{"id":"t3-uptake","name":"T3 Uptake","shortName":"T3 uptake","aliases":["T3 Resin Uptake","T3U","Triiodothyronine Uptake","Thyroid Hormone Binding Ratio","THBR","T3 Uptake, Serum","T3RU","T-Uptake","T Uptake","Triiodothyronine Resin Uptake","Thyroxine Binding Index","T3 Uptake (T3U)"],"abbreviations":["T3U","T3RU","THBR"],"loinc":[{"code":"3050-2","primary":true},{"code":"74794-9","primary":false}],"specimen":"serum-or-plasma","units":[{"ucum":"%","display":"%"}],"referenceRanges":[{"population":"Adults","low":22,"high":35,"unit":"%","unitDisplay":"%","note":"Traditional percent scale. This interval is printed in one published case-report table (the laboratory is not named), and no laboratory directory page could be opened to confirm it. Another published table prints 24 to 39%, so the interval varies by laboratory. Some analyzers report a binding ratio near 1.00 instead (the ATA-commissioned 2023 review says the reference may be assigned 1.00 or 40%, depending on method); those values are not comparable with this percent scale (one hospital's Roche analyzer prints a ratio with a 0.7 to 1.2 interval). Use the interval printed on your own report.","sources":[{"title":"Post-COVID Myoclonus-Ataxia Syndrome: A Case Report of Successful Recovery With Intravenous Immunoglobulin (IVIG) Treatment (Table 3: laboratory thyroid panel with reference ranges)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12702629/","publisher":"Cureus","year":2025},{"title":"A Rare Case of Primary Thyroid Lymphoma (Table 1: laboratory results with reference ranges)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC13274580/","publisher":"Cureus","year":2026},{"title":"Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10517335/","publisher":"Thyroid (American Thyroid Association)","year":2023},{"title":"Measurement of Serum Free Thyroxine Index May Provide Additional Case Detection Compared to Free Thyroxine in the Diagnosis of Central Hypothyroidism","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC4686635/","publisher":"Case Reports in Endocrinology","year":2015}]}],"review":{"status":"ai-draft","label":"AI-drafted. Awaiting verification","lastReviewed":"2026-10-03"},"summary":"Shows how many binding spots on your blood proteins are open for thyroid hormone. It is not a hormone level, and it is used to work out the free thyroxine index.","url":"https://bloodtesttracker.com/markers/t3-uptake","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}