{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T05:00:08Z","timestamp":1791090008782,"version":"4.1.0"},"reference-count":11,"publisher":"BMJ","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["BMJ Case Reports"],"published-print":{"date-parts":[[2009]]},"abstract":"<jats:p>Macro-hormones and macro-enzymes are high molecular weight conjugates of hormones or enzymes, respectively, often with immunoglobulins. These are referred to as macromolecular complexes, and may cause artefactually elevated biochemical tests results. Macro enzymes of the most commonly measured serum enzymes have been identified and are recognised as a source of elevated measurements that may cause diagnostic confusion; macro-creatine kinase and macro-amylase are the two better known macro-enzymes in clinical practice. Literature on macro-hormones is largely restricted to macro-prolactin. We present a case of a clinically euthyroid patient, who had persistently elevated thyroid stimulating hormone (TSH) but free thyroxine within the reference limits. She underwent repeated thyroid investigations and thyroid hormone interference studies, until macro-TSH was identified as the most likely cause of unexplained elevated TSH. Following the identification and characterisation of this biochemical abnormality, she is no longer subject to repeated blood tests for assessment of thyroid function; the patient currently remains clinically euthyroid.<\/jats:p>","DOI":"10.1136\/bcr.01.2009.1474","type":"journal-article","created":{"date-parts":[[2009,4,14]],"date-time":"2009-04-14T09:38:20Z","timestamp":1239701900000},"page":"bcr0120091474","source":"Crossref","is-referenced-by-count":15,"title":["Unexplained high thyroid stimulating hormone: a \u201cBIG\u201d problem"],"prefix":"10.1136","volume":"2009","author":[{"given":"Heidi","family":"Mendoza","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alan","family":"Connacher","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rajeev","family":"Srivastava","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2009,4,14]]},"reference":[{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.1","doi-asserted-by":"crossref","first-page":"2261","DOI":"10.1093\/clinchem\/35.12.2261","article-title":"Macroenzymes: biochemical characterization, clinical significance, and laboratory detection","volume":"35","author":"Remaley","year":"1989","journal-title":"Clin Chem"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.2","first-page":"105","article-title":"Interferences in immunoassay","volume":"25","author":"Tate","year":"2004","journal-title":"Clin Biochem Rev"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.3","doi-asserted-by":"publisher","DOI":"10.1515\/CCLM.2007.064"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.4","doi-asserted-by":"publisher","DOI":"10.1001\/jama.291.2.228"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.5","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM200107263450406"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.6","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1111\/j.1365-2265.1987.tb00788.x","article-title":"Anti-TSH antibody with high specificity to human TSH in sera from a patient with Graves\u2019 disease: its isolation from, and interaction with, TSH receptor antibodies","volume":"26","author":"Akamizu","year":"1987","journal-title":"Clin Endocrinol"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.7","doi-asserted-by":"crossref","first-page":"1609","DOI":"10.1056\/NEJM198706183162519","article-title":"High-molecular-weight serum thyrotropin revisited","volume":"316","author":"Bifulco","year":"1987","journal-title":"N Engl J Med"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.8","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.286.6365.592"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.9","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1056\/NEJM198101293040506","article-title":"Increased high-molecular-weight thyrotropin with impaired biologic activity in a euthyroid man","volume":"304","author":"Spitz","year":"1981","journal-title":"N Engl J Med"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.10","doi-asserted-by":"publisher","DOI":"10.1373\/clinchem.2006.071050"},{"key":"2025042507442730000_2009.apr07_2.bcr0120091474.11","doi-asserted-by":"publisher","DOI":"10.1373\/clinchem.2006.070185"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr.01.2009.1474","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,4,25]],"date-time":"2025-04-25T14:44:35Z","timestamp":1745592275000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr.01.2009.1474"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009]]},"references-count":11,"alternative-id":["10.1136\/bcr.01.2009.1474"],"URL":"https:\/\/doi.org\/10.1136\/bcr.01.2009.1474","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009]]}}}