What are the diagnostic criteria for amyloidosis?

From the Guidelines

The diagnostic criteria for amyloidosis involve a combination of clinical clues, tissue biopsy, and laboratory tests to confirm the presence of amyloid deposits and identify the type of amyloidosis.

Diagnostic Approach

• Clinical clues for amyloidosis include restrictive cardiomyopathy, macroglossia, unexplained proteinuria, hepatomegaly, and acquired factor X deficiency with coagulopathy 1.
• Tissue biopsy is essential for diagnosis, with options including biopsy of the affected organ, bone marrow, or abdominal fat aspiration 1.
• Laboratory tests, such as serum free light chains, serum immunofixation electrophoresis (IFE), and urine IFE, can help identify the type of amyloidosis 1.

Histological Diagnosis

• Histological diagnosis of cardiac amyloidosis can be made by endomyocardial biopsy with Congo red staining and typing by immunohistochemistry and/or mass spectrometry 1.
• Extracardiac biopsy can also be used to diagnose cardiac amyloidosis, with typical cardiac imaging features and abnormal cardiac biomarkers supporting the diagnosis 1.

Typing of Amyloidosis

• Mass spectrometry-based analysis is the gold standard for typing amyloidosis, with a reported sensitivity of 88% and specificity of 96% 1.
• Immunohistochemistry and immunogold electron microscopy can also be used to type amyloidosis, but are less sensitive and specific than mass spectrometry 1.

Clinical Diagnosis

• Clinical diagnosis of cardiac amyloidosis can be made using a combination of clinical clues, laboratory tests, and imaging studies, such as echocardiography and cardiac magnetic resonance (CMR) 1.
• The diagnosis of cardiac amyloidosis should be considered in patients with unexplained heart failure, particularly those with preserved ejection fraction, and in patients with monoclonal gammopathy of undetermined significance (MGUS) 1.

From the Research

Diagnostic Criteria for Amyloidosis

The diagnostic criteria for amyloidosis involve a combination of clinical suspicion, laboratory tests, and tissue biopsy. The following are some key points to consider:

• Amyloidosis is a heterogeneous group of disorders characterized by the deposition of abnormally folded proteins in tissues, leading to organ damage 2.
• The diagnosis of amyloidosis requires the identification of amyloid deposits in tissues, which can be done through biopsy and histological examination 3, 4.
• The type of amyloid protein involved is crucial in determining the diagnosis and treatment of amyloidosis, with different types of amyloidosis having distinct clinical features and treatment options 2, 3.
• Cardiac amyloidosis can be diagnosed non-invasively using imaging techniques such as echocardiography, cardiovascular magnetic resonance imaging, and radionuclide imaging, but tissue biopsy is still essential for confirming the diagnosis and determining the type of amyloid protein involved 5, 3, 4.
• The clinical manifestations of amyloidosis can be non-specific, making early diagnosis challenging, and requiring a high index of suspicion and thorough evaluation 6.

Methods for Diagnosing Amyloidosis

The following methods can be used to diagnose amyloidosis:

• Tissue biopsy: This is the gold standard for diagnosing amyloidosis, and involves the examination of tissue samples under a microscope to identify amyloid deposits 3, 4.
• Imaging techniques: These can be used to diagnose cardiac amyloidosis and other forms of amyloidosis, and include echocardiography, cardiovascular magnetic resonance imaging, and radionuclide imaging 5.
• Laboratory tests: These can be used to identify the type of amyloid protein involved and to monitor the progression of the disease 2, 3.
• Laser capture microdissection and tandem mass spectrometry (LCM-MS): This is a technique that can be used to identify the amyloidogenic protein and determine the type of amyloidosis 3.