{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,8]],"date-time":"2026-06-08T11:32:30Z","timestamp":1780918350862,"version":"3.54.1"},"reference-count":38,"publisher":"The Endocrine Society","issue":"12","license":[{"start":{"date-parts":[[2025,5,2]],"date-time":"2025-05-02T00:00:00Z","timestamp":1746144000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,11,18]]},"abstract":"Abstract<\/jats:title>\n \n Context<\/jats:title>\n The biochemical diagnosis of carcinoid syndrome (CS) is established through the measurement of 24-hour urine 5-hydroxyindoleacetic acid (5-HIAA), but these measurements are prone to sampling error and may be troublesome for patients. Serum 5-HIAA measurements might constitute a more reliable and convenient alternative to diagnose CS.<\/jats:p>\n <\/jats:sec>\n \n Objective<\/jats:title>\n To assess the diagnostic value of serum 5-HIAA measurements in patients with CS.<\/jats:p>\n <\/jats:sec>\n \n Design<\/jats:title>\n Retrospective cohort study.<\/jats:p>\n <\/jats:sec>\n \n Setting<\/jats:title>\n Tertiary care hospital.<\/jats:p>\n <\/jats:sec>\n \n Patients<\/jats:title>\n 379 patients with a neuroendocrine tumor (NET), of whom 136 (35.9%) had CS; 153 control samples were included.<\/jats:p>\n <\/jats:sec>\n \n Intervention<\/jats:title>\n Paired serum and 24-hour urine 5-HIAA measurements.<\/jats:p>\n <\/jats:sec>\n \n Main Outcome Measure(s)<\/jats:title>\n Performance of serum and 24-hour urine 5-HIAA for the diagnosis of CS, measured by area under the receiver operating characteristic curve (AUROC).<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n Serum 5-HIAA performance was similar to that of 24-hour urine 5-HIAA for the diagnosis of CS in the total NET cohort (n = 379, AUROC 0.824 vs 0.843, P = .50) and in a subgroup of somatostatin analog (SSA)-na\u00efve patients (n = 141, AUROC 0.915 vs 0.938, P = .66). Optimal cutoff value of serum 5-HIAA for the diagnosis of CS was 139.4\u2005nmol\/L (sensitivity 96.3%, specificity 87.6%) as determined in a subgroup analysis of SSA-naive patients with CS and controls. Serum 5-HIAA correlated well with 24-hour urine 5-HIAA (r = 0.892, P &lt; .001) and the presence of flushing, diarrhea, and carcinoid heart disease (odds ratio 1.047-1.073 for every 100\u2005nmol\/L increase, P &lt; .001).<\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n Serum 5-HIAA measurements are equivalent to 24-hour urine 5-HIAA measurements for the diagnosis of CS in patients with NET and form an accessible alternative.<\/jats:p>\n <\/jats:sec>","DOI":"10.1210\/clinem\/dgaf263","type":"journal-article","created":{"date-parts":[[2025,4,30]],"date-time":"2025-04-30T19:26:39Z","timestamp":1746041199000},"page":"e3980-e3988","source":"Crossref","is-referenced-by-count":5,"title":["Serum 5-Hydroxyindoleacetic Acid Measurements for the Diagnosis and Follow-up of Carcinoid Syndrome"],"prefix":"10.1210","volume":"110","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-9501-1050","authenticated-orcid":false,"given":"Makarious","family":"Kerolles","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, Section of Endocrinology, ENETS Center of Excellence, Erasmus Medical Center Cancer Institute , 3015 GD Rotterdam ,","place":["The Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4590-5925","authenticated-orcid":false,"given":"Merijn C F","family":"Mulders","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Section of Endocrinology, ENETS Center of Excellence, Erasmus Medical Center Cancer Institute , 3015 GD Rotterdam ,","place":["The Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9404-2903","authenticated-orcid":false,"given":"Mina","family":"Mirzaian","sequence":"additional","affiliation":[{"name":"Department of Clinical Chemistry, Erasmus Medical Center , 3015 GD Rotterdam ,","place":["The Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5937-7505","authenticated-orcid":false,"given":"Sjoerd A A","family":"van den Berg","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Section of Endocrinology, ENETS Center of Excellence, Erasmus Medical Center Cancer Institute , 3015 GD Rotterdam ,","place":["The Netherlands"]},{"name":"Department of Clinical Chemistry, Erasmus Medical Center , 3015 GD Rotterdam ,","place":["The Netherlands"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2319-391X","authenticated-orcid":false,"given":"Richard A","family":"Feelders","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Section of Endocrinology, ENETS Center of Excellence, Erasmus Medical Center Cancer Institute , 3015 GD Rotterdam ,","place":["The Netherlands"]},{"name":"Department of Endocrinology, Diabetes and Metabolism, New York University Langone Medical Center , New York, NY 10017 ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1463-5165","authenticated-orcid":false,"given":"Wouter W","family":"de Herder","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Section of Endocrinology, ENETS Center of Excellence, Erasmus Medical Center Cancer Institute , 3015 GD Rotterdam ,","place":["The 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