Standard Testing for Histamine Issues: Intolerance / MCAS
Blood Testing with Labcorp (can be added on to our standard panel)
Histamine, Plasma: $27
Measures circulating histamine levels (plasma preferred for accuracy, as whole blood can include basophil-released histamine). Elevated levels (>1–2 ng/mL or lab-specific cutoffs) suggest overload from poor breakdown, diet, or release. Useful for confirming excess histamine, especially if drawn during/near symptoms, but levels fluctuate rapidly (short half-life), so timing matters.
Tryptase, Serum: $85
Key to rule out mast cell disorders (MCAS or mastocytosis), which can mimic or overlap with HIT (both involve excess histamine release). Baseline tryptase >20 ng/mL or a rise >20% + 2 ng/mL from baseline during flares supports mast cell involvement. It’s highly specific for mast cells and helpful in differentiating histamine intolerance.
Precision Point Diagnostics Kit $329
Blood testing kit that needs to be ordered and takes up to 3 weeks to process. (Attached sample report)
DAO enzyme:
This tops the list as the most commonly ordered and discussed blood marker for HIT. DAO is the main enzyme that breaks down dietary histamine in the gut/intestines. Low activity (<10 U/mL in many labs, or <40–80 HDV depending on the assay) strongly supports reduced histamine degradation capacity, correlating with HIT symptoms in multiple studies. It’s often the first-line blood test recommended, though some research notes it’s not perfectly diagnostic alone (sensitivity/specificity varies, e.g., ~70–90% in discriminating HIT from controls in cohorts).
Histamine:
Same as above histamine, plasma description.
Zonulin:
Zonulin is a key biomarker for intestinal permeability (“leaky gut”), signaling loosened tight junctions in the gut lining that may allow toxins, bacteria, or food particles to enter the bloodstream, contributing to inflammation, immune activation, and histamine intolerance by impairing DAO function or promoting dysbiosis with histamine-producing bacteria.
LPS IgA, IgG, and IgM:
These markers assess intestinal permeability (“leaky gut”) by detecting immune responses to LPS that has translocated into the bloodstream due to a compromised gut barrier.
LPS IgA: Indicates a mucosal/secretory immune response (first-line defense at gut surfaces); elevated levels suggest increased permeability allowing LPS entry, contributing to local inflammation, systemic issues, or autoimmunity.
LPS IgG: Reflects a more mature, long-term systemic immune response; high levels signal ongoing exposure to leaked LPS, often linked to chronic inflammation, neuroinflammation, or conditions like depression, anxiety, or metabolic disorders.
LPS IgM: Represents an early/acute immune response; elevated IgM (especially with low IgG) may indicate recent or active bacterial overload without full seroconversion, while low overall IgM/IgA/IgG can point to immune suppression failing to control gut bacteria.
IMPORTANT: Histamine testing should be done during a flare or it may miss elevated levels.