{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T22:30:21Z","timestamp":1784673021542,"version":"3.55.0"},"reference-count":35,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2023,9,18]],"date-time":"2023-09-18T00:00:00Z","timestamp":1694995200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["pericles.pericles-gcp.literatumonline.com"],"crossmark-restriction":true},"short-container-title":["Clinical Endocrinology"],"published-print":{"date-parts":[[2023,12]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>Interpreting thyroid function tests can be challenging due to inherent variation, and the need for tests rises with age. While age\u2010related changes in thyrotropin (TSH) levels are known, the biological variation in older adults remains unclear.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>We recruited nineteen 65\u201399\u2010year\u2010old (older adults) without thyroid disease for monthly blood sampling for 1 year.<\/jats:p><\/jats:sec><jats:sec><jats:title>Patients and Measurements<\/jats:title><jats:p>Serum was stored at \u221220C\u00b0, and TSH, total thyroxine (TT4) and total triiodothyronine (TT3) were analysed in random order in a single batch for each participant. Results were compared to test results from 15 euthyroid men aged 24\u201353 years (younger adults) collected previously using a similar methodology.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Interindividual coefficients of variation in older\/younger adults were 46.7%\/44.0% for TSH, 12.7%\/19.5% for TT4 and 14.6%\/22.4% for TT3. Intraindividual coefficients of variation (CV<jats:sub>I<\/jats:sub>) were 19.0%\/25.4% for TSH, 5.5%\/10.8% for TT4 and 6.9%\/13.2% for TT3. The index of individuality was below 0.6 for all hormones in all age groups. The number of samples required to determine the homoeostatic set\u2010point at 10% precision in older adults was 14\u201321 for TSH and 2 for TT4 and TT3. TT4 in older adults was the only parameter in any group with comparable CV<jats:sub>I<\/jats:sub> between individuals (<jats:italic>p<\/jats:italic>\u2009=\u2009.22).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>CV<jats:sub>I<\/jats:sub> for TT4 and TT3 was halved in older compared to younger adults with two tests of TT4 needed to describe the individual set\u2010point. Similar CV<jats:sub>I<\/jats:sub> between older adults caused TT4 to provide a reliable estimate of thyroid function, and the added value of measuring thyroxine could improve clinical practice.<\/jats:p><\/jats:sec>","DOI":"10.1111\/cen.14973","type":"journal-article","created":{"date-parts":[[2023,9,19]],"date-time":"2023-09-19T04:49:31Z","timestamp":1695098971000},"page":"598-605","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Biological variation in thyroid function tests in older adults and clinical implications"],"prefix":"10.1111","volume":"99","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8398-5420","authenticated-orcid":false,"given":"Johannes","family":"Riis","sequence":"first","affiliation":[{"name":"Department of Clinical Medicine Aalborg University Aalborg Denmark"},{"name":"Department of Geriatric Medicine Aalborg University Hospital Aalborg Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Louise","family":"Westergaard","sequence":"additional","affiliation":[{"name":"Department of Clinical Medicine Aalborg University Aalborg Denmark"},{"name":"Department of Geriatric Medicine Aalborg University Hospital Aalborg Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6026-5834","authenticated-orcid":false,"given":"Jesper","family":"Karmisholt","sequence":"additional","affiliation":[{"name":"Department of Clinical Medicine Aalborg University Aalborg Denmark"},{"name":"Department of Endocrinology Aalborg University Hospital Aalborg Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6336-1936","authenticated-orcid":false,"given":"Stine Linding","family":"Andersen","sequence":"additional","affiliation":[{"name":"Department of Clinical Medicine Aalborg University Aalborg Denmark"},{"name":"Department of Clinical Biochemistry Aalborg University Hospital Aalborg Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stig","family":"Andersen","sequence":"additional","affiliation":[{"name":"Department of Clinical Medicine Aalborg University Aalborg Denmark"},{"name":"Department of Geriatric Medicine Aalborg University Hospital Aalborg Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2023,9,18]]},"reference":[{"key":"e_1_2_11_2_1","doi-asserted-by":"publisher","DOI":"10.1001\/archinte.160.4.526"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.87.2.8182"},{"key":"e_1_2_11_4_1","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.83.3.4624"},{"key":"e_1_2_11_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.maturitas.2009.08.007"},{"key":"e_1_2_11_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.beem.2009.08.013"},{"key":"e_1_2_11_7_1","doi-asserted-by":"publisher","DOI":"10.1530\/EJE-17-0321"},{"key":"e_1_2_11_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.amjmed.2016.06.013"},{"key":"e_1_2_11_9_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1603825"},{"key":"e_1_2_11_10_1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2019.17274"},{"key":"e_1_2_11_11_1","doi-asserted-by":"publisher","DOI":"10.1530\/EJE-10-1021"},{"key":"e_1_2_11_12_1","doi-asserted-by":"publisher","DOI":"10.1530\/EJE-07-0407"},{"key":"e_1_2_11_13_1","doi-asserted-by":"publisher","DOI":"10.1093\/clinchem\/20.12.1535"},{"key":"e_1_2_11_14_1","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.87.3.8165"},{"key":"e_1_2_11_15_1","doi-asserted-by":"publisher","DOI":"10.1177\/000456328502200407"},{"key":"e_1_2_11_16_1","doi-asserted-by":"publisher","DOI":"10.1093\/clinchem\/32.6.962"},{"key":"e_1_2_11_17_1","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2017.0211"},{"key":"e_1_2_11_18_1","doi-asserted-by":"publisher","DOI":"10.1038\/nrendo.2013.38"},{"key":"e_1_2_11_19_1","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2006.0191"},{"key":"e_1_2_11_20_1","doi-asserted-by":"publisher","DOI":"10.1097\/MED.0000000000000758"},{"key":"e_1_2_11_21_1","doi-asserted-by":"publisher","DOI":"10.1001\/jamainternmed.2021.2686"},{"key":"e_1_2_11_22_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12877-020-01850-y"},{"key":"e_1_2_11_23_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2265.2003.01633.x"},{"key":"e_1_2_11_24_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2265.2001.01347.x"},{"key":"e_1_2_11_25_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0007114507842292"},{"key":"e_1_2_11_26_1","doi-asserted-by":"publisher","DOI":"10.3109\/10408368909106595"},{"key":"e_1_2_11_27_1","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2020-1885"},{"key":"e_1_2_11_28_1","doi-asserted-by":"publisher","DOI":"10.1089\/thy.2018.0539"},{"key":"e_1_2_11_29_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2265.1997.1881002.x"},{"key":"e_1_2_11_30_1","doi-asserted-by":"publisher","DOI":"10.1515\/cclm-2022-1130"},{"key":"e_1_2_11_31_1","doi-asserted-by":"publisher","DOI":"10.1210\/edrv.23.1.0455"},{"key":"e_1_2_11_32_1","doi-asserted-by":"publisher","DOI":"10.1210\/er.2018-00275"},{"key":"e_1_2_11_33_1","doi-asserted-by":"publisher","DOI":"10.1258\/acb.2007.007103"},{"key":"e_1_2_11_34_1","doi-asserted-by":"publisher","DOI":"10.1007\/s40618-020-01482-4"},{"key":"e_1_2_11_35_1","doi-asserted-by":"publisher","DOI":"10.1530\/EJE-11-0575"},{"key":"e_1_2_11_36_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.clinbiochem.2014.06.007"}],"container-title":["Clinical Endocrinology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/cen.14973","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,29]],"date-time":"2023-11-29T11:28:28Z","timestamp":1701257308000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/cen.14973"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,9,18]]},"references-count":35,"journal-issue":{"issue":"6","published-print":{"date-parts":[[2023,12]]}},"alternative-id":["10.1111\/cen.14973"],"URL":"https:\/\/doi.org\/10.1111\/cen.14973","archive":["Portico"],"relation":{},"ISSN":["0300-0664","1365-2265"],"issn-type":[{"value":"0300-0664","type":"print"},{"value":"1365-2265","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,9,18]]},"assertion":[{"value":"2023-06-04","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2023-09-07","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2023-09-18","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}