Normal Reference Ranges
Adult
700 - 1600 mg/dL
Pediatric
Varies by age mg/dL
Clinical Significance
Primary antibody responsible for long-term humoral immunity. Significant reductions lead to recurrent sinopulmonary bacterial infections.
Causes of High
- Chronic infections
- Autoimmune disease (Lupus, RA)
- Multiple myeloma (IgG type)
- Chronic active hepatitis
Causes of Low
- Common variable immunodeficiency (CVID)
- Severe combined immunodeficiency (SCID)
- Protein-losing enteropathy
- Nephrotic syndrome