scholarly journals Increased sensitivity to the inhibitory effect of excess iodide on thyroid function in patients with beta-thalassemia major and iron overload and the subsequent development of hypothyroidism

2000 ◽  
pp. 319-325 ◽  
Author(s):  
T Alexandrides ◽  
N Georgopoulos ◽  
S Yarmenitis ◽  
AG Vagenakis
Keyword(s):  
Thyroid Hormone ◽  
Iron Overload ◽  
Thyroid Function ◽  
Subclinical Hypothyroidism ◽  
Beta Thalassemia ◽  
Normal Response ◽  
Normal Thyroid ◽  
Increased Sensitivity ◽  
Excess Iodide ◽  
Tsh Levels

OBJECTIVE: Patients with beta-thalassemia frequently develop primary hypothyroidism and other endocrine disorders due to iron overload. We studied whether administration of excess iodide to patients with apparently normal thyroid function could uncover an underlying thyroid disease. DESIGN AND METHODS: Twenty-five patients, 10 prepubertal (mean age 11+/-3 years) and 15 adults (mean age 23+/-5 years) with normal thyroid hormone and TSH levels, a normal response of TSH to TRH and negative thyroid peroxidase antibodies received 20mg iodide three times daily for three weeks, and thyroid hormone and TSH levels were measured weekly during, and for three weeks after, iodide administration and every 3 months thereafter for the next 5 years. RESULTS: During iodide administration there was a significant decrease in thyroid hormone concentrations which remained within normal levels, and a significant increase in TSH concentrations which in 14 out of 25 (56%) patients reached the hypothyroid level. Baseline TSH values were higher in those patients who developed subclinical hypothyroidism (2.31+/-0.71mU/l vs 1. 34+/-0.64mU/l, P=0.0016). Subclinical hypothyroidism developed in 70% of prepubertal and in 47% of adult patients. Serum ferritin was elevated in all patients. Nine of the fourteen patients (64.3%) who developed subclinical hypothyroidism during iodide administration developed hypothyroidism during the 5-year follow-up compared with only one of the eleven patients with a normal response to iodide (P=0.004). CONCLUSIONS: Patients with beta-thalassemia should not be exposed to excess iodide due to increased sensitivity to its inhibitory effects on thyroid function. The susceptible individuals frequently develop permanent hypothyroidism in the following years.

EFFECT OF THYROID STATUS ON THE THYROTROPHIN-RELEASING HORMONE-DEGRADING ACTIVITY OF RAT SERUM

1976 ◽  
Vol 71 (1) ◽  
pp. 13-19 ◽  
Author(s):  
N. WHITE ◽  
S. L. JEFFCOATE ◽  
E. C. GRIFFITHS ◽  
K. C. HOOPER
Keyword(s):  
Thyroid Hormone ◽  
Human Serum ◽  
Thyroid Function ◽  
Thyroid Status ◽  
Rat Serum ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Tsh Levels

SUMMARY The TRH-degrading activity of rat serum in vitro is five times more potent than that of human serum. In rats, it is significantly reduced in hypothyroidism (thiouracil-induced) and significantly increased in hyperthyroidism (T3 or T4-induced). This suggests a possible role in the regulation of adenohypophysial-thyroid function which is probably, in turn, dependent on thyroid hormone, rather than TSH, levels.

scholarly journals Thyroid Function in Chronically Transfused Children with Beta Thalassemia Major: A Cross-Sectional Hospital Based Study

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Suraj Haridas Upadya ◽  
M. S. Rukmini ◽  
Sowmya Sundararajan ◽  
B. Shantharam Baliga ◽  
Nutan Kamath
Keyword(s):  
Thyroid Function ◽  
Serum Ferritin ◽  
Subclinical Hypothyroidism ◽  
Thyroid Dysfunction ◽  
Genetic Disorder ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
P Value ◽  
Blood Transfusions ◽  
Beta Thalassemia Major

Background. Thalassemia is the most common genetic disorder worldwide. Use of iron chelators has improved survival but endocrine complications have become more frequent. The frequency of hypothyroidism in Beta Thalassemia Major (BTM) children ranges from 6 to 30 %. Thyroid dysfunction mainly occurs by gland infiltration, chronic tissue hypoxia, free radical injury, and organ siderosis. Objectives. (a) To evaluate the thyroid function status in chronically transfused children with BTM, in the first and second decade of life and (b) to study the influence of factors like duration and amount of blood transfusions, serum ferritin level, and iron chelation therapy on thyroid function. Methodology. BTM children, 3 years old and above, on regular blood transfusions with serum ferritin > 1500 mcg/l were included in the study. Thyroid function and ferritin assessment was done using ELISA kits. Autoimmune thyroiditis was ruled out by antithyroid peroxidase and antithyroglobulin antibody testing. Results. A study population of 83 children consisted of 49 boys (59%) and 34 girls (41%). 4.8% of the children had evidence of subclinical hypothyroidism. Among them two belonged to the first decade and the other two to the second decade of life. Mean TSH, FT4, and ferritin values among children with thyroid dysfunction were 6.38 ± 0.83 mIU/ml, 1.08 ± 0.45 ng/dl, and 3983.0±1698.30 ng/ml, respectively. The severity of thyroid dysfunction was statistically significantly associated with higher serum TSH values in children in the second decade of life with a p value = 0.001. No other significant correlation was found between oral chelation, amount and duration of blood transfusion, or serum ferritin levels. Conclusion. Subclinical hypothyroidism was the thyroid dysfunction observed in our study. Regular blood transfusions with adequate chelation may decrease incidence of thyroid dysfunction.

scholarly journals The Effects of Amiodarone on Thyroid Function in Pediatric and Young Adult Patients

2019 ◽  
Vol 104 (11) ◽  
pp. 5540-5546 ◽  
Author(s):  
Brett Barrett ◽  
Colin P Hawkes ◽  
Amber Isaza ◽  
Andrew J Bauer
Keyword(s):  
Young Adults ◽  
Young Adult ◽  
Thyroid Hormone ◽  
Thyroid Function ◽  
Subclinical Hypothyroidism ◽  
Thyroid Dysfunction ◽  
Adult Population ◽  
Hormone Replacement ◽  
Common Adverse Effect ◽  
Children And Young Adults

Abstract Context Amiodarone is used in patients with arrhythmias, but thyroid dysfunction [amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH)] is a common adverse effect. As the onset of AIT and AIH has not been studied in children, the timing of dysfunction and long-term monitoring are not known in this population. Objective To describe the incidence and timing of amiodarone-induced thyroid dysfunction in children and adolescents, with a secondary aim to identify risk factors for amiodarone-induced thyroid dysfunction, and to identify variance in thyroid hormone surveillance and treatment. Design Retrospective review of thyroid dysfunction in children and young adults treated with amiodarone between 2007 and 2018. Setting Children’s Hospital of Philadelphia. Patients Children and young adults treated with amiodarone. Main Outcome Measures Prevalence of amiodarone-induced thyroid dysfunction. Results Of 484 patients, 190 had thyroid-function testing; 17.3% were found to have subclinical hypothyroidism, and 13.7% testing developed hypothyroidism. Hyperthyroidism occurred in 2.1%. In patients with subclinical hypothyroidism, 63% returned to normal thyroid function without thyroid hormone replacement. Only 26% of patients with hypothyroidism had spontaneous normalization of thyroid function. Twenty-five percent of AIT patients had spontaneous normalization of thyroid function. Conclusions This study looks at a pediatric and young-adult population in an effort to describe the natural history of amiodarone-induced thyroid dysfunction. Based on our data, we recommend that a complete thyroid-function panel be obtained within the first week and then at weekly intervals for the first 5 weeks after initiation. The majority of thyroid dysfunction was noted within the first 35 days of treatment.

scholarly journals Effect of small doses of iodine on thyroid function in patients with Hashimoto's thyroiditis residing in an area of mild iodine deficiency

1998 ◽  
pp. 23-28 ◽  
Author(s):  
W Reinhardt ◽  
M Luster ◽  
KH Rudorff ◽  
C Heckmann ◽  
S Petrasch ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Iodine Deficiency ◽  
Subclinical Hypothyroidism ◽  
Hashimoto’S Thyroiditis ◽  
Thyroid Volume ◽  
Treated Group ◽  
Hashimoto's Thyroiditis ◽  
Control Group ◽  
Small Doses

OBJECTIVE: Several studies have suggested that iodine may influence thyroid hormone status, and perhaps antibody production, in patients with autoimmune thyroid disease. To date, studies have been carried out using large amounts of iodine. Therefore, we evaluated the effect of small doses of iodine on thyroid function and thyroid antibody levels in euthyroid patients with Hashimoto's thyroiditis who were living in an area of mild dietary iodine deficiency. METHODS: Forty patients who tested positive for anti-thyroid (TPO) antibodies or with a moderate to severe hypoechogenic pattern on ultrasound received 250 microg potassium iodide daily for 4 months (range 2-13 months). An additional 43 patients positive for TPO antibodies or with hypoechogenicity on ultrasound served as a control group. All patients were TBII negative. RESULTS: Seven patients in the iodine-treated group developed subclinical hypothyroidism and one patient became hypothyroid. Three of the seven who were subclinically hypothyroid became euthyroid again when iodine treatment was stopped. One patient developed hyperthyroidism with a concomitant increase in TBII titre to 17 U/l, but after iodine withdrawal this patient became euthyroid again. Only one patient in the control group developed subclinical hypothyroidism during the same time period. All nine patients who developed thyroid dysfunction had reduced echogenicity on ultrasound. Four of the eight patients who developed subclinical hypothyroidism had TSH concentrations greater than 3 mU/l. In 32 patients in the iodine-treated group and 42 in the control group, no significant changes in thyroid function, antibody titres or thyroid volume were observed. CONCLUSIONS: Small amounts of supplementary iodine (250 microg) cause slight but significant changes in thyroid hormone function in predisposed individuals.

THYROID FUNCTION IN RATS ADMINISTERED EXCESS IODIDE

1972 ◽  
Vol 69 (2) ◽  
pp. 321-328
Author(s):  
K. Liewendahl ◽  
E. Niskanen ◽  
A. Gordin
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Chronic Administration ◽  
Free Thyroxine ◽  
Hormone Synthesis ◽  
Histological Alterations ◽  
Thyroid Hormone Synthesis ◽  
Excess Iodide ◽  
And Function

ABSTRACT The effects of excess iodide on the histology and function of the thyroid were studied in rats. A slight increase in thyroid weight and minimal histological alterations were observed. The thyroid function of rats was studied by measuring the serum total and free thyroxine. Excess iodide did not significantly change the concentration of thyroid hormone in the serum and signs of hypothyroidism were not seen. Thus, rats were capable of adaptation to chronic administration of large amounts of iodide. A slight increase in the serum thyrotrophin after prolonged ingestion of excess iodide was measured with both bioassay and radioimmunoassay techniques. The possible role of thyrotrophin in the mechanism of escape from the transient inhibition of iodide on thyroid hormone synthesis is discussed.

scholarly journals Management of subclinical hypothyroidism in pregnancy: are we too simplistic?

2015 ◽  
Vol 173 (1) ◽  
pp. P1-P11 ◽  
Author(s):  
Georg Brabant ◽  
Robin P Peeters ◽  
Shiao Y Chan ◽  
Juan Bernal ◽  
Philippe Bouchard ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Subclinical Hypothyroidism ◽  
Serum Levels ◽  
Clear Understanding ◽  
Specific Antibodies ◽  
Hormone Transport ◽  
Limited Experience ◽  
Pregnant State ◽  
Tsh Levels ◽  
In Pregnancy

Guideline advice of many societies on the management of subclinical hypothyroidism in pregnancy suggests treatment when TSH serum levels exceed 2.5 mU/l. Justification of this procedure is based on limited experience, mainly from studies carried out in patients with positive thyroid-specific antibodies and higher TSH levels that classically define the condition in the non-pregnant state. Taking into account a lack of clear understanding of the regulation of thyroid hormone transport through the utero-placental unit and in the absence of foetal markers to monitor the adequacy of thyroxine treatment, this review attempts to discuss currently available data and suggests a more cautious approach.

scholarly journals Correlation Between the Thyroid Hormone Levels and Nonalcoholic Fatty Liver Disease in Type 2 Diabetic Patients with Normal Thyroid Function

2020 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Huaizhen Liu ◽  
Juyi Li ◽  
Ling Li ◽  
Jinjun Zhang ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Liver Fibrosis ◽  
Thyroid Function ◽  
Fatty Liver Disease ◽  
Nonalcoholic Fatty Liver ◽  
Normal Thyroid ◽  
Hormone Levels ◽  
Normal Thyroid Function ◽  
Thyroid Hormone Levels

Abstract Background: The objective of this study is to retrospectively analyze the correlation between the thyroid hormones and nonalcoholic fatty liver disease (NAFLD) in type 2 diabetes mellitus (T2DM) patients with normal thyroid function. Methods: Totally 586 T2DM patients with normal thyroid function participated in this research and were divided into T2DM without NAFLD (240 cases) group and T2DM with NAFLD (346 cases) group. The NAFLD fibrosis score (NFS) >0.676 was defined as progressive liver fibrosis and used to categorize the patients into T2DM without progressive liver fibrosis group (493 cases) and T2DM with progressive liver fibrosis group (93 cases). Results: The results indicated that the levels of free triiodothyronine (FT3) and total triiodomethylamine (TT3) were significantly higher while the free thyroxine (FT4) level was lower in T2DM with NAFLD group than that in T2DM2 without NAFLD group (p<0.05). The levels of FT3, FT4 and TT3 in patients with progressive liver fibrosis were significantly lower in patients with progressive liver fibrosis than that in patients without progressive liver fibrosis (p<0.05). Logistic regression analysis showed a negative relationship between FT4 level and NAFLD (p=0.026), between the levels of FT4,TT3 and total thyroxine (TT4) and the risk of progressive hepatic fibrosis (p=0.022, p=0.007,p=0.046).Conclusion: There is a certain correlation between thyroid hormone levels and NAFLD in T2DM patients, suggesting that the assessment of thyroid hormone levels in T2DM patients with normal thyroid function is of great significance in the prevention and treatment of NAFLD.

Reversal of Hypothyroidism in Well Chelated β-Thalassemia Major Patients

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3884-3884
Author(s):  
Kallistheni Farmaki ◽  
Ioanna Tzoumari ◽  
Christina Pappa
Keyword(s):  
Thyroid Gland ◽  
Iron Overload ◽  
Thyroid Function ◽  
Thalassemia Major ◽  
Stimulation Test ◽  
Overt Hypothyroidism ◽  
Trh Stimulation ◽  
Increased Risk ◽  
The Mean ◽  
Tsh Levels

Abstract Thyroid dysfunction is known to occur frequently in β-Thalassemia major patients (TMps), but its prevalence and severity varies in different cohorts according to chelation regimens. Thyroid hormones are critical determinants of brain and somatic development in infants and of metabolic activity in adults affecting the function of virtually every organ system. Thyroid gland mainly secrets T4, whereas 80% of T3 is produced by de-iodination of T4 (liver, kidney, heart and other tissues) and is influenced by a variety of factors. Furthermore, T4 & T3 secretion is tightly regulated within narrow limits by a mechanism that involves the pituitary-secreted TSH which in turn is stimulated by the hypothalamic TRH. Thus, iron overload-related hypothyroidism may be either central (because of deposition in the pituitary or the hypothalamus) and usually associated with other endocrinopathies, or primary (by deposition in the thyroid gland or even other organs). Existing data suggest that the thyroid gland appears to fail before the central components of the axis. In all cases, symptoms occur slowly over time and may vary from subclinical to overt hypothyroidism which is associated with an increased risk of cardiovascular disease. The aim of this study was to investigate the effect of long-term intensive combined chelation therapy on thyroid function in TMps after they were all in negative iron balance. 51 TMps, 25 males 26 females, mean age 29.8±2.03, who were previously maintained on subcutaneous desferrioxamine monotherapy (DFO:40mg/kg, 3–6 days/week) switched to an intensive combined chelation with DFO (40–60mg/kg/d) and Deferiprone (DFP: 75–100mg/kg/d) adapted to individual needs. Thyroid function was assessed initially and after 6 years by TRH stimulation test and TSH, FT4 & FT3 screening. All patients on hormone replacement therapy stopped treatment at least 30 days before the test. This was approved by the Hospital Scientific Committee. Criteria for the diagnosis of subclinical or compensated hypothyroidism was an increase of the TSH levels during the test of more than 20 μIU/ml from the basal value or an elevated basal TSH concentration (>5 μIU/ml) and for overt hypothyroidism a further decrease in FT4 & FT3 levels. With DFO monotherapy 18 TMps were treated with thyroxin therapy. In these patients after combined chelation and an important decrease in iron overload (p<0.0001) as estimated by ferritin levels (2,737±473 vs 450±225mg/dl), MRI liver and heart iron quantification (T2*L & T2*H) and LIC calculated by Ferriscan (13±3 vs. 1.4±0.5mg/gdw), a significant increase was observed in mean FT4 (1.07±0.03 vs. 0.7±0.02ng/ml, p<0.0001) & mean FT3 (2.6±0.1 vs. 1.3± 0.1pg/ml, p<0.0001) and an additional significant decrease in the mean TSH quantitative secretion, calculated as the area under the curve (AUC=1,332±131 vs. 2,231±241, p<0.0001). These 10/18 (56%) TMps with subclinical or compensated hypothyroidism, who normalized TSH, FT4 & FT3 levels and had a normal TRH stimulation test discontinued thyroxin therapy, while another 4/18 (22%) reduced their thyroxin dose. The remaining 4/18 with overt hypothyroidism, while they all improved their TRH stimulation test, only 2 improved to compensated hypothyroidism with TSH levels 5–10mIU/ml and normal FT4 & FT3 levels. Critically, in the other 33/51 euthyroid TMps, no new cases of hypothyroidism were noted after combined chelation and a significant increase (p<0.0001) was observed in the mean FT4 & FT3 levels with a significant decrease (p<0.0001) in the mean TSH quantitative secretion (AUC). This study showed that intensive combined chelation associated with a significant decrease of iron overload may reverse some cases of primary hypothyroidism, either subclinical or compensated, and may prevent progression to overt hypothyroidism, thus influencing the decision to treat with thyroid hormone. It may also improve some cases of overt hypothyroidism suggesting that even iron-induced damage of the thyroid pituitary axis might be ameliorated.

scholarly journals Mild Anemia May Affect Thyroid Function in Pregnant Chinese Women During the First Trimester

2021 ◽  
Vol 12 ◽  
Author(s):  
Guan-ying Nie ◽  
Rui Wang ◽  
Peng Liu ◽  
Ming Li ◽  
Dian-jun Sun
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Normal Control ◽  
Subclinical Hypothyroidism ◽  
First Trimester ◽  
Specific Reference ◽  
American Thyroid Association ◽  
Mild Anemia ◽  
Upper Limit ◽  
Tsh Levels

BackgroundPregnant women are often susceptible to anemia, which can damage the thyroid gland. However, compared with moderate and severe anemia, less attention has been paid to mild anemia. The purpose of this study was to evaluate the effect of mild anemia on the thyroid function in pregnant women during the first trimester.MethodsA total of 1,761 women in the first trimester of their pregnancy were enrolled from Shenyang, China, and divided into mild anemia and normal control groups based on their hemoglobin levels. Thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) levels were compared between the two groups.ResultsThe TSH levels of pregnant women with mild anemia were higher than those of pregnant women without mild anemia (p &lt; 0.05). Normal control women were selected to set new reference intervals for TSH, FT3, and FT4 levels during the first trimester, which were 0.11–4.13 mIU/l, 3.45–5.47 pmol/l, and 7.96–16.54 pmol/l, respectively. The upper limit of TSH 4.13 mU/l is close to the upper limit 4.0 mU/l recommended in the 2017 American Thyroid Association (ATA) guidelines, indicating that exclusion of mild anemia may reduce the difference in reference values from different regions. Mild anemia was related to 4.40 times odds of abnormally TSH levels (95% CI: 2.84, 6.76) and 5.87 increased odds of abnormal FT3 (95% CI: 3.89, 8.85). The proportion of hypothyroidism and subclinical hypothyroidism in patients with mild anemia was higher than that in those without anemia (0.6% vs. 0, p = 0.009; 12.1% vs. 1.9%, p &lt; 0.001). Mild anemia was related to 7.61 times increased odds of subclinical hypothyroidism (95% CI: 4.53, 12.90).ConclusionsMild anemia may affect thyroid function during the first trimester, which highlights the importance of excluding mild anemia confounding when establishing a locally derived specific reference interval for early pregnancy.

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