Laboratory findings in amyloidosis include elevated erythrocyte sedimentation rate, increased BUN level, serum creatinine, protein, casts, or fat bodies in urine. Serum troponin, B-type natriuretic peptide, and beta-2-microglobulin are prognostic markers for heart failure. Amyloid deposits can be identified histologically by Congo red staining and viewing under polarized light where amyloid deposits produce a distinctive ‘apple green birefringence’. Alternatively, thioflavin T stain may be used. An abdominal fat pad aspiration, rectal mucosa biopsy, or bone marrow biopsy can help confirm the diagnosis. They reveal positive findings in 80% patients.

• Cardiac biomarkers are the most important predictors of outcome in amyloidosis.
• They provide a quantitative assessment for cardiac damage and wall strain.^[1]
• The biomarkers include:

• Troponin I or Troponin T
• BNP and NT-proBNP

• Liver function tests, including:

• AST
• ALT
• Total bilirubin
• Alkaline phosphatase
• Albumin

• A variety of kidney function tests can suggest amyloidosis.
• These tests include abnormalities in:

• Serum creatinine
• Urinary protein
• Glomerular filtration rate
• Albumin to creatinine ratio in the urine

• Common tests that are abnormal in thyroidal involvement of amyloidosis include:

• TSH
• Free T4

• Concurrent multiple myeloma can be found in patients with amyloidosis.
• In such cases, laboratory testing should include^[2]:

• Serum protein electrophoresis
• Immunoglobulin levels
• Serum free light chains
• Beta-2-microglobulin