Inherited Disorders of Thyroid Metabolism*

Abstract

In summary, we have presented a brief survey of the current state of knowledge of inherited disorders of thyroid metabolism. Analysis of cases shows that the biochemical classification covers a wide range of abnormalities and it is likely that further biochemical studies will increase this heterogeneity as well as refining it. Genetic studies are often incomplete, and few in number compared with the classical study by Hutchison and McGirr of Scottish tinker families. Most important, this survey indicates that further research is needed to elucidate the precise molecular mechanisms of the working of the iodide pump, the oxidation and iodination and coupling mechanisms. Study of animal models and DNA sequencing and hybridization work will continue to expand our understanding of abnormalities of thyroglobulin metabolism. We urgently need to find the key to resistance of peripheral and pituitary tissues to thyroid hormone. Subtle dyshormonogenetic abnormalities may await discovery in the field of multinodular goiter and intrathyroidal calcification with goiter. Neonatal screening for hypothyroidism is likely to expand the number of cases for investigation and detailed study. There is an important relationship of dyshormonogenesis to follicular carcinoma. It is hoped that in time we will be able to transform inborn errors into areas of understanding in the realm of the thyroid gland.

Scintigraphic Imaging of Paediatric Thyroid Dysfunction

“…DHG accounts for about 10% of cases of CH and reflects a defect in any of the steps in thyroid hormone synthesis [34, 35]. As a general rule, these defects are responsible for a corresponding rise in the plasma thyrotropin level causing a diffuse goitre which may over time become multinodular.…”

“…The following abnormalities may finally be taken into consideration: (1) reduced or abnormal Tg synthesis [45], which is the most frequent cause [35], (2) impaired colloidal resorption or Tg proteolysis [46], and (3) reduced deiodination process of the iodotyrosines MIT and DIT involving disorders of the DEHAL1 system [12]. In this latter the iodine uptake and turnover are further stimulated by a secondary iodine-deficient state due to excessive renal losses of iode in the form of MIT and DIT.…”

Application of Improved Coupling Assay Method for Peroxidase of Diseased Thyroids: Report of Three Cases.

“…Thus, there are many papers showing that impaired peroxidase in thyroids is related to some thyroid diseases [2,3]. The assay for peroxidase activity in various thyroid diseases has been performed by a number of investigators, but determination of the coupling activity of the enzyme has scarcely been touched on.…”

Familial Goiter in Bongo Antelope (Tragelaphus eurycerus)

“…Albumin in the thyroid has been found to be associated with several different types of thyroid disease, including some cases of congenital goiter (7,8,28). Why albumin is found in some thyroid disorders and not others is not clear, nor is it clear where thyroid albumin is made.…”