scholarly journals The different requirement of l-T4 therapy in congenital athyreosis compared with adult-acquired hypothyroidism suggests a persisting thyroid hormone resistance at the hypothalamic–pituitary level

2014 ◽  
Vol 171 (5) ◽  
pp. 615-621 ◽  
Author(s):  
Brunella Bagattini ◽  
Caterina Di Cosmo ◽  
Lucia Montanelli ◽  
Paolo Piaggi ◽  
Mariella Ciampi ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Total Thyroidectomy ◽  
Replacement Therapy ◽  
Adult Patients ◽  
Hormone Deficiency ◽  
Fetal Life ◽  
Free Thyroid Hormones ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Design And Methods

BackgroundLevothyroxine (l-T4) is commonly employed to correct hormone deficiency in children with congenital hypothyroidism (CH) and in adult patients with iatrogenic hypothyroidism.ObjectiveTo compare the daily weight-based dosage of the replacement therapy withl-T4in athyreotic adult patients affected by CH and adult patients with thyroid nodular or cancer diseases treated by total thyroidectomy.Design and methodsA total of 36 adult patients (27 females and nine males) aged 18–29 years were studied; 13 patients (age: 21.5±2.1, group CH) had athyreotic CH treated withl-T4since the first days of life. The remaining 23 patients (age: 24±2.7, group AH) had hypothyroidism after total thyroidectomy (14 patients previously affected by nodular disease and nine by thyroid carcinoma with clinical and biochemical remission). Patient weight, serum free thyroid hormones, TSH, thyroglobulin (Tg), anti-Tg, and anti-thyroperoxidase antibodies were measured. Requiredl-T4dosage was evaluated. At the time of the observations, all patients presented free thyroid hormones within the normal range and TSH between 0.8 and 2 μIU/ml.ResultsPatients had undetectable Tg and anti-thyroid antibodies. The daily weight-based dosage of the replacement therapy withl-T4to reach euthyroidism in patients of group CH was significantly higher than that in those of group AH (2.16±0.36 vs 1.73±0.24 μg/kg,P<0.005). Patients of group CH treated withl-T4had significantly higher serum TSH levels than patients of group AH (P=0.05) as well as higher FT4concentrations.ConclusionsTo correct hypothyroidism, patients of group CH required a dailyl-T4dose/kg higher than group AH patients, despite higher levels of TSH. The different requirement of replacement therapy between adult patients with congenital and those with surgical athyroidism could be explained by a lack of thyroid hormones since fetal life in CH, which could determine a different set point of the hypothalamus–pituitary–thyroid axis.

scholarly journals The pituitary-thyroid axis in healthy men living under subarctic climatological conditions

2001 ◽  
Vol 169 (1) ◽  
pp. 195-203 ◽  
Author(s):  
J Hassi ◽  
K Sikkila ◽  
A Ruokonen ◽  
J Leppaluoto
Keyword(s):  
Thyroid Hormones ◽  
Climatic Factors ◽  
Feedback Mechanism ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Healthy Men ◽  
Non Invasive ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh

In order to evaluate the effects of climatic factors on the secretion of thyroid hormones and TSH in a high latitude population, we have taken serum and urine samples from 20 healthy men from northern Finland (67 degrees -68 degrees N) every 2 months for a period of 14 months. Serum free triiodothyronine (T(3)) levels were lower in February than in August (3.9 vs 4.4 pmol/l, P<0.05) and TSH levels were higher in December than during other months (2.1 vs 1.5-1.7 mU/l, P<0.01). Serum total and free thyroxine (T(4)), total T(3) and reverse T(3) levels and urinary T(4) levels were unchanged. Urinary T(3) levels were significantly higher in winter than in summer. Serum free T(3) correlated highly significantly with the outdoor temperature integrated backwards weekly for 7-56 days (r=0.26 for 1-56 days) from the day when the blood samples were taken. Serum TSH did not show any significant correlation with the thyroid hormones or with the integrated temperature of the previous days, but it did show an inverse and significant correlation (r=-0.31) with the ambient luminosity integrated backwards for 7 days from the day when the blood sample was taken. The gradually increasing correlation between outdoor temperatures and serum free T(3) suggests that the disposal of thyroid hormones is accelerated in winter, leading to low serum free T(3) levels and a high urinary free T(3) excretion. Since there was no correlation between thyroid hormones and serum TSH, the feedback mechanism between TSH and thyroid hormones may not be the only contributing factor, and other factors such as ambient luminosity may at least partly determine serum TSH in these conditions. Also urinary free T(3) appears to be a novel and non-invasive indicator for thyroid physiology.

scholarly journals Thyroid hormones modulate irisin concentrations in patients with recently onset hypothyroidism following total thyroidectomy

2020 ◽  
Author(s):  
R. Bocale ◽  
A. Barini ◽  
A. D‘Amore ◽  
M. Boscherin ◽  
S. Necozione ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Thyroid Hormones ◽  
Total Thyroidectomy ◽  
Replacement Therapy ◽  
Thyroid Function ◽  
Multivariate Regression ◽  
Multivariate Regression Analysis ◽  
Levothyroxine Replacement ◽  
Circulating Levels

Abstract Purpose Irisin is a newly discovered adipo-myokine known for having significant effects on body metabolism. Currently, there is a discussion regarding the relation between thyroid function and irisin concentration. This study was designed to evaluate the influential role of levothyroxine replacement therapy on circulating levels of irisin in patients with recently onset hypothyroidism following total thyroidectomy. Methods Circulating levels of thyroid hormones, irisin and other metabolic parameters, were assessed in 40 recently thyroidectomized patients (34 females, mean age 50.1 ± 15.2 years) at baseline (5–7 day after surgery) and after 2 months under replacement therapy with levothyroxine. Results At baseline, circulating levels of thyroid hormones were indicative of hypothyroidism (TSH 12.7 ± 5.0 μU/mL, FT3 1.9 ± 0.7 pg/mL, FT4 8.7 ± 3.6 pg/mL). Mean serum irisin concentrations significantly increased after 2 months under replacement therapy with levothyroxine (from 2.2 ± 0.6 to 2.9 ± 0.6 μg/mL, p < 0.0001). Variations of circulating levels of irisin under levothyroxine replacement therapy were directly correlated with those of FT3 (Rho = 0.454, p = 0.0033) and FT4 (Rho = 0.451, p = 0.0035). Multivariate regression analysis revealed that changes in thyroid hormones concentrations explained up to 10% of the variations of serum irisin levels under levothyroxine replacement therapy (FT3 R2 = 0.098, FT4 R2 = 0.103). Conclusion Our study suggests that levothyroxine replacement therapy mildly influences irisin metabolism in patients with recently onset hypothyroidism following total thyroidectomy.

Homocysteine, pituitary and thyroid hormones in children with different physical development levels after forest fires in the Chornobyl exclusion zone

2021 ◽  
pp. 11-18
Author(s):  
Yu.I. Bandazhevskyi ◽  
◽  
N. F. Dubova ◽  
Keyword(s):  
Thyroid Hormones ◽  
Forest Fires ◽  
Physical Development ◽  
Blood Levels ◽  
Exclusion Zone ◽  
Peripheral Tissues ◽  
Before And After ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Development Levels

Objective We performed a comparative assessment of the blood levels of homocysteine, pituitary and thyroid hormones in children with different levels of physical development before and after forest fires in the Chornobyl exclusion zone (ChEZ) in 2015. Methods: We used immunochemical, instrumental, mathematical and statistical methods. Results: The analysis of variable dynamics was performed in 336 adolescents of the Polisskyi and the Ivankivskyi districts of Kyiv region. An association was found between homocysteine (Нсу), hormones of the pituitary-thyroid axis and physical development of children. A statistically significantly higher level of Нсу was observed in the adolescents from the Ivankivskyi district in comparison with the children from the Polisskyi district. Forest fires in the spring and summer of 2015 in the ChEZ should be considered the main cause for the increase in Нсу in the blood of the adolescents. The increased level of Т3 in the peripheral tissues induced by Нсy and TSH contributed to a decrease in the physical development index values. Due to a decrease in the intensity of the Т4 deiodination process, the insufficient formation of Т3 in the peripheral tissues was recorded in the group of children with a disharmonious high physical development.

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