{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T21:38:04Z","timestamp":1773005884140,"version":"3.50.1"},"reference-count":17,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T00:00:00Z","timestamp":1771200000000},"content-version":"vor","delay-in-days":46,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Case Reports in Endocrinology"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:p>Phaeochromocytomas and paragangliomas (PPGLs) are catecholamine\u2010secreting neuroendocrine tumours (NETs) of the adrenal medulla and autonomic nervous system. Early recognition and management is critical given their potential morbidity and mortality. For this reason, stand\u2010alone screening investigations rely on a low diagnostic threshold, achieving high sensitivity at the relative cost of specificity. Following diagnosis, the only curative option is surgical removal of the tumour. Similar investigations are employed for postoperative surveillance. Persistent urinary normetanephrine elevation after curative phaeochromocytoma resection is rare and may lead to unnecessary investigations and anxiety. Our case highlights a previously underreported cause\u2014analytical interference from sulfasalazine\u2014and underscores the importance of considering medication effects in postoperative biochemical surveillance. We hereby present a 73\u2010year\u2010old Caucasian woman with a history of rheumatoid arthritis treated with sulfasalazine, hypertension, type 2 diabetes and hypothyroidism who exhibited persistently and significantly elevated urine normetanephrine, up to 15 months following successful surgical resection of a phaeochromocytoma. This was secondary to long\u2010term sulfasalazine use, causing gross interference with laboratory urine normetanephrine analysis without interfering with the serum normetanephrine value. Discontinuation of sulfasalazine normalised the urine normetanephrine results. This case identifies sulfasalazine as a clinically relevant source of urine normetanephrine assay interference, reinforcing the need for careful interpretation of biochemical diagnostic or surveillance results.<\/jats:p>","DOI":"10.1155\/crie\/6661577","type":"journal-article","created":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T10:05:27Z","timestamp":1771236327000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Sulfasalazine\u2010Induced Urinary Normetanephrine Elevation Mimicking Recurrent Phaeochromocytoma\u2014A Case Report"],"prefix":"10.1155","volume":"2026","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-0502-4390","authenticated-orcid":false,"given":"Maria","family":"Hadjicosti","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6157-2761","authenticated-orcid":false,"given":"Anastasia","family":"Papapostolou","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6156-2256","authenticated-orcid":false,"given":"Michail","family":"Papoulas","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-9339-8101","authenticated-orcid":false,"given":"Evdoxia","family":"Poulianiti","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-0110-4499","authenticated-orcid":false,"given":"Nikoleta","family":"Christodoulidou","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3562-8810","authenticated-orcid":false,"given":"Michalis K.","family":"Picolos","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2026,2,16]]},"reference":[{"key":"e_1_2_13_1_2","doi-asserted-by":"publisher","DOI":"10.1097\/00005792-199101000-00004"},{"key":"e_1_2_13_2_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMra1806651"},{"key":"e_1_2_13_3_2","doi-asserted-by":"publisher","DOI":"10.3390\/cancers14122942"},{"key":"e_1_2_13_4_2","doi-asserted-by":"publisher","DOI":"10.1007\/s12094-021-02622-9"},{"key":"e_1_2_13_5_2","doi-asserted-by":"publisher","DOI":"10.3390\/diagnostics13182940"},{"key":"e_1_2_13_6_2","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2010.1563"},{"key":"e_1_2_13_7_2","doi-asserted-by":"publisher","DOI":"10.1136\/bcr-2022-253597"},{"key":"e_1_2_13_8_2","doi-asserted-by":"publisher","DOI":"10.11613\/BM.2020.021003"},{"key":"e_1_2_13_9_2","doi-asserted-by":"publisher","DOI":"10.1159\/000321535"},{"key":"e_1_2_13_10_2","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2012-1548"},{"key":"e_1_2_13_11_2","doi-asserted-by":"publisher","DOI":"10.1097\/HJH.0000000000002438"},{"key":"e_1_2_13_12_2","doi-asserted-by":"publisher","DOI":"10.1373\/clinchem.2018.291369"},{"key":"e_1_2_13_13_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.trac.2016.01.027"},{"key":"e_1_2_13_14_2","doi-asserted-by":"publisher","DOI":"10.3389\/fendo.2024.1433582"},{"key":"e_1_2_13_15_2","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2018-01707"},{"key":"e_1_2_13_16_2","unstructured":"ClarkZ. BallochS. CaltonL. andMasonD. Interference Testing and Mitigation in Liquid Chromatography Tandem Mass Spectrometry Assays 2017 https:\/\/www.myadlm.org\/cln\/articles\/2017\/august\/interference-testing-and-mitigation-in-liquid-chromatography-tandem-mass-spectrometry-assays."},{"key":"e_1_2_13_17_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jchromb.2011.10.005"}],"container-title":["Case Reports in Endocrinology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1155\/crie\/6661577","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1155\/crie\/6661577","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1155\/crie\/6661577","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T19:19:49Z","timestamp":1772997589000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1155\/crie\/6661577"}},"subtitle":[],"editor":[{"given":"Kalyani","family":"Sen","sequence":"additional","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2026,1]]},"references-count":17,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,1]]}},"alternative-id":["10.1155\/crie\/6661577"],"URL":"https:\/\/doi.org\/10.1155\/crie\/6661577","archive":["Portico"],"relation":{},"ISSN":["2090-6501","2090-651X"],"issn-type":[{"value":"2090-6501","type":"print"},{"value":"2090-651X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1]]},"assertion":[{"value":"2025-10-14","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-01-22","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-02-16","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"6661577"}}