{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T18:50:59Z","timestamp":1787856659240,"version":"build-2784847793"},"reference-count":22,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2026,1,7]],"date-time":"2026-01-07T00:00:00Z","timestamp":1767744000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,5,5]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Tacrolimus therapeutic drug monitoring is a routine and critical assay for managing transplant patients. Tacrolimus can be measured from whole blood samples via liquid chromatography\u2013tandem mass spectrometry (LC-MS\/MS) or immunoassay (IA). LC-MS\/MS provides accurate parent drug quantification with minimal metabolite interference but requires expensive analyzers, highly trained staff, and is often a very manual process. Immunoassays offer faster, simpler workflows, but historically have been prone to significant cross-reaction with the drug\u2019s metabolites or other therapeutic drugs, leading to a falsely elevated result. Newer immunoassays show promising improvements in specificity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Using 73 residual patient samples, we compared our in-house LC-MS\/MS tacrolimus assay to the Roche Elecsys\u00ae tacrolimus electrochemiluminescence immunoassay on the cobas\u00ae e801 analyzer. Comparative analysis was done with Deming regression and Bland\u2013Altman comparison. Linearity, within-individual imprecision, and total imprecision post immunoassay implementation were also evaluated, along with changes and improvements to workflow and turnaround times (TAT).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The Roche Elecsys tacrolimus assay correlated well with our LC-MS\/MS method (Deming regression equation: y = 1.004x + 0.4848). The bias was 0.52\u2005ng\/mL (an average of 8.1%) as determined by Bland\u2013Altman comparison. When switching to the immunoassay we observed a 42%\u201351% improvement in TAT across the median, 75th percentile, and 90th percentile.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>We observed excellent correlation between the Roche Elecsys tacrolimus assay on an e801 analyzer vs our in-house LC-MS\/MS assay, with good precision and linearity across reportable ranges. Changing from mass spectrometry to tacrolimus immunoassay substantially improved our TAT and workflow.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/jalm\/jfaf199","type":"journal-article","created":{"date-parts":[[2025,12,9]],"date-time":"2025-12-09T13:09:33Z","timestamp":1765285773000},"page":"531-541","source":"Crossref","is-referenced-by-count":4,"title":["Tacrolimus Assay Comparison: Analytical and Operational Considerations for Immunoassay vs Mass Spectrometry Testing in a High Volume Clinical Laboratory"],"prefix":"10.1093","volume":"11","author":[{"given":"Rebekah","family":"Goldblatt","sequence":"first","affiliation":[{"name":"TriCore Reference Laboratories , Albuquerque, NM ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Florencia","family":"Monge","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of New Mexico , Albuquerque, NM ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cory","family":"Hansen","sequence":"additional","affiliation":[{"name":"TriCore Reference Laboratories , Albuquerque, NM ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1779-5757","authenticated-orcid":false,"given":"Melissa M","family":"Budelier","sequence":"additional","affiliation":[{"name":"TriCore Reference Laboratories , Albuquerque, NM ,","place":["United States"]},{"name":"Department of Pathology, University of New Mexico , Albuquerque, NM ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,1,7]]},"reference":[{"key":"2026050509530233200_jfaf199-B1","doi-asserted-by":"crossref","first-page":"e22587","DOI":"10.1002\/jcla.22587","article-title":"Comparison of whole-blood tacrolimus concentrations measured by different immunoassay 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