Serum Thyroid Hormone and Thyrotropin Levels in Subjects from Endemic Goiter Regions of New Guinea

Chopra, Inder J.; Hershman, Jerome M.; Hornabrook, R. W.

doi:10.1210/jcem-40-2-326

Cited by 108 publications

(50 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, in moderate iodine de®ciency, a reduced serum TSH is observed compared with serum TSH in areas with a lesser degree of iodine de®ciency or iodine suf®ciency. These reduced TSH levels especially among the elderly are in contrast to increased TSH as a direct effect of iodine de®ciency as observed in severe iodine de®ciency (20). This is presumably due to autonomous functioning thyroid tissue, as this regional difference in serum TSH was only found in subjects with nodular glands, and it is in accordance with data from moderate iodine de®ciency in Italy, where decreasing levels of serum TSH were found with increasing degrees of goitre at a clinical examination (21).…”

Section: Discussionsupporting

confidence: 84%

Comparative study of thyroid function and types of thyroid dysfunction in two areas in Denmark with slightly different iodine status

Knudsen

Bülow

Jørgensen

et al. 2000

European Journal of Endocrinology

161

122

View full text Add to dashboard Cite

Objective: The pattern of thyroid dysfunction seems to depend on the iodine status of the population. Prevalence of thyroid dysfunction could be a parameter to consider when evaluating iodine de®ciency disorders in a population. Design: Comparative cross-sectional investigation in two regions in Denmark with marginally different iodine excretion. Methods: A random selection of 4649 participants from the Civil Registration System in Denmark in age groups between 18 and 65 years were examined. Thyroid dysfunction was evaluated from blood samples and questionnaires, and compared with results from ultrasonography. Results: Median iodine excretion was 53 mg/l in Aalborg and 68 mg/l in Copenhagen. Previously diagnosed thyroid dysfunction was found with the same prevalence in the regions. Serum TSH was lower in Aalborg than in Copenhagen (P 0.003) and declined with age in Aalborg, but not in Copenhagen. Not previously diagnosed hyperthyroidism was found with the same overall prevalence in the regions, but in age > 40 years hyperthyroidism was more prevalent in Aalborg (1.3 vs 0.5%, P 0.017). Not previously diagnosed hypothyroidism was found more frequently in Aalborg (0.6 vs 0.2%, P 0.03). Hyperthyroidism was more often associated with macronodular thyroid structure at ultrasound in Aalborg and hypothyroidism was more often associated with patchy thyroid structure in Copenhagen. Conclusions: Signi®cant differences in thyroid dysfunction were found between the regions with a minor difference in iodine excretion. The ®ndings are in agreement with a higher prevalence of thyroid autonomy among the elderly in the most iodine-de®cient region.

show abstract

Section: Discussionsupporting

confidence: 84%

Comparative study of thyroid function and types of thyroid dysfunction in two areas in Denmark with slightly different iodine status

Knudsen

Bülow

Jørgensen

et al. 2000

European Journal of Endocrinology

161

122

View full text Add to dashboard Cite

show abstract

“…[17][18][19] In the present study we found higher TSH levels in goitrous subjects than in nongoitrous ones.…”

supporting

confidence: 53%

Increased goiter prevalence in schoolchildren of Isfahan despite long-term iodine sufficiency

Siavash¹,

Keshteli²,

Hashemipour³

et al. 2009

View full text Add to dashboard Cite

oBJECTIVE: Iodine Deficiency (ID) was for years considered a contributing factor for endemic goiter in Iran. The present study was conducted to assess the goiter prevalence and iodine status in schoolchildren of Isfahan 16 years after the initiation of salt iodization in Iran. DESIGN: 2331 schoolchildren, aged 6-13 years were selected by multistage random sampling. Thyroid size was estimated in each child by inspection and palpation and was graded according to the criteria recommended by WHo. Urinary Iodine Concentration (UIC) was also measured. RE-SULTS: overall, 32.9% of the 2331 students had goiter. 4.6% of them were classified as goitrous grade 2. The median UIC was 195.5μg/l (Range: 10-580μg/l). 15.8% of total samples had iodine excretion level below 100μg/l and 3.7% had iodine level below 50μg/l. UIC in nongoitrous and goitrous children was (mean±SD) 220.91±119.44 μg/l and 220.16±114.64μg/l, respectively (p= 0.949). CoNCLUSIoN: According to the present study there is no biochemical ID and the iodine intake of the total population is adequate. Goiter prevalence has decreased significantly after the new legislation, nevertheless it is still a public health problem in this region. The data suggest that other goitrogens, micronutrient deficiencies and thyroid autoimmunity may be operative and must be investigated in Isfahan schoolchildren.

show abstract

“…This could explain the circumstances in the iodine-deficient rat where an apparently euthyroid state is associated with a low plasma T4, normal plasma T3, and an elevated TSH (17,43). Similar arguments can be applied to explain why patients with endemic goiter, a high plasma TSH, and normal plasma T3 can appear euthyroid as well as why patients with early thyroid dysfunction with reduced plasma T4, normal plasma T3, and elevated TSH are often asvmptomatic in metabolic terms (44)(45)(46)(47). It would appear that the presence of a system in the thyrotroph responsive to decreases in either plasma T, or T4 would provide maximum protection against the onset of metabolic hypothyroidism in tissues such as the liver and kidney whether the threat to the euthyroid state is a result of primary thyroid disease or iodine deficiency.…”

Section: Specific Experimetital Protocolsmentioning

confidence: 91%

Contributions of Plasma Triiodothyronine and Local Thyroxine Monodeiodination to Triiodothyronine to Nuclear Triiodothyronine Receptor Saturation in Pituitary, Liver, and Kidney of Hypothyroid Rats

Silva¹,

Larsen²

1978

J. Clin. Invest.

209

View full text Add to dashboard Cite

A B S T R A C T Inijections of triiodothyronine (T3)and thyroxine (T4) into chronically hypothyroid rats were used to evaluate the contribution of intracellular T4 to T3 conversion to nuclear T3 in pituitary, liver, and kidney, and to correlate the occupancy of pituitary nuclear T3 receptors with inhibition of thyroid-stimulating hormone (TSH) release. Injection of a combination of 70 ng T3 and 400 ng T4/100 g body wt resulted in plasma T3 concentrations of 45+7 ng/dl (mean±+-SD) and 3.0±0.4,ug/dl T43 h later. At that plasma T3 level, the contribution of plasma T3 to the nuclear receptor sites resulted in saturation of 34±7% for pituitary, 27±5% for liver, and 33+2% for kidney. In addition to the T3 derived from plasma T3, there was additional T3 derived from intracellular monodeiodination of T4 in all three tissues that resulted in total nuclear occuipancy (as percent saturation) of 58±11% (pituitary), 36±8% (liver), and 41+11% (kidney), respectively. The percent contribution of T3 derived from cellular T4 added 41% of the total nuclear T3 in the pituitary which was significantly higher than the contribution of this source in the liver (24%) or the kidney (19%). 3 h after intravenous injection of increasing doses of T3, the plasma T3 concentration correlated well with both the change in TSH and the nuclear occupancy, suggesting a linear relationship between the integrated nuclear occupancy by T3 and TSH release rate. The contribution of intrapituitary T4 to T3 conversion to nuclear T, was accompanied by an appropriate decrease in TSH, supporting the biological relevance of nuclear T3. Pretreatment of the animals with 6-n-propylthiouracil before T4 injection decreased neither the nuclear T3 derived from intrapituitary T4 nor the subsequent decrease in TSH.These results indicate that intracellular monodeiodination of T4 contributes substantially to the nuclear T3 in the pituitary of the hypothyroid rat, and suggest a linear inverse relationship between nuclear receptor occupancy by T3 in the pituitary and TSH release rate. The data further indicate that T4 to T3 monodeiodination is considerably more important as a source of nuclear T3 in the pituitary than in the liver and kidney. This provides a mechanism whereby the TSH secretion could respond promptly to a decrease in thyroid secretion (predominantly T4) before a decrease in plasma T3 would be expected to lead to significant metabolic hypothyroidism. INTRODUCTIONThere is considerable indirect evidence suggesting that interaction of triiodothyronine (T3)l with a specific

show abstract

Serum Thyroid Hormone and Thyrotropin Levels in Subjects from Endemic Goiter Regions of New Guinea

Cited by 108 publications

References 0 publications

Comparative study of thyroid function and types of thyroid dysfunction in two areas in Denmark with slightly different iodine status

Comparative study of thyroid function and types of thyroid dysfunction in two areas in Denmark with slightly different iodine status

Increased goiter prevalence in schoolchildren of Isfahan despite long-term iodine sufficiency

Contributions of Plasma Triiodothyronine and Local Thyroxine Monodeiodination to Triiodothyronine to Nuclear Triiodothyronine Receptor Saturation in Pituitary, Liver, and Kidney of Hypothyroid Rats

Contact Info

Product

Resources

About