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Logo of jcinvestThe Journal of Clinical Investigation
J Clin Invest. 1974 February; 53(2): 416–422.
PMCID: PMC301484

A multiple ligand-binding radioimmunoassay of diiodotyrosine.


A radioimmunoassay has been developed for the measurement of 3,5-diiodo-L-tyrosine (DIT) in serum. DIT was coupled to porcine thyroglobulin (PTg) with a molar ratio of 205:1. Rabbits were immunized with 1 mg of immunogen emulsified in complete Freund's adjuvant. Sera were screened for their ability to bind trace amounts of [125I]DIT. A serum that bound 40% of the tracer at a final dilution of 1:1,750 was used in the assay. Assay specificity was improved by the use of thyroxine (T4)-binding globulin as a second ligand-binding protein to decrease T4 and triiodothyronine (T3) cross-reactivity with the antibody. Double antibody and polyethylene glycol radioimmunoassays were compared. DIT present in the second antiserum shifted the double antibody assay standard curve and altered estimates of assay specificity and assay sensitivity. By using the polyethylene glycol system and butanol:ethanol extracts of serum, DIT was measured in human serum. In 35 apparently healthy young adult controls DIT levels averaged 156 ng/100 ml. Random DIT levels averaged 158 ng/100 ml in 11 untreated hyperthyroid patients and 84 ng/100 ml in 15 untreated primary hypothyroid patients. No diurnal pattern in DIT levels could be demonstrated. Thyroid-stimulating hormone administration led to a variable but small rise in DIT levels, but short term T3 suppression was not associated with a measurable fall in DIT concentrations. Paired serum samples from the carotid artery and thyroid vein of 10 euthyroid goiter patients and one patient with a toxic solitary adenoma all showed a positive transthyroidal gradient indicating the thyroidal release of DIT in each patient. Measurable DIT levels of 45, 47, 68, and 80 ng/100 ml, respectively, were found in four fasting athyrotic patients indicating that the thyroid is not the only source of serum DIT.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Fisher DA, Oddie TH, Thompson CS. Thyroidal thyronine and non-thyronine iodine secretion in euthyroid subjects. J Clin Endocrinol Metab. 1971 Oct;33(4):647–652. [PubMed]
  • Weinert H, Masui H, Radichevich I, Werner SC. Materials indistinguishable from iodotyrosines in normal human serum and human serum albumin. J Clin Invest. 1967 Jul;46(7):1264–1274. [PMC free article] [PubMed]
  • Bismuth J, Castay M, Lissitzky S. Sephadex filtration of serum iodocompounds and protein-binding of iodotyrosines. Clin Chim Acta. 1971 Dec;35(2):285–298. [PubMed]
  • Gharib H, Mayberry WE, Ryan RJ. Radioimmunoassay for triiodothyronine: A preliminary report. J Clin Endocrinol Metab. 1970 Dec;31(6):709–712. [PubMed]
  • Chopra IJ, Solomon DH, Beall GN. Radioimmunoassay for measurement of triiodothyronine in human serum. J Clin Invest. 1971 Oct;50(10):2033–2041. [PMC free article] [PubMed]
  • Mitsuma T, Nihei N, Gershengorn MC, Hollander CS. Serum triiodothyronine: measurements in human serum by radioimmunoassay with corroboration by gas-liquid chromatography. J Clin Invest. 1971 Dec;50(12):2679–2688. [PMC free article] [PubMed]
  • Lieblich J, Utiger RD. Triiodothyronine radioimmunoassay. J Clin Invest. 1972 Jan;51(1):157–166. [PMC free article] [PubMed]
  • Larsen PR. Direct immunoassay of triiodothyronine in human serum. J Clin Invest. 1972 Aug;51(8):1939–1949. [PMC free article] [PubMed]
  • Chopra IJ, Solomon DH, Ho RS. A radioimmunoassay of thyroxine. J Clin Endocrinol Metab. 1971 Nov;33(5):865–868. [PubMed]
  • Chopra IJ, Nelson JC, Solomon DH, Beall GN. Production of antibodies specifically binding triiodothyronine and thyroxine. J Clin Endocrinol Metab. 1971 Mar;32(3):299–308. [PubMed]
  • Desbuquois B, Aurbach GD. Use of polyethylene glycol to separate free and antibody-bound peptide hormones in radioimmunoassays. J Clin Endocrinol Metab. 1971 Nov;33(5):732–738. [PubMed]
  • Rodbard D, Bridson W, Rayford PL. Rapid calculation of radioimmunoassay results. J Lab Clin Med. 1969 Nov;74(5):770–781. [PubMed]
  • Haibach H. Comparison of the intrathyroidal fate of iodotyrosine-derived and newly entering iodide in the rat. Endocrinology. 1971 Jul;89(1):184–190. [PubMed]

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