monoiodotyrosine and Graves-Disease

Conventional diagnostic methods are limited in their ability to differentiate destructive thyroiditis from Graves' disease. We hypothesised that serum diiodotyrosine (DIT) and monoiodotyrosine (MIT) levels could be biomarkers for differentiating destructive thyroiditis from Graves' disease.. Patients with destructive thyroiditis (n = 13) and Graves' disease (n = 22) were enrolled in this cross-sectional study.. We assayed the serum DIT and MIT levels using liquid chromatography-tandem mass spectrometry. A receiver operating characteristic (ROC) curve analysis was used to determine the sensitivity and specificity of the serum DIT and MIT levels as biomarkers for differentiating destructive thyroiditis from Graves' disease.. The serum DIT and MIT levels were significantly higher in patients with destructive thyroiditis than in those with Graves' disease. The ROC curve analysis showed that the serum DIT levels (≥359.9 pg/mL) differentiated destructive thyroiditis from Graves' disease, significantly, with 100.0% sensitivity and 95.5% specificity (P < 0.001). The diagnostic accuracy of the serum MIT levels (≥119.4 pg/mL) was not as high as that of the serum DIT levels (sensitivity, 84.6%; specificity, 77.3%; P = 0.001).. The serum DIT levels may serve as a novel diagnostic biomarker for differentiating destructive thyroiditis from Graves' disease.

Topics: Adult; Aged; Biomarkers; Cross-Sectional Studies; Diagnosis, Differential; Diiodotyrosine; Female; Graves Disease; Humans; Immunoglobulins, Thyroid-Stimulating; Male; Middle Aged; Monoiodotyrosine; ROC Curve; Sensitivity and Specificity; Thyroiditis; Thyrotoxicosis; Thyrotropin; Thyroxine

Topics: Adult; Antigens; Autoantibodies; Biomarkers; Case-Control Studies; Enzyme-Linked Immunosorbent Assay; Female; Graves Disease; Hashimoto Disease; Humans; Hydrogen Peroxide; Male; Malondialdehyde; Middle Aged; Monoiodotyrosine; Oxidation-Reduction; Protein Carbonylation; Thyroid Gland; Thyrotropin

The coupling of iodotyrosine residues of thyroglobulin (Tg) catalysed by thyroid peroxidase (TPO) has scarcely been studied with respect to the TPO of abnormal human thyroid glands. The present paper proposes a rapid and convenient assay method applicable for determining the coupling activity of a sample of less than 500 mg from each patient's thyroid. The main characteristics of the method are as follows: (i) mitochondrial/microsomal fractions of thyroid glands were treated with sodium cholate plus trypsin, and the supernatants obtained by ultracentrifugation were directly used for the assay of coupling and peroxidase activity of TPO; (ii) the formation of iodotyrosine residues catalysed by TPO was performed by using chemically iodinated Graves'-disease Tg containing 41 iodine atoms per molecule and with a high iodotyrosine and a low iodothyronine content; (iii) newly synthesized iodothyronine residues (thyroxine, 3,5,3'-tri-iodothyronine, and 3,3',5'-tri-iodothyronine) were analysed by h.p.l.c. after hydrolysis of Tg with proteinases and extraction of iodothyronines with ethyl acetate.

Topics: Chromatography, High Pressure Liquid; Graves Disease; Humans; Iodide Peroxidase; Methods; Microsomes; Monoiodotyrosine; Thyroglobulin; Thyroid Gland; Thyroxine

The coupling of iodotyrosine (coupling reaction) is one of the least studied in the formation of thyroid hormone, particularly in human thyroid diseases. This paper describes a method of measuring iodotyrosine coupling catalyzed by human thyroid peroxidase (TPO) in vitro. There were two important requirements to demonstrate the coupling reaction: 1) thyroglobulin with a low thyroid hormone content, and 2) partially purified TPO. Thyroglobulin with low thyroid hormone content was obtained from Grave's and follicular adenoma tissues after propylthiouracil (PTU) therapy and L-T4 therapy, respectively. TPO was prepared from Graves' thyroid by solubilizing the 100,000 X g pellet of thyroid homogenate with sodium deoxycholate and trypsin, followed by Sephacryl S-300 gel filtration. Before the coupling reaction, thyroglobulin was iodinated with chloramine-T and potassium iodide, followed by dialysis. The coupling reaction was carried out by incubating newly iodinated thyroglobulin with TPO, diiodotyrosine, a coupling stimulator, and a H2O2-generating system (glucose and glucose oxidase) for 20 min at 37 C. After thyroglobulin was digested with Pronase, the thyroid hormone content of the thyroid digest was measured by RIA. Coupling activity was measured by the amount of newly formed T3 (nanograms of T3 per mg thyroglobulin). The time course of coupling reaction showed a progressive increase in coupling activity up to 30 min, and the reaction was temperature and pH dependent, with a pH optimum of 7.0. Coupling activity in the presence of H2O2 and TPO was 43 +/- 5.0 ng T3/mg thyroglobulin (mean +/- SD of triplicate samples), and addition of diiodotyrosine to the H2O2-TPO system caused a nearly 3-fold increase in coupling activity. This method has potential utilization for measurement of peroxidase coupling activity, since there was a linear relationship between the measured coupling activity and the amount of added TPO when the TPO concentration was over 3 micrograms/300 microliter. Methimazole (MMI) and PTU had similar potencies in inhibiting the TPO-catalyzed coupling reaction, whereas MMI was distinctly more potent than PTU as an inhibitor of TPO-mediated iodination in vitro. The different potencies of MMI in the two reactions suggest that different inhibitory mechanisms may be involved in iodination and coupling. The reducing agent, sodium metabisulfite, was also found to be a more potent inhibitor of the TPO-mediated coupling reaction than of the TPO-mediated

Topics: Catalysis; Chemical Phenomena; Chemistry; Chromatography, Gel; Graves Disease; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Iodide Peroxidase; Methimazole; Monoiodotyrosine; Peroxidases; Propylthiouracil; Sulfites; Temperature; Thyroglobulin; Thyroxine; Triiodothyronine

As a tool with which to detect iodinated compounds in human thyroid specimens, we have reevaluated a nonincineration technique which has so far been employed in the determination of thyroxine-iodine in peripheral blood. The catalytic action of iodoamino acids in the Ce-As reaction was enhanced by a small amount of Cl2. On the contrary, a large amount of Cl2 inhibited the reaction unexpectedly. Among iodide, iodotyrosine and iodothyronine, iodide was the most effective catalyst in the Ce-As reaction and iodothyronine was the least effective one. Protein seemed to inhibit this reaction of thyroglobulin. But the result of iodine content in thyroglobulin by this technique agreed well with that by incineration when measured 127I was corrected by percent activity of dializable part of the total activity of 131I-thyroglobulin with the same protein concentration, after the NaClO treatment. The results of human thyroid specimens were as follows: the thyroglobulin content of five normal subjects was 8.0 +/- 1.5% of wet thyroid weight. That of Hashimoto's disease was significantly decreased which seemed compatible with the decrease in iodine content of thyroglobulin, whereas thyroglobulin content of Graves disease treated with 1-methyl, 2-mercaptoimidazole followed by a large dose of iodide was well preserved in spite of a lower degree of iodination of thyroglobulin. As for the distribution of iodoamino acids-iodine in normal thyroid, T4 was 20.5 +/- 0.7%. This technique ultimately looks promising as a tool with which to study intrathyroidal iodine metabolism in human.

Topics: Adult; Aged; Animals; Diiodotyrosine; Female; Graves Disease; Humans; Iodine; Male; Methods; Middle Aged; Monoiodotyrosine; Rats; Thyroglobulin; Thyroid Gland; Thyroiditis, Autoimmune; Thyroxine; Triiodothyronine

Topics: Adenylyl Cyclases; Adolescent; Adult; Aged; Carbon Radioisotopes; Cyclic AMP; Diiodotyrosine; Female; Glucose; Graves Disease; Humans; Iodine; Iodine Radioisotopes; Male; Middle Aged; Monoiodotyrosine; Phosphoric Diester Hydrolases; Phosphorus; Phosphorus Radioisotopes; Thyroid Gland; Thyrotropin

Topics: Adenylyl Cyclases; Carbon Radioisotopes; Cyclic AMP; Diiodotyrosine; Female; Glucose; Graves Disease; Humans; In Vitro Techniques; Iodine; Iodine Radioisotopes; Monoiodotyrosine; Oxidation-Reduction; Phospholipids; Phosphorus Radioisotopes; Thyroid Gland; Thyrotropin

Topics: Chemical Phenomena; Chemistry; Chromatography, Ion Exchange; Diiodotyrosine; Goiter; Graves Disease; Humans; Iodine; Iodine Isotopes; Methods; Monoiodotyrosine; Potassium Iodide; Spectrophotometry; Thyroglobulin; Thyroid Diseases; Thyroid Gland; Thyroid Neoplasms; Thyroiditis, Autoimmune; Thyroxine; Triiodothyronine

Topics: Autoantibodies; Autoimmune Diseases; Complement Fixation Tests; Graves Disease; Hemagglutination Tests; Humans; Long-Acting Thyroid Stimulator; Monoiodotyrosine; Thyroid Hormones; Thyroiditis; Tyrosine

Topics: Diiodotyrosine; Graves Disease; Humans; Hyperthyroidism; Male; Middle Aged; Monoiodotyrosine; Thyroid Gland; Thyroid Hormones; Thyronines; Thyroxine; Triiodothyronine

Topics: Graves Disease; Humans; Long-Acting Thyroid Stimulator; Monoiodotyrosine; Thyroid Hormones; Tyrosine

Topics: Adult; Blood Proteins; Diiodotyrosine; Female; Graves Disease; Humans; Iodine; Long-Acting Thyroid Stimulator; Middle Aged; Monoiodotyrosine; Myxedema; Protein Binding; Thyroid Hormones; Thyroidectomy; Thyroxine; Tibia; Triiodothyronine; Tyrosine