What immune-response genes did you inherit?
GENIE asks: Which genes appear to be more or less active now?
C4a, TGF-β1, MMP-9, VEGF, MSH, VIP, ADH and the hormone tests ask: What measurable inflammatory, vascular, or neuroendocrine changes are occurring downstream?
Environmental testing, such as EnviroBiomics, asks an entirely different question: What organisms or microbial products can actually be detected in the environment?
Understanding these differences is important. A blood test showing an inflammatory response is not the same thing as demonstrating that a particular organism or toxin exists in someone’s home.
Putting the CIRS Picture Together
The overall hypothesis can be pictured as a sequence:
Water-damaged environment
↓
Mold, Actinobacteria, endotoxins and other microbial products
↓
Innate immune activation
↓
C4a • TGF-β1 • MMP-9
↓
Vascular and neuroendocrine changes
↓
VEGF • MSH • VIP • ADH/osmolality • ACTH/cortisol
Meanwhile, HLA genetics may influence susceptibility, while GENIE attempts to evaluate gene-expression patterns associated with the response.
This is why referring to all of these laboratory tests simply as “mold tests” or “biotoxin tests” isn’t quite accurate.
Most of them are measuring the body’s response rather than the environmental agent itself.
What These Tests Can, and Cannot, Tell Us
The molecules measured in the CIRS laboratory profile are real and biologically important. Complement proteins, cytokines, metalloproteinases, neuropeptides, and hormones all participate in normal human physiology and disease.
The more controversial question is whether a particular combination of these abnormalities can reliably establish CIRS caused by exposure to a water-damaged building.
Many of these markers are nonspecific and can be abnormal in other medical conditions. In addition, the particular diagnostic thresholds and patterns used within the Shoemaker protocol have not received the same degree of independent validation or broad acceptance as many conventional diagnostic tests.
For that reason, no single abnormal laboratory value should be considered proof that a patient has CIRS or that mold, Actinobacteria, or another environmental exposure is responsible for their symptoms.
Instead, these tests should be viewed as pieces of a larger puzzle that may include:
the patient’s symptoms and history, physical examination, conventional laboratory testing, environmental exposure history, and objective testing of the home or workplace when appropriate.
The goal is not simply to find an abnormal laboratory result. The goal is to determine whether the patient’s symptoms, environment, and biology fit together into a coherent clinical picture.
That distinction is particularly important in environmental medicine, where both extremes can be problematic. We should neither dismiss a patient’s illness simply because conventional testing is unrevealing nor assume that every abnormal inflammatory marker proves that a water-damaged building is responsible.
