Duodenal biopsy for diagnosis of renal involvement in amyloidosis

Amyloidosis results from extracellular deposition of a fibrillary protein in various organs, and renal biopsy is the best, but a complicated tool for diagnosis. Therefore, alternative biopsy sites have been proposed with varying degrees of sensitivity. We aimed to find the most appropriate biopsy site in patients with chronic kidney disease (CKD) in whom renal biopsy is contraindicated or unavailable. 42 patients (29 male; mean age 46 ± 16 y) with CKD in whom amyloidosis was suspected as the underlying etiology on clinical grounds, but renal biopsy was not available (Group I), and 36 patients (25 male; mean age 40 ± 16 y) with CKD in whom renal biopsy revealed AA-amyloidosis (Group II) were investigated. Upper and lower gastrointestinal tract (GIT) endoscopies were performed and multiple biopsies from gingiva, esophagus, antrum, duodenum and rectum were obtained. In Group I, no amyloidosis was detected in gingival and GIT biopsies among 13 patients. In the remaining 29 patients AA-amyloidosis was detected in various sites with the following frequencies: duodenum 100%, rectum 83%, antrum 79%, esophagus 44% and gingiva 29%. In Group II, frequency of amyloid deposition was 97% in duodenum, 76% each in antrum and rectum, 59% in esophagus and 32% in gingival mucosa. In conclusion, duodenal biopsy is sensitive for diagnosing amyloidosis in CKD patients, and highly correlates with renal amyloidosis.