Best investigation for diagnosing amyloidosis-
The diagnosis of amyloidosis may be suspected from the clinical signs and symptoms and from some of the findings mentioned; however, more specific tests must often be done for definitive diagnosis. Biopsy and subsequent Congo red staining is the most impoant tool in the diagnosis of amyloidosis. In general, biopsy is taken from the organ suspected to be involved. For example, renal biopsy is useful in the presence of urinary abnormalities. Rectal and gingival biopsy specimens contain amyloid in as many as 75% of cases with generalized amyloidosis. Examination of abdominal fat aspirates stained with Congo red is a simple, low-risk method. In suspected cases of AL amyloidosis, serum and urinary protein electrophoresis and immunoelectrophoresis should be performed. Bone marrow examination in such cases usually shows plasmacytosis, even if skeletal lesions of multiple myeloma are not present. Proteomic analysis of affected tissue is now being widely used for detection of small amounts of amyloid (from fat aspirates) and for definitive identification of the type of amyloid. Robbins 9 th edition page no. 158
Rectal biopsy
Colonoscopy
CT scan
Upper GI endoscopy
General pathology