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Amyloidosis is a group of disorders characterized by abnormal production and deposition of amyloid fibrils. Deposition distorts normal tissue architecture and impairs organ function.
The early symptoms of amyloidosis are often nonspecific (eg, weakness, fatigue, weight loss, edema, paresthesia). Macroglossia and periorbital edema are highly specific findings but are present in <20% of patients. Patients often present with renal disease, congestive heart failure, sensorimotor peripheral neuropathy, and orthostatic hypotension.
While biopsy of an affected organ (eg, kidney, heart, rectum, sural nerve) is almost always diagnostic, it is usually not necessary. Fat tissue is a common site of amyloid deposition in amyloidosis and is easily obtained by needle aspiration with minimal risk.
See Laboratory Approach to the Diagnosis of Amyloidosis and Laboratory Screening Tests for Suspected Multiple Myeloma in Special Instructions.
Demonstration of amyloid deposits as a practical procedure for the diagnosis of all forms of amyloidosis
Fat aspiration (FA) has a reported sensitivity of 72% and a specificity of 99% for amyloidosis.(2) If the degree of clinical suspicion for amyloidosis is high and the FA is negative, further investigation, including biopsy of an affected organ is indicated.
The laboratory will provide an interpretive report.
At least 3 to 6 particles of fat should be obtained for an adequate analysis.
This test provides a low yield and is therefore not recommended in evaluating patients with isolated peripheral neuropathy who have no other findings suggestive of amyloidosis.
Negative (reported as positive or negative)
1. Gertz MA, Rajkumar SV: Primary systemic amyloidosis. Curr Treat Options Oncol 2002 Jun;3(3):261-271
2. Gertz MA, Li CY, Shirahama T, Kyle RA: Utility of subcutaneous fat aspiration for the diagnosis of systemic amyloidosis (immunoglobulin light chain). Arch Intern Med 1988;148:929-933
3. Andrews TR, Colon-Otero G, Calamia KT, et al: Utility of subcutaneous fat aspiration for diagnosing amyloidosis in patients with isolated peripheral neuropathy. Mayo Clin Proc 2002;77:1278-1279