IMMUNOGLOBULIN G4 (IgG4) - SERUM TEST
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Turnaround Time: 3rd Working Day | Sample: Blood (Serum) | Home Collection: Available
Immunoglobulin G4 (IgG4) is a unique subclass of antibodies often linked to systemic inflammatory conditions. The IgG4 test is primarily used to diagnose IgG4-Related Disease (IgG4-RD), a condition causing fibro-inflammatory masses in organs like the pancreas, salivary glands, and lymph nodes. It is also used in specific allergy immunotherapy monitoring.
What is Immunoglobulin G4 (IgG4)?
Immunoglobulins (antibodies) are proteins made by your immune system to fight infection. IgG is the most abundant type, but it has four subclasses: IgG1, IgG2, IgG3, and IgG4.
IgG4 is the least common subclass, making up less than 5% of total IgG. However, it behaves differently from the others. While most antibodies trigger inflammation to kill bacteria, IgG4 often acts as a blocker or regulator, dampening immune responses. In rare cases, the body produces too much of it, leading to a condition where immune cells invade organs and cause scarring (fibrosis).
Why is the IgG4 Test Performed?
This test is a specialized diagnostic tool used for specific autoimmune and inflammatory conditions. It is NOT a routine blood test.
1. Diagnosing IgG4-Related Disease (IgG4-RD)
This is the primary use of the test. IgG4-RD is a systemic condition where immune cells infiltrate organs, causing them to enlarge and harden. Common manifestations include:
- Autoimmune Pancreatitis (Type 1): Inflammation of the pancreas, mimicking pancreatic cancer.
- Mikulicz Disease: Enlargement of salivary and lacrimal (tear) glands.
- Retroperitoneal Fibrosis: Scar tissue buildup in the back of the abdomen, potentially blocking the ureters.
- Thyroiditis: Riedel's thyroiditis (hard, fibrotic thyroid).
2. Allergy & Immunotherapy
IgG4 levels naturally rise when a person undergoes immunotherapy (allergy shots). In this context, high IgG4 is actually a good sign it indicates that the body is developing tolerance to the allergen (e.g., bee venom or pollen) and blocking the allergic IgE reaction.
Symptoms of IgG4-Related Disease
Since this disease can affect almost any organ, symptoms vary widely. However, patients often present with:
- Painless swelling of lymph nodes, glands, or organs.
- Jaundice (yellowing of skin) if the pancreas or bile ducts are affected.
- Dry eyes and dry mouth (if salivary glands are involved).
- Abdominal or back pain.
- Unexplained weight loss.
How to Prepare for the Test
Preparation is simple and standard for most immunology tests:
- Fasting: No fasting is required. You can eat and drink normally.
- Medications: Steroids (like Prednisone) can drastically lower IgG4 levels. If you are already on steroids, inform your doctor, as the test results might be falsely low.
- Sample Collection: A standard blood draw from a vein in your arm.
Interpreting Test Results
Normal Range: Generally, serum IgG4 levels should be < 135 mg/dL (ranges vary by lab).
| Result Level | Possible Interpretation |
|---|---|
| Normal | Unlikely to have active IgG4-Related Disease (though biopsy may still be needed). |
| Mild Elevation (135 - 270 mg/dL) | Can be seen in allergies, parasitic infections, or other autoimmune conditions. Not diagnostic on its own. |
| High Elevation (> 270 mg/dL) | Strongly suggestive of IgG4-Related Disease, especially if accompanied by organ swelling. |
Treatment for High IgG4
If diagnosed with IgG4-Related Disease, treatment is usually effective and may include:
- Corticosteroids: The first line of defense to reduce inflammation quickly.
- Immunosuppressants: Drugs like Rituximab that deplete B-cells are used if steroids fail or for long-term management.
- Monitoring: Serial IgG4 testing is done to monitor response to treatment. Levels should drop as the disease goes into remission.
Frequently Asked Questions (FAQs)
Technically, they measure the same antibody, but the clinical application differs. The Serum IgG4 test (Total IgG4) is a medically accepted diagnostic tool for autoimmune diseases. IgG Food Sensitivity Panels (Specific IgG4) are widely sold but generally not recommended by allergy societies for diagnosing food triggers.
Yes. A significant minority of patients have normal blood levels despite having the disease in their tissues. A biopsy is often the gold standard for confirmation.
This is a specialized immunology test. Sanovra Lab provides reports by the 3rd Working Day.
Samples can be collected, but processing usually happens on working days. The turnaround time excludes Sundays.
The market price is typically around ₹6400 or higher due to the reagents involved. We offer a discounted price of ₹5899.
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Disclaimer: The information provided here is for educational purposes only and does not constitute medical advice. Laboratory results should always be interpreted by a qualified Doctor in the context of clinical findings.