What is the reference range for Food-Specific Immunoglobulin G Subclass 4?

The standard reference range for Food-Specific Immunoglobulin G Subclass 4 is Lab-specific threshold; typically 50 elevated.. Reference ranges vary by laboratory and assay platform — interpret in context of the issuing laboratory's stated range.

Which tests measure Food-Specific Immunoglobulin G Subclass 4?

Food-Specific Immunoglobulin G Subclass 4 is measured in 1 test on BiomarkersLabs.com, including 198 Vegetarian Food Panel: IgA/IgG/IgG4.

Biomarker Reference · IgG4

What does the Food-Specific Immunoglobulin G Subclass 4 test measure?

Food-Specific Immunoglobulin G Subclass 4 (IgG4) is a clinical biomarker used in food-sensitivity-allergy assessment. IgG4 is the least abundant IgG subclass and has unique properties: it can form bispecific antibodies that do not fix complement or activate inflammatory pathways, which has led to the hypothesis that IgG4 reflects immunological tolerance rather than reactivity. It is measured in 1 laboratory test on BiomarkersLabs.com.

Reference Range: Lab-specific threshold; typically <20 AU negative, 20–50 borderline, >50 elevated.
Units: Arbitrary units (AU), Relative units
Measured In: 1 test
Category: Food Sensitivity

Functional medicine optimalReported as negative, borderline, or elevated by US BioTek; the meaning of 'optimal' is unclear for IgG4, as elevation may indicate tolerance rather than intolerance.

What is Food-Specific Immunoglobulin G Subclass 4?

IgG4 is the least abundant IgG subclass and has unique properties: it can form bispecific antibodies that do not fix complement or activate inflammatory pathways, which has led to the hypothesis that IgG4 reflects immunological tolerance rather than reactivity. In the context of allergen immunotherapy, rising IgG4 to allergens is associated with successful desensitisation. Elevated food-specific IgG4 may therefore indicate regular exposure and tolerance induction rather than adverse reaction, contradicting its use as a marker of food intolerance.

Why is Food-Specific Immunoglobulin G Subclass 4 measured?

Food-specific IgG4 is included in many food-sensitivity panels, but its interpretation is contested. Some functional practitioners view it as a marker of delayed hypersensitivity, while immunologists argue it reflects tolerance. Elevated IgG4 to a food commonly eaten may simply mean the immune system has adapted to it, and removing such foods based on IgG4 alone may be counterproductive.

Reference ranges

Standard reference: Lab-specific threshold; typically <20 AU negative, 20–50 borderline, >50 elevated.
Functional medicine optimal: Reported as negative, borderline, or elevated by US BioTek; the meaning of 'optimal' is unclear for IgG4, as elevation may indicate tolerance rather than intolerance.
Units: Arbitrary units (AU), Relative units

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.

Tests that measure Food-Specific Immunoglobulin G Subclass 4

1 test on BiomarkersLabs.com include this biomarker.

BML-FSA-015Comprehensive

198 Vegetarian Food Panel: IgA/IgG/IgG4

Food-Specific Immunoglobulin G Subclass 4 reference range in this test: Lab-specific threshold; typically <20 AU negative, 20–50 borderline, >50 elevated.

Related clinical conditions

Related Biomarkers

Frequently measured alongside

Food-Specific Immunoglobulin AIgA1 test Food-Specific Immunoglobulin GIgG1 test Vegetarian Food Reactivity ProfileReactivity Profile1 test

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