Lab studies for amyloidosis
What additional laboratory and imaging studies should be performed in amyloidosis?
• All patients with systemic amyloidosis should be evaluated for evidence of an associated plasma cell dyscrasia by ordering serum and urine protein electrophoresis and immunoelectrophoresis and free light chains. If all of these tests are negative, then it is unlikely that the amyloidosis is attributable to a plasma cell dyscrasia.
• In patients with symptoms consistent with a hereditary systemic amyloidosis, DNA analysis to identify the amyloidogenic variant protein should be performed.
• MRI or ultrasound of involved joints (especially shoulders): ultrasound showing rotator cuff >8 mm thick with echogenic deposits (sensitivity 72%, specificity 97%).
• Radiolabeled (I 123 ) SAP scintigraphy: if available, radioiodine-labeled SAP can be used for establishing extent of disease and monitoring response to therapy. Sensitivity is 90% for detecting AL and AA amyloid but only 48% for ATTR.
