{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T05:37:03Z","timestamp":1783489023834,"version":"3.55.0"},"reference-count":35,"publisher":"SAGE Publications","issue":"5","license":[{"start":{"date-parts":[[2024,5,1]],"date-time":"2024-05-01T00:00:00Z","timestamp":1714521600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Thyroid\u00ae"],"published-print":{"date-parts":[[2024,5]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>Initial evaluation of the hypothalamus\u2013pituitary\u2013thyroid axis is done by measuring serum free thyroxine (fT4) and thyrotropin concentrations. For correct interpretation of these measurements, reliable age-specific reference intervals (RIs) are fundamental. Since neonatal fT4 RIs conforming to the Clinical and Laboratory Standards Institute guidelines are not available for all assays, we set out to create literature-based uniform age-specific neonatal fT4 RIs that may be used for every assay.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>For meta-analysis of individual participant fT4 concentrations, we systematically searched MEDLINE and Embase (search date December 6, 2023; PROSPERO registration CRD42016041871). We searched for studies reporting fT4 concentrations in healthy term newborns aged 2\u201327 days, born to mothers without thyroid disease in iodine-sufficient regions. Authors were invited to supply data. Due to standardization differences between assays, data could not be combined for meta-analysis directly, and we attempted to normalize the data using two distinct methods.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>\n                      We obtained 4206 fT4 concentrations from 20 studies that used 13 different assays from 6 manufacturers. First, we set out to normalize fT4 data using the mean and standard deviation of (assay-specific) adult RIs. fT4 concentrations were transformed into Z-scores, assuming a normal distribution. Using a linear mixed-effects model (LMM), we still found a significant difference between fT4 concentration across studies (\n                      <jats:italic toggle=\"yes\">p<\/jats:italic>\n                      \u2009&lt;\u20090.001), after this normalization. As a second approach, we normalized the fT4 concentrations using data from a method\/assay comparison study. We used the relationship between the Cobas assay and the other assays as a reference point to convert all values to Cobas values. However, this method also failed to produce consistent results, with significant differences between the normalized data (LMM\n                      <jats:italic toggle=\"yes\">p<\/jats:italic>\n                      \u2009&lt;\u20090.001).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions:<\/jats:title>\n                    <jats:p>We conclude that our attempts at normalizing fT4 assay results were unsuccessful. Confounders related to our unsuccessful analysis may be assay related and\/or biological. These findings have significant implications for patient care, since relying on RIs from literature may result in erroneous interpretation of results. Therefore, we strongly recommend to establish local RIs for accurate interpretation of serum fT4 concentrations in neonates.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1089\/thy.2023.0562","type":"journal-article","created":{"date-parts":[[2024,3,5]],"date-time":"2024-03-05T09:10:55Z","timestamp":1709629855000},"page":"559-565","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":5,"title":["Analysis of Serum Free Thyroxine Concentrations in Healthy Term Neonates Underlines Need for Local and Laboratory-Specific Reference Interval: A Systematic Review and Meta-Analysis of Individual Participant Data"],"prefix":"10.1177","volume":"34","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1174-7340","authenticated-orcid":false,"given":"Peter","family":"Lauffer","sequence":"first","affiliation":[{"name":"Department of Pediatric Endocrinology, Emma Children's Hospital, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Charlotte A.","family":"Heinen","sequence":"additional","affiliation":[{"name":"Department of Pediatric Endocrinology, Emma Children's Hospital, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annika W.M.","family":"Goorsenberg","sequence":"additional","affiliation":[{"name":"Department of Pediatric Endocrinology, Emma Children's Hospital, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arjan","family":"Malekzadeh","sequence":"additional","affiliation":[{"name":"Medical Library, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Henneman","sequence":"additional","affiliation":[{"name":"Department of Human Genetics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annemieke C.","family":"Heijboer","sequence":"additional","affiliation":[{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Endocrine Laboratory, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Endocrine Laboratory, Amsterdam University Medical Centers, VU University, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nitash","family":"Zwaveling-Soonawala","sequence":"additional","affiliation":[{"name":"Department of Pediatric Endocrinology, Emma Children's Hospital, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anita","family":"Boelen","sequence":"additional","affiliation":[{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Endocrine Laboratory, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9677-7441","authenticated-orcid":false,"given":"A.S. Paul","family":"van Trotsenburg","sequence":"additional","affiliation":[{"name":"Department of Pediatric Endocrinology, Emma Children's Hospital, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."},{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2024,5,24]]},"reference":[{"key":"e_1_3_6_2_2","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2020.0333"},{"key":"e_1_3_6_3_2","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2000.10.229"},{"key":"e_1_3_6_4_2","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2019.0779"},{"key":"e_1_3_6_5_2","doi-asserted-by":"publisher","DOI":"10.1373\/clinchem.2013.204222"},{"key":"e_1_3_6_6_2","unstructured":"Horowitz GL. Defining Establishing and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline\u2014Third Edition. Clinical and Laboratory Standards Institute; 2008."},{"key":"e_1_3_6_7_2","doi-asserted-by":"publisher","DOI":"10.1373\/clinchem.2017.274407"},{"key":"e_1_3_6_8_2","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.b2535"},{"key":"e_1_3_6_9_2","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2015.3656"},{"key":"e_1_3_6_10_2","volume-title":"Department of Nutrition for Health and Development, World Health Organization","author":"De Benoist B","year":"2004","unstructured":"De Benoist B, , Andersson M, , Egli IM, et al. Iodine Status Worldwide: WHO Global Database on Iodine Deficiency. Department of Nutrition for Health and Development, World Health Organization: Geneva; 2004."},{"key":"e_1_3_6_11_2","unstructured":"Iodine Global Network. Global iodine nutrition scorecard 2015. Available from: http:\/\/ign.org\/cm_data\/Scorecard_2015_August_26.pdf [Last accessed: January5 2024]."},{"key":"e_1_3_6_12_2","unstructured":"Wells G Shea B O'Connell D et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Available from: www.ohri.ca\/programs\/clinical_epidemiology\/nosgen.pdf [Last accessed: January5 2024]."},{"key":"e_1_3_6_13_2","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2020-1696"},{"key":"e_1_3_6_14_2","doi-asserted-by":"publisher","DOI":"10.1530\/etj-22-0145"},{"key":"e_1_3_6_15_2","doi-asserted-by":"publisher","DOI":"10.1159\/000354688"},{"key":"e_1_3_6_16_2","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2019-0707"},{"key":"e_1_3_6_17_2","doi-asserted-by":"publisher","DOI":"10.11613\/BM.2021.030702"},{"key":"e_1_3_6_18_2","doi-asserted-by":"publisher","DOI":"10.1515\/jpem.2010.125"},{"key":"e_1_3_6_19_2","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2017-0349"},{"key":"e_1_3_6_20_2","doi-asserted-by":"publisher","DOI":"10.1515\/CCLM.2002.182"},{"key":"e_1_3_6_21_2","doi-asserted-by":"publisher","DOI":"10.1186\/1472-6823-8-15"},{"key":"e_1_3_6_22_2","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2015-0558"},{"key":"e_1_3_6_23_2","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2012-1759"},{"key":"e_1_3_6_24_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12902-016-0107-9"},{"key":"e_1_3_6_25_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12902-023-01367-6"},{"key":"e_1_3_6_26_2","doi-asserted-by":"publisher","DOI":"10.1155\/2013\/987843"},{"issue":"2","key":"e_1_3_6_27_2","first-page":"248","article-title":"[Reference intervals for total triiodothyronine (TT3), free thyroxine (FT4), and thyrotropin (TSH) by chemiluminescence immunoassay in children younger than six years old from northeastern Mexico]","volume":"150","author":"Romero-Villarreal JB","year":"2014","unstructured":"Romero-Villarreal JB, , Palacios-Saucedo GC, , Ocana-Hernandez LA, et al. [Reference intervals for total triiodothyronine (TT3), free thyroxine (FT4), and thyrotropin (TSH) by chemiluminescence immunoassay in children younger than six years old from northeastern Mexico]. Gac Med Mex, 2014; 150(Suppl 2):248\u2013254.","journal-title":"Gac Med Mex"},{"key":"e_1_3_6_28_2","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.84.2.5439"},{"key":"e_1_3_6_29_2","doi-asserted-by":"publisher","DOI":"10.1080\/14767050701398314"},{"key":"e_1_3_6_30_2","doi-asserted-by":"publisher","DOI":"10.1159\/000448050"},{"key":"e_1_3_6_31_2","doi-asserted-by":"publisher","DOI":"10.1055\/s-0031-1275326"},{"key":"e_1_3_6_32_2","doi-asserted-by":"publisher","DOI":"10.1515\/jpem-2020-0148"},{"key":"e_1_3_6_33_2","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2017.0262"},{"key":"e_1_3_6_34_2","doi-asserted-by":"publisher","DOI":"10.1093\/clinchem\/hvac142"},{"key":"e_1_3_6_35_2","doi-asserted-by":"publisher","DOI":"10.3389\/fendo.2021.686317"},{"key":"e_1_3_6_36_2","doi-asserted-by":"publisher","DOI":"10.1530\/etj-23-0041"}],"container-title":["Thyroid\u00ae"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/full-xml\/10.1089\/thy.2023.0562","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1089\/thy.2023.0562","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1089\/thy.2023.0562","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T22:11:20Z","timestamp":1777587080000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1089\/thy.2023.0562"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,5]]},"references-count":35,"journal-issue":{"issue":"5","published-print":{"date-parts":[[2024,5]]}},"alternative-id":["10.1089\/thy.2023.0562"],"URL":"https:\/\/doi.org\/10.1089\/thy.2023.0562","relation":{},"ISSN":["1050-7256","1557-9077"],"issn-type":[{"value":"1050-7256","type":"print"},{"value":"1557-9077","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,5]]}}}