Amyloidosis Summary
Group of disorders associated with extracellular deposition of fibrils formed from low-molecular-weight proteins in a β-pleated sheet configuration
Diagnosis:
  1) clinical suspicion
  2) visualization of the protein
  3) characterization of the precursor
  4) identification of the extent of disease
Clinical Manifestations:
 • RENAL: Nephrotic syndrome -> Proteinuria, Can detect early if there is a "protein-albumin" dissociation in urine
 • CARDIAC: LVH, low-voltage EKG, & restrictive cardiomyopathy
 • GI: diarrhea. malabsorption, and pseudo-obstruction. Hepatosplenomegaly & hepatic failure. GI bleeding
 • NEURO: Orthostatic hypotension, autonomic neuropathy; neuropathy causing paresthesias, Ischemic stroke
 • BONE/JOINT: Amyloid arthropathy, Carpal tunnel syndrome
 • MUSCLES: Infiltration of muscles
 • SKIN: Periorbital purpura and macroglossia
 • NAILS: Dystrophy
 • HEME: ↓ activity of factor X, vascular Infiltration with amyloid
 • (AMYLOID ANGIOPATHY)
Diagnostic Testing:
 • Blood Tests:
    - SPEP with Serum immunofixation
    - Free light-chain assay, troponin, NT-proBNP
    - Creatinine, albumin, alkaline phosphatase, uric acid
 • Urine Tests:
    - UPEP with Urine Immunofixation
    - Tissue biopsy-Congo red
    - Amyloid typing
 • Cardiac Testing:
    - EKG
    - Echocardiogram with Doppler imaging: normal-size ventricles with disproportionate bi-atrial enlargement
    - MRI of the heart
 • GI Tests:
    - Diagnostic imaging of liver and spleen
    - Fecal fat measurements
    - Serum carotene levels
 • Nerve Tests:
    - Nerve conduction studies
    - Other: Serum amyloid P scintigraphy
  • Biopsies
    - Congo red:apple-green birefringence under polarized light microscopy
    - Immunohistochemical staining: Light-chain nature of the amyloid.

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