{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,27]],"date-time":"2025-09-27T00:13:26Z","timestamp":1758932006140,"version":"3.44.0"},"reference-count":12,"publisher":"BMJ","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Clin Pathol"],"published-print":{"date-parts":[[1972,3]]},"abstract":"<jats:p>The T<jats:sub>4<\/jats:sub>-free thyroxine index was used as the thyroid function test of first choice in a district general hospital for one year. Ninety-two patients were assessed both initially and at follow up by a single physician. The index agreed with clinical assessment in 69 out of 74 patients in whom diagnosis was unequivocal. There was initial doubt about thyroid status in 14 patients; after re-assessment the index agreed with status in seven cases, in three cases there is still some uncertainty, whilst the index was at variance with clinical status in four patients. Some possible causes of discrepancy between clinical thyroid status and the index are a low index in euthyroid patients due to a fall in serum thyroxine-binding prealbumin (`sick euthyroid'), a raised index in euthyroid patients due to latent thyroid heart disease, and a normal index in thyrotoxicosis due to preferential secretion of triiodothyronine.<\/jats:p>","DOI":"10.1136\/jcp.25.3.259","type":"journal-article","created":{"date-parts":[[2007,6,9]],"date-time":"2007-06-09T00:50:46Z","timestamp":1181350246000},"page":"259-262","source":"Crossref","is-referenced-by-count":7,"title":["The T<sub>4<\/sub>-free thyroxine index as a test of thyroid function of first choice"],"prefix":"10.1136","volume":"25","author":[{"given":"P. J. N.","family":"Howorth","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richard L.","family":"Ward","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[1972,3,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1172\/JCI106304","article-title":"Conversionb of thyroxine (T4) to triiodothyronine (T,) in athyreotic human subjects","volume":"49","author":"Braverman, L.E.; Ingbar, S.H.; Sterling, K.","year":"1970","unstructured":"Braverman, L. E., Ingbar, S. H., and Sterling, K. (1970). Conversionb of thyroxine (T4) to triiodothyronine (T,) in athyreotic human subjects. J. clin. Invest., 49, 855-864.","journal-title":"J. clin. Invest"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1210\/jcem-25-1-39","article-title":"Assessment of thyroid function by the combined use of the serum protein-bound iodine and resin, uptake of 1'I-triiodothyronine","volume":"25","author":"Clark, F.; Horn, D.B.","year":"1965","unstructured":"Clark, F., and Horn, D. B. (1965). Assessment of thyroid function by the combined use of the serum protein-bound iodine and resin, uptake of 1'I-triiodothyronine. J. clin. Endocr., 25, 39-45.","journal-title":"J. clin. Endocr"},{"key":"ref_3","first-page":"12","article-title":"Thyroid status in pregnancy and in women taking oral contraceptives","volume":"1","author":"Goolden, A.W.G.; Gartside, J.M.; Sanderson, C.","year":"1967","unstructured":"Goolden, A. W. G., Gartside, J. M., and Sanderson, C. (1967). Thyroid status in pregnancy and in women taking oral contraceptives. 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Biochem"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1016\/S0140-6736(69)91240-9","article-title":"Clinical application of serum-total-thyroxine estimation, resin uptake, and freethyroxine index","volume":"1","author":"Howorth, P.J.N.; Maclagan, N.F.","year":"1969","unstructured":"Howorth, P. J. N., and Maclagan, N. F. (1969). Clinical application of serum-total-thyroxine estimation, resin uptake, and freethyroxine index. Lancet, 1, 224-228.","journal-title":"Lancet"},{"key":"ref_7","first-page":"37","article-title":"Thyroid function studies using resin uptake ofradioactive thyronines from serum and total thyroxine assay: the free thyroxine index","author":"Maclagan, N.F.; Howorth, P.J.N.","year":"1969","unstructured":"Maclagan, N. F., and Howorth, P. J. N. (1969). Thyroid function studies using resin uptake ofradioactive thyronines from serum and total thyroxine assay: the free thyroxine index. Clin. Sci., 37,45-60.","journal-title":"Clin. Sci"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"601","DOI":"10.1113\/jphysiol.1960.sp006511","article-title":"Paper electrophoresis of thyroxine in tris-maleate buffer","volume":"152","author":"Myant, N.B.; Osorio, C.","year":"1960","unstructured":"Myant, N. B., and Osorio, C. (1960). Paper electrophoresis of thyroxine in tris-maleate buffer. J. Physiol. (Lond.), 152, 601-612.","journal-title":"J. Physiol. (Lond.)"},{"key":"ref_9","first-page":"23","article-title":"The assessment of free thyroxine in plasma","author":"Osorio, C.; Jackson, D.J.; Gartside, J.M.; Goolden, A.W.G.","year":"1962","unstructured":"Osorio, C., Jackson, D. J., Gartside, J. M., and Goolden, A. W. G. (1962). The assessment of free thyroxine in plasma. Clin. Sci., 23,525-530.","journal-title":"Clin. Sci"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"597","DOI":"10.1016\/0009-8981(61)90102-4","article-title":"A systematic study of factors affecting the binding of thyroxine and related substances to serum proteins","volume":"6","author":"Tata, J.R.; Widnell, C.C.; Gratzer, W.B.","year":"1961","unstructured":"Tata, J. R., Widnell, C. C., and Gratzer, W. B. (1961). A systematic study of factors affecting the binding of thyroxine and related substances to serum proteins. Clin. chim. Acta, 6, 597-612.","journal-title":"Clin. chim. Acta"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1136\/bmj.2.5704.270","article-title":"Combined thyroxine and triiodothyronine for thyroid replacement therapy","volume":"2","author":"Taylor, S.; Kapur, M.; Adie, R.","year":"1970","unstructured":"Taylor, S., Kapur, M., and Adie, R. (1970). Combined thyroxine and triiodothyronine for thyroid replacement therapy. Brit. med. J., 2, 270-271.","journal-title":"Brit. med. J"},{"key":"ref_12","first-page":"486","article-title":"A new method for the direct determination of serum cholesterol","volume":"41","author":"Zlatkis, A.; Zak, B.; Boyle, A.J.","year":"1953","unstructured":"Zlatkis, A., Zak, B., and Boyle, A. J. (1953). A new method for the direct determination of serum cholesterol. J. Lab. clin. Med., 41, 486-492.","journal-title":"J. Lab. clin. 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