# Immunoglobulin G, Subclass 4

> This test measures the level of Immunoglobulin G Subclass 4 (IgG4), a specific type of antibody found in your blood. It helps doctors evaluate your immune system's function, particularly if you have recurrent sinus or lung infections, asthma, or are undergoing allergy therapy. This measurement helps identify immune deficiencies or abnormal immune responses that may be contributing to your symptoms. However, this test alone cannot diagnose specific allergies or confirm the presence of a specific immune disease.

- Labcorp code: 160531
- Category: [Allergies & Sensitivities](https://app.picardo.health/labs/tests/allergies-sensitivities.md)
- Price: shown at checkout, before payment.
- Blood draw: free at a Labcorp location, or $75.00 at home.
- Order link: https://app.picardo.health/labs/order?tests=160531&ref=assistant

## About ordering

A licensed physician reviews every order before any test is run, and results arrive in the person's Picardo account. Ordering is open to adults 18 and over in the US, except New York, New Jersey, Rhode Island, Pennsylvania, Maryland, Massachusetts, Hawaii and Maine. General health information, not medical advice.