Understanding Lab Tests for Selective IgG Subclass Deficiency
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Selective IgG Subclass Deficiency is an immunodeficiency disorder characterized by low levels of one or more specific subclasses of Immunoglobulin G (IgG) antibodies. This condition can lead to recurrent infections, particularly of the respiratory tract, and requires specific blood testing for accurate diagnosis.
Recommended Test
IgG
This test measures immunoglobulin G levels in the blood, which is essential for diagnosing selective IgG subclass deficiency. When one or more subclasses of IgG are deficient, it leads to increased susceptibility to infections, particularly respiratory tract infections. This testing helps identify the specific immune deficiency and guides appropriate treatment strategies.
2907 reviews
What is Selective IgG Subclass Deficiency?
IgG antibodies are divided into four subclasses (IgG1, IgG2, IgG3, and IgG4), each playing different roles in immune protection. When one or more of these subclasses are deficient, the immune system's ability to fight certain types of infections becomes compromised, making individuals more susceptible to bacterial and viral infections.
Diagnosing Selective IgG Subclass Deficiency
Blood testing is the primary method for diagnosing this condition. Laboratory analysis measures the levels of different IgG subclasses to identify which ones are deficient. This testing is essential for patients with recurrent infections who may have normal total IgG levels but deficiencies in specific subclasses.
When to Consider Testing
Testing for selective IgG subclass deficiency should be considered in patients with recurrent sinusitis, pneumonia, or other respiratory infections, especially when these occur despite normal total immunoglobulin levels. Children with frequent ear infections or adults with chronic respiratory symptoms may benefit from this evaluation.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment. An immunologist or primary care physician can help interpret test results and develop an appropriate management plan.
