<b>Immunological and chemical types of reversible hypothyroidism; clinical characteristics and long‐term prognosis</b>

Sato, Kaori; Okamura, Ken; Hirata, Tsuneo; Yamasaki, Kouji; Ikenoue, Hiroshi; Kuroda, Takeo; Mizokami, Tetsuya; Inokuchi, Kaeko; Fujishima, Masatoshi

doi:10.1046/j.1365-2265.1996.00858.x

Cited by 23 publications

(23 citation statements)

References 31 publications

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“…However, this autoregulation is not perfect and commonly induces some degree of thyroid hypofunction. In Japanese adults with chronic excess iodine intakes, many with overt hypothyroidism will become euthyroid if their iodine intakes are normalized (277,278). The other proposed mechanism is induction of thyroid hypofunction due to iodine-induced autoimmune thyroiditis (279), although not all studies agree (82,83).…”

Section: A Cross-sectional Studies: the Epidemiology Of Thyroid Disomentioning

confidence: 97%

Iodine Deficiency

2009

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Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected. However, about 50% of Europe remains mildly iodine deficient, and iodine intakes in other industrialized countries, including the United States and Australia, have fallen in recent years. Iodine deficiency during pregnancy and infancy may impair growth and neurodevelopment of the offspring and increase infant mortality. Deficiency during childhood reduces somatic growth and cognitive and motor function. Assessment methods include urinary iodine concentration, goiter, newborn TSH, and blood thyroglobulin. But assessment of iodine status in pregnancy is difficult, and it remains unclear whether iodine intakes are sufficient in this group, leading to calls for iodine supplementation during pregnancy in several industrialized countries. In most countries, the best strategy to control iodine deficiency in populations is carefully monitored universal salt iodization, one of the most cost-effective ways to contribute to economic and social development. Achieving optimal iodine intakes from iodized salt (in the range of 150-250 microg/d for adults) may minimize the amount of thyroid dysfunction in populations. Ensuring adequate iodine status during parenteral nutrition has become important, particularly in preterm infants, as the use of povidone-iodine disinfectants has declined. Introduction of iodized salt to regions of chronic iodine deficiency may transiently increase the incidence of thyroid disorders, but overall, the relatively small risks of iodine excess are far outweighed by the substantial risks of iodine deficiency.

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Section: A Cross-sectional Studies: the Epidemiology Of Thyroid Disomentioning

confidence: 97%

Iodine Deficiency

2009

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“…However, the autoregulation is far from perfect and often tends to induce thyroid hypofunction. In areas with a high iodine intake, such as Japan, a considerable proportion of patients with newly diagnosed overt hypothyroidism will become euthyroid if they normalize their iodine intake (73)(74)(75)(76).…”

Section: Mechanisms Behind the High Prevalence Of Elevated Serum Tsh mentioning

confidence: 99%

Environmental Iodine Intake Affects the Type of Nonmalignant Thyroid Disease

Laurberg¹,

Pedersen²,

Knudsen³

et al. 2001

Thyroid

258

162

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The relationship between the iodine intake level of a population and the occurrence of thyroid diseases is U-shaped with an increase in risk from both low and high iodine intakes. Developmental brain disorders and endemic goiter caused by severe iodine deficiency may seriously deteriorate overall health status and economic performance of a population. Severe iodine deficiency with a median 24-hour urinary iodine excretion of the population below 25 microg needs immediate attention and correction. Less severe iodine deficiency with median urinary iodine excretion below 120 microg per 24 hours is associated with multinodular autonomous growth and function of the thyroid gland leading to goiter and hyperthyroidism in middle aged and elderly subjects. The lower the iodine intake, the earlier and more prominent are the abnormalities. At the other end of the spectrum, severely excessive iodine intake starting at median urinary iodine excretion levels around 800 microg per 24 hours is associated with a higher prevalence of thyroid hypofunction and goiter in children. A number of studies indicate that moderate and mild iodine excess (median urinary iodine >220 microg per 24 hours) are associated with a more frequent occurrence of hypothyroidism, especially in elderly subjects. The exact mechanism leading to this has not been clarified, and more studies are needed to define the limits of excessive iodine intake precisely. Due to the frequent occurrence of thyroid disorders, proper monitoring and control of the population iodine intake level is a cost-effective alternative to diagnosing, therapy and control of the many individual cases of thyroid diseases that might have been prevented.

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“…However, the presence of goiter, RAIU and serum Tg level, which may reflect the number of preserved thyroid follicles, are less useful in Hashimoto's thyroiditis as compared with iodide-induced hypothyroidism [20]. In addition, RAIU and thyroid ultrasonography are time consuming and require the special apparatuses, letting themselves performed only in limited numbers of clinics.…”

Section: Discussionmentioning

confidence: 99%

Erythrocyte zinc concentration as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism from permanent hypothyroidism

et al. 2011

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There are two clinical presentations of hypothyroidism, permanent hypothyroidism (PH) and transient hypothyroidism (TH). PH patients require a lifelong T4 supplementation. In contrast, TH spontaneously resolves within several months and therefore TH patients basically need no or short-term supplementation. abstract. Red blood cell (RBC) zinc (Zn) concentration reflects a patient's mean thyroid hormone level over the preceding several months. The aim of this study was to examine whether RBC Zn level can be used as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism (TH) from permanent hypothyroidism (PH). RBC Zn level was measured in 30 untreated PH patients with Hashimoto's thyroiditis and 7 untreated TH patients with painless thyroiditis in whom preceding transient thyrotoxicosis had been confirmed. RBC Zn concentration was significantly lower in TH patients than that in PH patients. There was a positive correlation between RBC Zn and serum TSH, and the latter was clearly lower in TH patients than that in PH patients. However, RBC Zn level was again significantly lower in TH patients than PH patients despite of the comparable serum TSH levels in both groups when RBC Zn was evaluated in patients with serum TSH levels of less than 50 mU/L. Thus TH patients could be identified with RBC Zn measurement, allowing us avoidance of unnecessarily prolonged T4 administration to them.Key words: Hypothyroidism, Zinc, Red blood cell, Painless thyroiditis However, there are few indicators that can be used for this purpose.Thyroid hormone inhibits the synthesis of red blood cell (RBC) carbonic anhydrase I (CAI) [6] with which most of zinc (Zn) in RBC is associated [7], thus decreasing RBC Zn concentrations [8]. We have previously shown that patients with Graves' hyperthyroidism have a RBC Zn level clearly lower than that of patients with destructive thyroiditis [9,10]. Our data have therefore demonstrated that the RBC Zn concentration reflects a patient's mean thyroid hormone level over the preceding several months as glycosylated hemoglobin level does in diabetic patients [11]. In contrast, RBC Zn levels in hypothyroid patients have received less attention. In our previous studies [9], hypothyroid patients have a RBC Zn concentration similar to that of healthy controls. However, RBC Zn level was not measured individually in each form of hypothyroidism. Considering the thyroid hor-

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Immunological and chemical types of reversible hypothyroidism; clinical characteristics and long‐term prognosis

Abstract: Thyroid damage was more severe, recovery slower and the rate of relapse higher in the immunological than in the chemical type of reversible hypothyroidism.

Cited by 23 publications

References 31 publications

Iodine Deficiency

Iodine Deficiency

Environmental Iodine Intake Affects the Type of Nonmalignant Thyroid Disease

Erythrocyte zinc concentration as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism from permanent hypothyroidism

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