{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T11:52:06Z","timestamp":1791287526262,"version":"4.1.0"},"reference-count":27,"publisher":"Croatian Society for Medical Biochemistry and Laboratory Medicine","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biochem. med. (Online)"],"published-print":{"date-parts":[[2026,10,15]]},"abstract":"<jats:p>Accurate measurement of serum electrolytes and calcium is essential for clinical management; however, monoclonal immunoglobulins, particularly IgM paraproteins, may cause misleading analytical interference. We report the case of an 85-year-old man admitted for low back pain whose serum sample showed marked inter-platform discordance in sodium and total calcium results. The Hitachi platform reported a \u201chypercalcemic crisis\u201d (total calcium 4.95 mmol\/L) and severe hyponatremia (125 mmol\/L), whereas the Beckman Coulter AU platform showed only mildly elevated total calcium (2.89 mmol\/L) and milder hyponatremia (133 mmol\/L). This corresponded to a 71.3% difference in total calcium, despite both platforms using the Arsenazo III method. Direct ion-selective electrode measurements excluded true hyponatremia and hypercalcemia. Dilution studies, polyethylene glycol precipitation, reaction-curve inspection, and simulation experiments confirmed that IgM-related precipitation and optical scattering were the underlying mechanisms. Specifically, platform-specific mixing dynamics determined the magnitude of interference. Recognition of biochemical-clinical discordance and targeted method comparison prompted hematological evaluation and led to a diagnosis of Waldenstr\u00f6m macroglobulinemia. This case highlights that unexplained analytical discrepancies may delay recognition of underlying disease if analytical interference is not appropriately investigated.<\/jats:p>","DOI":"10.11613\/bm.2026.030901","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T07:12:22Z","timestamp":1786691542000},"page":"548-554","source":"Crossref","is-referenced-by-count":0,"title":["Analytical interference by IgM paraprotein causing platform-dependent electrolyte discrepancies"],"prefix":"10.11613","volume":"36","author":[{"given":"Sheng","family":"Wang","sequence":"first","affiliation":[{"name":"The Third Clinical Medical College of China Three Gorges University, Gezhouba Central Hospital of Sinopharm, Yichang, Hubei, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoyong","family":"Duan","sequence":"additional","affiliation":[{"name":"The Third Clinical Medical College of China Three Gorges University, Gezhouba Central Hospital of Sinopharm, Yichang, Hubei, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yulin","family":"Zou","sequence":"additional","affiliation":[{"name":"The Third Clinical Medical College of China Three Gorges University, Gezhouba Central Hospital of Sinopharm, Yichang, Hubei, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianxiong","family":"Gui","sequence":"additional","affiliation":[{"name":"The Eighth Hospital of Wuhan, Wuhan, Hubei, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4885","published-online":{"date-parts":[[2026,10,15]]},"reference":[{"key":"key20260814071216_r1","doi-asserted-by":"crossref","first-page":"1061","DOI":"10.1002\/ajh.27666","article-title":"Waldenstr\u00f6m Macroglobulinemia: 2025 Update on Diagnosis, Risk Stratification, and Management.","volume":"100","author":"Gertz","year":"2025","journal-title":"Am J Hematol"},{"key":"key20260814071216_r2","article-title":"Waldenstr\u00f6m Macroglobulinemia - A State-of-the-Art Review: Part 1: Epidemiology, Pathogenesis, Clinicopathologic Characteristics, Differential Diagnosis, Risk Stratification, and Clinical Problems.","volume":"16","author":"Bibas","year":"2024","journal-title":"Mediterr J Hematol Infect Dis"},{"key":"key20260814071216_r3","doi-asserted-by":"crossref","DOI":"10.6004\/jnccn.2024.0001","article-title":"Waldenstr\u00f6m Macroglobulinemia\/Lymphoplasmacytic Lymphoma, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology.","volume":"22","author":"Kumar","year":"2024","journal-title":"J Natl Compr Canc Netw"},{"key":"key20260814071216_r4","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1111\/bjh.18036","article-title":"Diagnosis and management of Waldenstr\u00f6m macroglobulinaemia - A British Society for Haematology guideline.","volume":"197","author":"Pratt","year":"2022","journal-title":"Br J Haematol"},{"key":"key20260814071216_r5","doi-asserted-by":"crossref","first-page":"740","DOI":"10.1007\/s12185-025-03948-8","article-title":"JSH practical guidelines for hematological malignancies, 2023: II. 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