Coombs Test

Introduction

The Coombs test, also known as the antiglobulin test, is a diagnostic tool used to detect antibodies or complement proteins bound to the surface of red blood cells (RBCs). It is widely used in both human and veterinary medicine to diagnose conditions such as immune-mediated hemolytic anemia (IMHA) and other immune-related disorders.

Key Insights

Diagnostic Utility in Hemolytic Anemia:
- The Coombs test is essential for distinguishing immune from non-immune hemolytic disorders, although a negative result does not rule out an immune process .
- In veterinary medicine, the test is used to diagnose IMHA, with techniques such as using monovalent reagents and testing at different temperatures to improve sensitivity .
Positive Coombs Test in Various Conditions:
- Acute leukemia: A positive Coombs test can occur at diagnosis or during remission, often involving complement type antibodies.
- Hodgkin's disease: Coombs positivity is associated with advanced disease and the presence of IgG anti-It antibodies.
- Lead poisoning: Both human and experimental lead poisoning in dogs can result in a positive Coombs test, often linked to immature erythrocytes .
Factors Affecting Test Sensitivity:
- The sensitivity of the Coombs test can be influenced by the type of reagents used, the temperature at which the test is conducted, and the presence of a prozone effect .
- False-positive and false-negative results can occur, necessitating the use of more sensitive technologies like flow cytometry .
Application in Immune Thrombocytopenia:
- The Coombs test can detect IgG and C3 on platelets, aiding in the diagnosis and management of immune thrombocytopenia.

Conclusion

The Coombs test is a valuable diagnostic tool for identifying immune-related hemolytic disorders and other conditions such as leukemia, Hodgkin's disease, and lead poisoning. Its sensitivity can be enhanced through various techniques, although false results are possible. The test's application extends beyond RBCs to platelets, demonstrating its versatility in diagnosing immune-mediated conditions.

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Beyond the Coombs test.

The Coombs test is not the only tool available to distinguish immune from nonimmune hemolytic disorders.

Positive Coombs test in acute leukaemia

A positive Coombs test is common in acute leukaemia patients, but its relationship with FAB morphologic subtype, immune abnormalities, or leukemia course remains unclear.

Coombs' testing and its diagnostic significance in dogs and cats.

Coombs' test can aid in diagnosing IMHA in dogs and cats, but its sensitivity can be improved through monovalent reagents, increased dilutions, and testing at 4°C.

Immune thrombocytopenia. Use of a Coombs antiglobulin test to detect IgG and C3 on platelets.

The radiolabeled Coombs antiglobulin test effectively diagnoses and manages immune platelet disorders, revealing increased IgG levels on platelets in idiopathic thrombocytopenic purpura patients and a role for C3 in the pathogenesis.

Pattern of Coombs' test reactivity has diagnostic significance in dogs with immune-mediated haemolytic anaemia.

The pattern of Coombs' test reactivity in dogs with immune-mediated haemolytic anaemia differs significantly from those with concurrent/underlying diseases, making it crucial for diagnosis.

Factors Affecting the Speed of Agglutination in the Coombs Test

The Coombs test is a sensitive method for detecting incomplete antibodies, but optimal conditions are needed for maximum sensitivity.

Positive Coombs test in Hodgkin's disease: significance and implications.

A positive Coombs test in Hodgkin's disease patients suggests active and advanced disease, with IgG anti-It potentially representing a unique antibody in Coombs-positive hemolytic anemia.

The direct Coombs test in lead poisoning.

The direct Coombs test is positive in lead poisoning cases, with a layer phenomenon in dogs' blood and potential correlation with cell immaturity or chemical trauma to the membrane.

The Coombs' test in veterinary medicine: past, present, future.

The Coombs' test is a useful tool in veterinary medicine for diagnosing immune-mediated hemolytic anemia, but its sensitivity in both human and veterinary medicine has led to the development of more sensitive technologies.

The Direct Coombs Test and Reticulocytes *

The Coombs antiglobulin test can detect reticulocytes, suggesting a non-immunologic mechanism for its development in certain conditions.

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