{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T11:19:48Z","timestamp":1788175188932,"version":"build-2803163510"},"reference-count":8,"publisher":"Walter de Gruyter GmbH","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"Abstract<\/jats:title>\n \n Objectives<\/jats:title>\n AL amyloidosis is a rare disorder caused by deposition of misfolded immunoglobulin light chains as amyloid fibrils in vital body organs. The diagnosis requires a triad: identification of a monoclonal protein (via serum\/urine studies), histological confirmation of amyloid deposits and clinical evidence of organ dysfunction. Serum protein electrophoresis (SPEP) and immunofixation (SIFE) are first-line tests but fail to detect monoclonal proteins in 10\u201320\u202f% of cases, particularly those with low plasma cell burden or rapid renal excretion of FLCs. Serum free light chain (FLC) assays and urine immunofixation (UIFE) are indispensable in such scenarios but tissue biopsy remains the diagnostic cornerstone.<\/jats:p>\n <\/jats:sec>\n \n Case presentation<\/jats:title>\n We discuss a 67-year-old man who presented with a 4-month history of progressive bilateral lower limb edema, fatigue and frothy urine. Initial evaluation revealed nephrotic-range proteinuria. SPEP and SIFE showed no monoclonal bands. X-ray skull revealed multiple punched-out lytic lesions, raising suspicion of an underlying plasma cell dyscrasia. UIFE identified a monoclonal lambda light chain. Renal biopsy confirmed amyloid deposition. The\u00a0patient was initiated on bortezomib-dexamethasone chemotherapy, targeting the plasma cell clone to halt amyloid production.<\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n This case underscores the diagnostic challenges of AL amyloidosis, particularly in serum-negative presentations with low tumor burden. Role of UIFE was pivotal in detecting monoclonal lambda light chains excreted via the kidneys, overcoming the limitations of serum-based assays. The absence of serum monoclonal proteins in early-stage disease mandates a multimodal approach: integrating clinical suspicion (e.g., nephrotic syndrome, cardiomyopathy, or neuropathy in older adults), urine studies, serum FLC assays, and targeted biopsies.<\/jats:p>\n <\/jats:sec>","DOI":"10.1515\/dx-2025-0062","type":"journal-article","created":{"date-parts":[[2025,9,18]],"date-time":"2025-09-18T20:05:08Z","timestamp":1758225908000},"page":"524-530","source":"Crossref","is-referenced-by-count":0,"title":["Unmasking amyloid light-chain amyloidosis through biochemical lens: diagnostic utility of urine immunofixation in serum-negative cases"],"prefix":"10.1515","volume":"13","author":[{"given":"Lekha priyadharshini","family":"Kamarajan","sequence":"first","affiliation":[{"name":"Department of Biochemistry , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ravi Ranjan","family":"Kumar Suman","sequence":"additional","affiliation":[{"name":"Department of Biochemistry , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rajeev","family":"Ranjan","sequence":"additional","affiliation":[{"name":"Department of Biochemistry , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sushil","family":"Kumar","sequence":"additional","affiliation":[{"name":"Biochemistry , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amresh","family":"Krishna","sequence":"additional","affiliation":[{"name":"Department of Nephrology , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0445-6972","authenticated-orcid":false,"given":"Mala","family":"Mahto","sequence":"additional","affiliation":[{"name":"Biochemistry , AIIMS Patna , Patna , Bihar , India"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"374","published-online":{"date-parts":[[2025,9,16]]},"reference":[{"key":"2026083110583441875_j_dx-2025-0062_ref_001","doi-asserted-by":"crossref","unstructured":"Reilly, JB, Myers, JS, Salvador, D, Trowbridge, RL. Use of a novel, modified fishbone diagram to analyze diagnostic errors. Diagnosis 2014;1:167\u201371. https:\/\/doi.org\/10.1515\/dx-2013-0040.","DOI":"10.1515\/dx-2013-0040"},{"key":"2026083110583441875_j_dx-2025-0062_ref_002","unstructured":"Palladini, G, Merlini, G, Obici, L, Milani, P, Foli, A, Lavatelli, F, et al.. Monoclonal gammopathy of undetermined significance (MGUS) and amyloidosis: a perspective. Blood 2012;120:1560\u20136. https:\/\/doi.org\/10.1182\/blood-2012-02-343021."},{"key":"2026083110583441875_j_dx-2025-0062_ref_003","unstructured":"Dispenzieri, A, Gertz, MA, Kyle, RA, Larson, DR, Therneau, TM, Kumar, SK, et al.. The role of free light chains in diagnosis of AL amyloidosis. Semin Hematol 2015;52:52\u20138. https:\/\/doi.org\/10.1053\/j.seminhematol.2014.12.001."},{"key":"2026083110583441875_j_dx-2025-0062_ref_004","unstructured":"Skinner, M, Sanchorawala, V, Seldin, DC, Quillen, K, Berk, JL, Dember, LM, et al.. Early diagnosis and treatment of AL amyloidosis. Nephrol Dial Transplant 2015;30:739\u201347. https:\/\/doi.org\/10.1093\/ndt\/gfu479."},{"key":"2026083110583441875_j_dx-2025-0062_ref_005","unstructured":"Buxbaum, JN, Ikeda, SI. Amyloidosis and the nervous system. Neurotherapeutics 2017;14:741\u201350. https:\/\/doi.org\/10.1007\/s13311-017-0545-1."},{"key":"2026083110583441875_j_dx-2025-0062_ref_006","unstructured":"Gertz, MA, Lacy, MQ, Dispenzieri, A, Hayman, SR, Kumar, SK, Buadi, FK, et al.. AL amyloidosis: a disease of paraproteinemia. J\u00a0Clin Oncol 2011;29:3445\u201352. https:\/\/doi.org\/10.1200\/JCO.2011.36.5419."},{"key":"2026083110583441875_j_dx-2025-0062_ref_007","doi-asserted-by":"crossref","unstructured":"Linos, A, Shlipak, MG, Katz, R, Estrella, MM, Ix, JH, Rifkin, DE, et al.. Renal amyloidosis in elderly patients: diagnosis and management. Am J Kidney Dis 2017;70:505\u201312. https:\/\/doi.org\/10.1053\/j.ajkd.2017.04.006.","DOI":"10.1053\/j.ajkd.2017.04.006"},{"key":"2026083110583441875_j_dx-2025-0062_ref_008","unstructured":"Sanchorawala, V, Skinner, M, Quillen, K, Berk, JL, Seldin, DC, Dember, LM, et al.. AL amyloidosis: diagnosis and treatment. Semin Hematol 2014;51:113\u201321. https:\/\/doi.org\/10.1053\/j.seminhematol.2014.01.002."}],"container-title":["Diagnosis"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.degruyterbrill.com\/document\/doi\/10.1515\/dx-2025-0062\/xml","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.degruyterbrill.com\/document\/doi\/10.1515\/dx-2025-0062\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T10:59:20Z","timestamp":1788173960000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.degruyterbrill.com\/document\/doi\/10.1515\/dx-2025-0062\/html"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,16]]},"references-count":8,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,9,2]]},"published-print":{"date-parts":[[2026,9,1]]}},"alternative-id":["10.1515\/dx-2025-0062"],"URL":"https:\/\/doi.org\/10.1515\/dx-2025-0062","relation":{},"ISSN":["2194-8011","2194-802X"],"issn-type":[{"value":"2194-8011","type":"print"},{"value":"2194-802X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,16]]}}}