Examinations
Examinations
General Information:
Kappa light chains are components of immunoglobulins, proteins with antibody activity that specifically bind to antigens. Unlike most serum proteins produced in the liver, immunoglobulins are synthesized by plasma cells derived from B-lymphocytes in the bone marrow. Immunoglobulins are divided into five main classes—IgG, IgA, IgM, IgD, and IgE—with multiple subclasses. A polyclonal increase in immunoglobulins is a normal response to infections.
Monoclonal gammopathies refer to conditions where abnormal amounts of immunoglobulin are produced by plasma cells or B-lymphocytes (a clonal population derived from a single B-cell). These conditions may indicate benign or malignant diseases. Monoclonal gammopathy is detected by an abnormal band during serum or urine protein electrophoresis.
Immunoglobulins consist of structural units made of two identical heavy chains and two identical light chains (kappa or lambda). The type of heavy chain determines the immunoglobulin class. Immunoglobulins have constant and variable regions, the latter contributing to antigen specificity.
Monoclonal immunoglobulins produced by clonal cells have identical heavy and light chains. In electrophoresis, a large amount of monoclonal immunoglobulin migrates as a compact band in the gamma-globulin region, referred to as an M-peak, M-component, or paraprotein. This monoclonal immunoglobulin may appear as a polymer, monomer, or immunoglobulin fragment (light or heavy chain).
Free light chains (e.g., kappa chains) pass through the renal filter and can be detected in urine using electrophoresis.
The identification of monoclonal paraproteins is based on protein electrophoresis. Confirmation involves immunofixation, where specific polyvalent antisera are used to identify the immunoglobulin type. Quantitative analysis of paraproteins is conducted through densitometry. For full typing, electrophoresis and immunofixation are performed using a comprehensive panel of antisera against IgG, IgA, IgM, kappa, and lambda chains. The paraprotein class, concentration at diagnosis, and its progression over time are critical for diagnosis and prognosis. Paraproteins are markers of various hematological malignancies.
- Avoid alcohol for 24 hours before the test.
- Children under 1 year should not eat for 30–40 minutes before the test.
- Do not eat for 4 hours before the test; drinking non-carbonated water is allowed.
- Avoid physical and emotional stress for 30 minutes before the test.
- Do not smoke for 30 minutes before the test.
- Initial evaluation alongside serum electrophoresis and immunofixation in suspected monoclonal gammopathy (may replace urine electrophoresis for some clinical purposes except AL amyloidosis diagnosis).
- Prognosis, risk assessment, and monitoring in:
- Multiple myeloma.
- Solitary plasmacytoma.
- Non-secretory myeloma.
- Monoclonal gammopathy of undetermined significance (MGUS).
- AL amyloidosis.
- Screening for nephrotoxic levels of free kappa chains for early diagnosis of myeloma kidney.
Detection of Paraproteins:
Transient Paraproteinemia:
- Temporary monoclonal protein increase.
Benign Paraproteinemias:
- Monoclonal gammopathy of undetermined significance (MGUS).
Malignant Conditions:
- Multiple Myeloma.
- Waldenström’s Macroglobulinemia.
- Lymphomas and chronic lymphocytic leukemia (CLL).
- Heavy chain disease.
- Paraproteinemic polyneuropathy.
- Cryoglobulinemia.
- Cold hemolytic anemia.
- AL amyloidosis.
- POEMS syndrome.