1. Introduction to Immunoglobulin G (IgG)

What is Immunoglobulin G (IgG)? Immunoglobulin G (IgG) is the most abundant antibody class in human blood, accounting for approximately 70–80% of total serum immunoglobulins. It plays a critical role in long-term immunity by neutralizing pathogens, opsonizing bacteria, and activating the complement system. IgG is essential for fighting bacterial and viral infections and is the only antibody that crosses the placenta, providing passive immunity to newborns. Measuring serum IgG levels is used to diagnose immune deficiencies, autoimmune diseases, chronic infections, and conditions like multiple myeloma.

2. What is an IgG Unit Converter?

Definition: The IgG Unit Converter converts serum IgG concentrations between various units, enabling standardization of laboratory results for clinical use.

Purpose: It assists clinicians and researchers in interpreting IgG levels across different measurement units (e.g., µmol/L to g/L), ensuring accurate diagnosis and monitoring of immune-related conditions.

3. Importance of IgG Unit Conversions

Converting IgG concentrations between units is critical for:

• Standardizing Results: Different labs report IgG in various units (e.g., g/L, mg/dL); conversion ensures consistency for diagnosis and treatment planning.
• Clinical Diagnosis: Accurate conversions aid in diagnosing primary and secondary immune deficiencies, autoimmune diseases, chronic infections, and monitoring conditions like multiple myeloma or liver disease.
• Research and Collaboration: Enables comparison of IgG data across studies or institutions using different measurement standards.

4. Clinical Significance

Elevated Levels: High IgG levels (>1600 mg/dL or >16 g/L in adults) may indicate:

• Chronic infections (e.g., hepatitis, HIV).
• Autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis).
• Multiple myeloma or monoclonal gammopathy (IgG type).
• Liver diseases (e.g., cirrhosis) or chronic inflammation.

Elevated IgG can contribute to immune complex-mediated tissue damage.

Low Levels: Low IgG levels (<700 mg/dL or <7 g/L in adults) may indicate:

• Primary immunodeficiencies (e.g., common variable immunodeficiency).
• Secondary immunodeficiencies (e.g., due to malnutrition, nephrotic syndrome, or immunosuppressive therapy).
• Protein-losing conditions (e.g., enteropathy, burns).

Low IgG increases susceptibility to recurrent infections.

Normal Ranges:

• Adults: Typically 700–1600 mg/dL (7–16 g/L or ~44–100 µmol/L, assuming an approximate molecular weight of 150 kDa).
• Children: Varies by age, generally lower (e.g., 300–900 mg/dL in infants).
• Values vary by lab, age, and assay—consult a healthcare provider for interpretation.

5. Precautions

Interferences:

• IgG levels can be influenced by acute infections, chronic inflammation, or medications (e.g., immunosuppressants); repeat testing may be needed for confirmation.
• Sample handling (e.g., proper storage, avoiding hemolysis) is critical to prevent degradation of immunoglobulins.
• Interpret IgG levels with other immunoglobulins (e.g., IgA, IgM), clinical symptoms, and diagnostic tests (e.g., serum protein electrophoresis, infection history)—consult a healthcare provider for accuracy.

6. Frequently Asked Questions (FAQ)

Q: Why are there different units for IgG?
A: Different units reflect varying standards; µmol/L is the SI unit, while g/L and mg/dL are commonly used in clinical practice for immunoglobulin measurements.

Q: What is a normal IgG level?
A: Normal serum IgG is typically 700–1600 mg/dL (7–16 g/L) in adults, varying by age. Consult a healthcare provider for interpretation.

Q: Can this converter be used for other immunoglobulins?
A: No, this converter is specific to IgG; other immunoglobulins (e.g., IgA, IgE) have different molecular weights and conversion factors—consult a healthcare provider for accuracy.