====== IgG Kappa ======

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**IgG Kappa** refers to a subtype of [[immunoglobulin]] G (IgG) that contains **kappa light chains**. Immunoglobulins are antibodies produced by B cells of the immune system and play a crucial role in defending against infections.

### **Clinical Interpretation of IgG Kappa**
1. **Normal Physiology**:
   - Immunoglobulins consist of **heavy chains** and **light chains**.
   - There are two types of light chains: **kappa** and **lambda**.
   - Normally, there is a balanced ratio between **kappa and lambda** light chains.

2. **Increased IgG Kappa**:
   - May indicate a **clonal expansion** of plasma cells producing this specific immunoglobulin.
   - Commonly associated with **monoclonal gammopathies**, such as:
     - **IgG Kappa Multiple Myeloma**.
     - **Monoclonal Gammopathy of Undetermined Significance (MGUS)**.
     - **Waldenström's Macroglobulinemia**.
     - **B-cell Lymphoma**.

3. **Decreased IgG Kappa**:
   - May be seen in **immunodeficiencies**, such as **hypogammaglobulinemia** or **Common Variable Immunodeficiency (CVID)**.
   - Can also occur in disorders affecting antibody production, including certain **leukemias** or **lymphomas**.

4. **Kappa/Lambda Ratio**:
   - The **serum kappa-to-lambda light chain ratio** is an important diagnostic marker for monoclonal gammopathies.
   - A **high ratio** suggests **clonal proliferation of kappa-producing plasma cells**.
   - A **low ratio** suggests **lambda light chain dominance**, which can also indicate a plasma cell disorder.

### **When Is an IgG Kappa Test Ordered?**
- To evaluate **monoclonal gammopathies**.
- For **diagnosis and monitoring of multiple myeloma**.
- In assessing **immune deficiencies**.
- For detecting **lymphoproliferative disorders**.

If **IgG Kappa** levels are abnormal, additional tests may be needed, such as:
- **Serum protein electrophoresis (SPEP)**.
- **Immunofixation electrophoresis (IFE)**.
- **Serum free light chain assay (FLC)**.
- **Bone marrow biopsy** if multiple myeloma is suspected.