{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T16:23:11Z","timestamp":1783527791720,"version":"3.55.0"},"reference-count":34,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,6]],"date-time":"2026-07-06T00:00:00Z","timestamp":1783296000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diseases"],"abstract":"<jats:p>Background: Vitamin D is a key regulator of skeletal homeostasis, and hypovitaminosis D is highly prevalent among postmenopausal women, who are at increased risk of osteoporosis, sarcopenia, and related complications. Accurate assessment of serum 25-hydroxyvitamin D [25(OH)D] is therefore essential. However, substantial variability exists among analytical methods, particularly between automated chemiluminescent immunoassays (CLIA) and liquid chromatography\u2013tandem mass spectrometry (LC-MS\/MS), the latter considered the reference technique. This study aimed to compare four analytical methods, three CLIA platforms, and LC-MS\/MS for measuring circulating 25(OH)D levels in a cohort of menopausal and postmenopausal women. Methods: A total of 425 serum samples from menopausal and postmenopausal women representing the real-world distribution of vitamin D levels in this population were analyzed using three automated CLIA systems and LC-MS\/MS. Method comparison, agreement, precision through quality control assessment, total error, and sigma were evaluated. Results: The evaluated CLIA platforms (Abbott, Snibe, and Siemens) showed strong correlation with LC-MS\/MS, with r = 0.919, r = 0.978, and r = 0.879. Furthermore, all assays showed excellent precision (CV &lt; 5%), with good-to-acceptable total error (TE) and Sigma-metric performance. Conclusions: In conclusion, these findings demonstrate that while CLIA platforms offer a reliable and precise alternative for routine clinical use, these findings underscore the importance of method selection and result interpretation in the clinical assessment of vitamin D status in postmenopausal women. Furthermore, it highlights the ongoing need to minimize inter-assay variability and ensure consistent vitamin D assessment.<\/jats:p>","DOI":"10.3390\/diseases14070245","type":"journal-article","created":{"date-parts":[[2026,7,6]],"date-time":"2026-07-06T13:43:14Z","timestamp":1783345394000},"page":"245","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Circulating 25-Hydroxy-Vitamin D Levels in Menopausal and Postmenopausal Women in Italy: A Comparison of Four Analytical Methods"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6336-814X","authenticated-orcid":false,"given":"Flaminia","family":"Tomassetti","sequence":"first","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Biomedicine and Prevention, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-6028-9739","authenticated-orcid":false,"given":"Martina","family":"Pelagalli","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, Tor Vergata University Hospital, viale Oxford, 81, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-5293-6275","authenticated-orcid":false,"given":"Federico","family":"Cortese","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, University of Rome Tor Vergata, via del Politecnico, 1, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-5820-4768","authenticated-orcid":false,"given":"Alfredo","family":"Giovannelli","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Industrial Engineering, University of Rome Tor Vergata, via del Politecnico, 1, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-8470-5584","authenticated-orcid":false,"given":"Enrico Maria","family":"Carloni","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Electronic Engineering, University of Rome Tor Vergata, via del Politecnico, 1, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Morello","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Laboratory Medicine, Tor Vergata University Hospital, viale Oxford, 81, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1415-9808","authenticated-orcid":false,"given":"Eleonora","family":"Nicolai","sequence":"additional","affiliation":[{"name":"Departmental Faculty of Medicine, UniCamillus-Saint Camillus International University of Health and Medical Sciences, via di Sant\u2019Alessandro, 8, 00131 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7442-2252","authenticated-orcid":false,"given":"Alessandro","family":"Terrinoni","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Laboratory Medicine, Tor Vergata University Hospital, viale Oxford, 81, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3463-0268","authenticated-orcid":false,"given":"Massimo","family":"Pieri","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Laboratory Medicine, Tor Vergata University Hospital, viale Oxford, 81, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sergio","family":"Bernardini","sequence":"additional","affiliation":[{"name":"Department of Experimental Medicine, University of Rome Tor Vergata, via Montpellier, 1, 00133 Rome, Italy"},{"name":"Department of Laboratory Medicine, Tor Vergata University Hospital, viale Oxford, 81, 00133 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Zhang, J.-L., Poon, C.C.-W., Wong, M.-S., Li, W.-X., Guo, Y.-X., and Zhang, Y. 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