{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:29:05Z","timestamp":1760059745686,"version":"build-2065373602"},"reference-count":20,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2025,7,7]],"date-time":"2025-07-07T00:00:00Z","timestamp":1751846400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background: The least significant change (LSC) method should be introduced and considered a proper method to define the smallest clinically important difference between two consecutive measurements. Methods: The LSC was calculated based on 150 patients, with a total 25-hydroxyvitamin D [25(OH)D] IDS-iSYS assay performed in triplicate. The LSC was determined by multiplying the calculated root mean square precision error by a factor of 2.77. The study group was additionally divided into subgroups according to gender, age, serum 25(OH)D concentration, and date of assays. Results: The LSC was 4.0 ng\/mL (13.2%) for the entire group (n = 150; 450 assays) and was not dependent on gender, age of patients, or the date of assays (p &gt; 0.05). The LSC value depended only on the 25(OH)D concentration value. In the subgroup with vitamin D deficiency (&lt;20 ng\/mL), the obtained LSC value was 2.2 ng\/mL (14.7%), which was lower compared to all other groups (p &lt; 0.05 for insufficiency, and p &lt; 0.0001 for the optimal concentration value). In the subgroup with 25(OH)D concentrations &gt;50 ng\/mL (n = 4; 12 assays), the calculated LSC was 11.8 ng\/mL (16.9%) and differed statistically only from the subgroup with vitamin D deficiency (p &lt; 0.005). Conclusions: An absolute LSC of 4.0 ng\/mL was calculated for the IDS-iSYS assay used in our study and should be considered when two (or more) assay results of 25(OH)D performed for a single patient are compared.<\/jats:p>","DOI":"10.3390\/nu17132246","type":"journal-article","created":{"date-parts":[[2025,7,7]],"date-time":"2025-07-07T08:58:23Z","timestamp":1751878703000},"page":"2246","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Least Significant Change (LSC) for Serum Concentrations of 25-Hydroxyvitamin D"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8475-7112","authenticated-orcid":false,"given":"Pawel","family":"Pludowski","sequence":"first","affiliation":[{"name":"Department of Clinical Biochemistry, The Children\u2019s Memorial Health Institute, 04-730 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marek","family":"W\u00f3jcik","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry, The Children\u2019s Memorial Health Institute, 04-730 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6758-371X","authenticated-orcid":false,"given":"Maciej","family":"Jaworski","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry, The Children\u2019s Memorial Health Institute, 04-730 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6997-6197","authenticated-orcid":false,"given":"Agnieszka","family":"Ochoci\u0144ska","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry, The Children\u2019s Memorial Health Institute, 04-730 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1439-3285","authenticated-orcid":false,"given":"William","family":"Grant","sequence":"additional","affiliation":[{"name":"Sunlight, Nutrition, and Health Research Center, 1745 Pacific Ave., Ste. 504, San Francisco, CA 94109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6023-9062","authenticated-orcid":false,"given":"Michael","family":"Holick","sequence":"additional","affiliation":[{"name":"Section Endocrinology, Diabetes, Nutrition and Weight Management, Department of Medicine, School of Medicine, Boston University, Boston, MA 02118, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,7]]},"reference":[{"key":"ref_1","first-page":"47","article-title":"The distribution of the largest of a set of estimated variances as a fraction of their total","volume":"11","author":"Cochran","year":"1941","journal-title":"Ann. 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