Author:
Nakashima T.,Inoue K.,Omae T.,Hisatsugu T.,Yoshizumi T.
Abstract
ABSTRACT
The thyroid of Hashimoto's disease is unique in its susceptibility to exogenous iodide and the positive perchlorate test. It would be of interest to know if there is any alteration of iodine metabolism in the thyroid.
The results obtained in 9 cases with untreated Hashimoto's disease were compared with those in 9 normal thyroids; 5 cases were investigated for iodine metabolism and 4 cases for the peroxidase study.
The thyroglobulin content in thyroid wet weight showed lower values 1.6 ± 1.2 % compared to 8.0 ± 1.5 % in normal. Thyroglobulin represented 18.9 ± 9.3 % of total soluble protein and was significantly lower than normal, 66.9 ± 5.4 %. Iodine content of thyroglobulin was extremely low, 0.10 ± 0.05 % compared to 0.49 ± 0.03% in normal. The thyroglobulin with low degree of iodination showed a low sedimentation coefficient of 18.1 ± 0.1. Distribution of iodo-amino acid-iodine was 8.1 ± 2.8% for thyroxine (T4) and 14.4 ± 9.7 % for triiodothyronine (T3), resulting in a much higher T3/T4 ratio than in normal thyroids. Monoiodotyrosine/diiodotyrosine (MIT/DIT) ratio was higher and T4/DIT ratio was apparently lower than normal. These results resemble the pattern of that found in iodine deficiency. T3/T4 ratio was increased in the blood of patients with Hashimoto's disease. Consequently the alteration of distribution of iodo-amino acids in the thyroid may contribute to the increase in T3/T4 ratio in the blood of this disease.
Peroxidase activity showed 103 ± 51 U/mg particulate protein and was significantly lower than values in normal thyroids, 299 ± 85 U/mg protein.
On the other hand, the total amount of thyroglobulin was not significantly decreased in this disease. The total amount of organified iodine, however, was apparently lower than normal.
These results suggest that the low degree of iodination of thyroglobulin is an essential alteration in the thyroid of Hashimoto's disease.
Subject
Endocrinology,General Medicine,Endocrinology, Diabetes and Metabolism
Cited by
8 articles.
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