From the Guidelines
In an acute kidney injury (AKI) screen, testing for ANCA, ANA, immunoglobulins, and Bence Jones protein is crucial for identifying underlying causes of kidney damage, particularly when autoimmune or hematologic disorders are suspected, as supported by the KDIGO 2024 clinical practice guideline for the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis 1. The value of these tests lies in their ability to diagnose specific conditions that can cause rapid kidney deterioration.
- ANCA testing is vital for diagnosing vasculitis conditions like granulomatosis with polyangiitis or microscopic polyangiitis.
- ANA testing helps identify systemic lupus erythematosus and other autoimmune conditions affecting the kidneys.
- Immunoglobulin levels can reveal disorders like multiple myeloma or monoclonal gammopathy.
- Bence Jones protein (free light chains in urine) specifically indicates plasma cell disorders that can cause kidney damage through light chain deposition or cast nephropathy. These tests should be ordered when clinical presentation suggests an inflammatory, autoimmune, or plasma cell disorder rather than more common AKI causes like dehydration, medication toxicity, or urinary obstruction, as emphasized in the ACR Appropriateness Criteria for renal failure 1. The results guide treatment decisions, as immunosuppressive therapy may be needed for autoimmune causes, while plasma cell disorders require specific hematologic interventions, highlighting the importance of accurate diagnosis in AKI management, also discussed in recommendations on acute kidney injury biomarkers from the Acute Disease Quality Initiative Consensus Conference 1. It is essential to consider the limitations and potential applications of biomarkers in AKI diagnosis and management, as noted in the definition of acute kidney injury and its use in practice 1, and the description of common biomarkers of AKI 1.
From the Research
ANCA, ANA, Immunoglobulins, and Bence Jones Protein in AKI Screen
- ANCA (Anti-Neutrophil Cytoplasmic Antibodies) are a group of autoantibodies involved in the pathogenesis of several autoimmune disorders, including granulomatosis with polyangiitis and microscopic polyangiitis 2.
- ANA (Antinuclear Antibodies) are a hallmark of systemic autoimmune diseases and are used as a criterion for classification and diagnosis of these diseases, including systemic lupus erythematosus and juvenile idiopathic arthritis 3.
- Immunoglobulins are a type of antibody that plays a crucial role in the immune system, and abnormalities in immunoglobulin levels can be indicative of various diseases, including multiple myeloma and autoimmune disorders 4, 5.
- Bence Jones proteins are abnormal immunoglobulin light chains that are excreted in the urine of patients with multiple myeloma and other plasma cell disorders, and can be used as a diagnostic marker for these diseases 6, 4.
Clinical Implications
- The presence of ANCA, ANA, and abnormal immunoglobulin levels can be indicative of underlying autoimmune or plasma cell disorders, and can be used to guide diagnosis and treatment 2, 3, 5.
- Bence Jones proteins can be used to monitor disease activity and response to treatment in patients with multiple myeloma and other plasma cell disorders 6, 4.
- The detection of these proteins and antibodies can be an important part of an AKI (Acute Kidney Injury) screen, as they can be indicative of underlying diseases that may be contributing to kidney damage 2, 3, 5.
Laboratory Tests
- Indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA) can be used to detect ANCA and ANA 2, 3.
- Immunoelectrophoresis and immunodiffusion can be used to detect and characterize immunoglobulins and Bence Jones proteins 6, 4.
- Urine protein electrophoresis can be used to detect Bence Jones proteins in the urine 6, 4.