Amyloidosis

Causes

Appropriate Tests

 

The definitive test to diagnosis amyloidosis is the demonstration of amyloid in a tissue biopsy, using special stains, Immunofluorescence (IF) and Electron microscopy (EM).
Ideally, biopsy of an affected organ (eg liver, kidney) should be performed. If no specific site can be identified, Colorectal biopsy or gingival biopsy may demonstrate amyloid.

Further tests may assist in determining nature and cause (see below):

Full blood count, C-Reactive protein or Erythrocyte sedimentation rate, Protein electrophoresis, Protein electrophoresis urine; Paraprotein typing; Free light chains; Immunoglobulins G, A, M; Bone marrow biopsy (aspiration and trephine). 

Creatinine urine, Urea urine, Protein urine to assess renal involvement.

Types of amyloidosis:

 

AL amyloid

Due to deposition of protein derived from immunoglobulin light chain fragments. Can occur alone or in association with Plasma cell myeloma, or less commonly, Lymphoma (non-Hodgkin). Tests Protein electrophoresis, Free light chains, Bone marrow biopsy (aspiration and trephine). 

AA amyloidosis

Due to deposition of amyloid A, an acute phase reactant, that can occur as a complication in chronic diseases with ongoing or recurring inflammation (eg, Rheumatoid arthritis, Inflammatory bowel disease, chronic infections). C-Reactive protein or Erythrocyte sedimentation rate.

Dialysis-related amyloidosis

Due to deposition of fibrils related to Beta-2-microglobulin in patients with chronic renal disease on dialysis.

Heritable amyloidosis

Heterogeneous groups of disorders due to heritable mutations leading to amyoid depositions. Molecular genetics testing.

Age-related (senile) systemic amyloidosis 

Deposition of otherwise normal transthyretin in myocardium and other tissues.

Organ specific amyloidosis

Amyloid deposition isolated to a single organ.