{"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":1788175188912,"version":"build-2803163510"},"reference-count":18,"publisher":"Walter de Gruyter GmbH","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"j_dx-2025-0150_abs_001\">\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To describe a case of a pseudohyponatremia secondary to hyperproteinemia in multiple myeloma and to emphasize the importance of analytical verification and laboratory-clinical collaboration to prevent diagnostic errors.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_dx-2025-0150_abs_002\">\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>A 55 year-old male presented with severe hyponatremia (119 mmol\/L) but paradoxically elevated serum osmolarity, suggesting that the hyponatremia might represent a laboratory artifact. Repeat serum sodium measurement by direct potentiometry with ion-specific electrodes yielded a normal value of 137 mmol\/L, confirming artifactual hyponatremia. Additional tests revealed marked hyperproteinemia due to an IgG-kappa monoclonal component, leading to the diagnosis of multiple myeloma.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_dx-2025-0150_abs_003\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>This case highlights the importance of artifacts in laboratory measurement, in this case recognizing analytical interferences when discordant hyponatremia is found. Confirmatory testing by direct potentiometry ion-specific electrodes prevents misdiagnosis and inappropriate therapy. Early identification of pseudohyponatremia further emphasizes the crucial role of the laboratory in ensuring accurate interpretation and optimizing patient management.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1515\/dx-2025-0150","type":"journal-article","created":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T07:56:35Z","timestamp":1768204595000},"page":"514-519","source":"Crossref","is-referenced-by-count":1,"title":["Spurious test results as a diagnostic clue \u2013 pseudohyponatremia revealing multiple myeloma"],"prefix":"10.1515","volume":"13","author":[{"given":"Francesca","family":"Pons-Vidal","sequence":"first","affiliation":[{"name":"Clinical Analysis and Clinical Biochemistry Department , Hospital Universitario Marqu\u00e9s de Valdecilla, Santander , Spain"},{"name":"Residents and Young Specialists Commission, Spanish Society of Laboratory Medicine (SEMEDLAB) , Madrid , Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Macarena","family":"Calvente de R\u00e1vena","sequence":"additional","affiliation":[{"name":"Clinical Analysis and Clinical Biochemistry Department , Hospital Universitario Marqu\u00e9s de Valdecilla, Santander , Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mar\u00eda","family":"Ortiz-Espejo","sequence":"additional","affiliation":[{"name":"Clinical Analysis and Clinical Biochemistry Department , Hospital Universitario Marqu\u00e9s de Valdecilla, Santander , Spain"},{"name":"Protein Biomarkers Commission, Spanish Society of Laboratory Medicine (SEMEDLAB) , Madrid , Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"374","published-online":{"date-parts":[[2026,1,13]]},"reference":[{"key":"2026083110583439953_j_dx-2025-0150_ref_001","doi-asserted-by":"crossref","unstructured":"Spasovski, G, Vanholder, R, Allolio, B, Annane, D, Ball, S, Bichet, D, et al.. 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