scholarly journals Effects of thyroid hormones on thermogenesis and energy partitioning

2018 ◽  
Vol 60 (3) ◽  
pp. R157-R170 ◽  
Author(s):  
K Alexander Iwen ◽  
Rebecca Oelkrug ◽  
Georg Brabant
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Cold Exposure ◽  
Energy Homeostasis ◽  
Current Knowledge ◽  
Hormone Replacement ◽  
Primary Hypothyroidism ◽  
The Central Nervous System ◽  
Primary Hyperthyroidism ◽  
Peripheral Cells

Thyroid hormones (TH) are of central importance for thermogenesis, energy homeostasis and metabolism. Here, we will discuss these aspects by focussing on the physiological aspects of TH-dependent regulation in response to cold exposure and fasting, which will be compared to alterations in primary hyperthyroidism and hypothyroidism. In particular, we will summarise current knowledge on regional thyroid hormone status in the central nervous system (CNS) and in peripheral cells. In contrast to hyperthyroidism and hypothyroidism, where parallel changes are observed, local alterations in the CNS differ to peripheral compartments when induced by cold exposure or fasting. Cold exposure is associated with low hypothalamic TH concentrations but increased TH levels in the periphery. Fasting results in a reversed TH pattern. Primary hypothyroidism and hyperthyroidism disrupt these fine-tuned adaptive mechanisms and both, the hypothalamus and the periphery, will have the same TH status. These important mechanisms need to be considered when discussing thyroid hormone replacement and other therapeutical interventions to modulate TH status.

Twice-Weekly Dosing for Thyroxine Replacement in Elderly Patients with Primary Hypothyroidism

1994 ◽  
Vol 22 (5) ◽  
pp. 273-277 ◽  
Author(s):  
J Taylor ◽  
B O Williams ◽  
J Frater ◽  
D J Stott ◽  
J Connell
Keyword(s):  
Thyroid Hormone ◽  
Elderly Patients ◽  
Hormone Replacement ◽  
Systolic Time Intervals ◽  
Serum Levels ◽  
Primary Hypothyroidism ◽  
Time Intervals ◽  
Thyroxine Therapy ◽  
Total Triiodothyronine ◽  
Systolic Time

Seven female patients (mean age 86 years) with proven biochemical primary hypothyroidism were enrolled in a single-blind randomized crossover study, of standard daily versus twice-weekly thyroxine therapy, with each phase of one month's duration. The median daily dose of thyroxine was 100 μg (range 75 – 100 μg). Serum levels of thyroid hormones and thyrotrophin were very similar during twice-weekly thyroxine therapy to those during daily therapy and there were no statistically significant differences between trough and peak serum total triiodothyronine, free thyroxine, or thyrotrophin levels or systolic time intervals during twice-weekly thyroxine. Administration of thyroxine twice-weekly to elderly patients with primary hypothyroidism gives effective biochemical thyroid hormone replacement, with no evidence from the systolic time intervals of tissue thyrotoxicosis at expected peak thyroid hormone concentrations. Supervised twice-weekly thyroxine should be considered in patients with primary hypothyroidism who comply poorly with daily dosing.

scholarly journals Effect of Adequate Thyroid Hormone Replacement on the Hypothalamo-Pituitary-Gonadal Axis in Premenopausal Women with Primary Hypothyroidism

2019 ◽  
Vol 8 (3) ◽  
pp. 152-158
Author(s):  
Bharath Bachimanchi ◽  
Suresh Vaikkakara ◽  
Alok Sachan ◽  
Ganji Praveen Kumar ◽  
Ashok Venkatanarasu ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Replacement ◽  
Premenopausal Women ◽  
Primary Hypothyroidism ◽  
Thyroid Hormone Replacement

scholarly journals Thyroid hyperactivity with high thyroglobulin in serum despite sufficient iodine intake in chronic cold adaptation in an Arctic Inuit hunter population

2012 ◽  
Vol 166 (3) ◽  
pp. 433-440 ◽  
Author(s):  
Stig Andersen ◽  
Kent Kleinschmidt ◽  
Bodil Hvingel ◽  
Peter Laurberg
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Cold Exposure ◽  
Cold Adaptation ◽  
Urinary Iodine ◽  
Thyroid Activity ◽  
East Greenland ◽  
Brown Adipose ◽  
Iodine Excretion ◽  
The Impact

ObjectiveAdult man hosts brown adipose tissue with the capacity to consume energy and dissipate heat. This is essential for non-shivering thermogenesis and its activation depends on sympathetic activity and thyroid hormones. This led us to evaluate the impact of chronic cold exposure on thyroid activity and thyroid hormones in serum in Arctic residents.DesignComparative, population-based study (n=535) performed in Greenland.MethodsHunters were compared with other men, and Inuit in remote settlements in East Greenland with no modern housing facilities were compared with the residents of the capital city in West Greenland and residents of a major town in East Greenland in a cross-sectional study. We used interview-based questionnaires, measured TSH, free thyroxine, free triiodothyronine (fT3), thyroglobulin (TG) antibody and TG (a measure of thyroid activity) in serum, and iodine and creatinine in spot urine samples.ResultsSerum TG was the highest among hunters (P=0.009) and settlement dwellers (P=0.001), who were most markedly exposed to cold, even though they had the highest urinary iodine excretion (hunters,P<0.001; settlement dwellers,P<0.001). Hunters and settlement dwellers also had the lowest fT3(hunters,P<0.001; settlement dwellers,P<0.001) after adjusting for gender, age, smoking habits, alcohol intake and iodine excretion in multivariate linear regression models. TSH was not influenced by measures of cold exposure (hunter,P=0.36; residence,P=0.91).ConclusionsCold exposure influenced thyroid hormones and TG in serum in Arctic populations consistent with consumption of thyroid hormone and higher thyroid hormone turnover. Findings emphasise that changes in thyroid activity are essential in cold adaptation in Arctic residents.

Manipulation of thyroid hormones in ruminants - a tool to understand their physiological role and identify their potential for increasing production efficiency

2002 ◽  
Vol 53 (3) ◽  
pp. 259 ◽  
Author(s):  
D. Villar ◽  
S. M. Rhind ◽  
J. R. Arthur ◽  
P. J. Goddard
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Production Efficiency ◽  
Hormone Replacement ◽  
Animal Health ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Physiological Role ◽  
Antithyroid Drugs ◽  
Few Data

Manipulations of thyroid hormone secretion and function can be used to cure thyroidal deficiencies or overactivity and as a tool to investigate their physiological roles and identify potential protocols for enhancing animal performance. An essential approach to the investigation of thyroid hormone action involves the induction of hypothyroidal states. Methods of inducing hypothyroidal states in ruminants include thyroidectomy and treatment with thionamides. There are few data concerning the induction of an optimal degree of hypothyroidism for the study of thyroid function in ruminants, unlike the situation in rodents. The effects of hypothyroidism on the physiology of ruminants, and the relative merits of thyroidectomy or of treatment with thionamides to manipulate thyroid hormone profiles in them, are reviewed and discussed. Thyroidectomy in ruminants induces an acute, irreversible, hypothyroidal state. It also has indirect, predominantly adverse, effects on many physiological processes and impairs health. Thus, thyroidectomised (THX) animals cannot be sustained for long-term studies without thyroid hormone replacement. Antithyroid drugs of the thionamide class, on the other hand, have been used with success to induce varying degrees of hypothyroidism, predominantly less severe than those induced by thyroidectomy. The changes induced by drugs are reversible upon withdrawal of treatment. However, treatment may require daily administration of the drug for several weeks before stable plasma concentrations of thyroid hormone are achieved. Furthermore, at high doses, these drugs can have toxic side effects. It is concluded that the treatment regime of choice will depend on the objectives of the individual study. Knowledge of the activities of thyroid hormone metabolising, deiodinase enzymes in the target tissues is also required if the actions of some of these drugs, their physiological roles in modulation of the thyroid hormones, and, crucially, their potential effects on animal health and production are to be properly understood and exploited.

Causes and laboratory investigation of hypothyroidism

2011 ◽  
pp. 530-537 ◽  
Author(s):  
Ferruccio Santini ◽  
Aldo Pinchera
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Hormones ◽  
Thyroid Hormone Receptor ◽  
Hormone Secretion ◽  
Thyroid Tissue ◽  
Clinical Manifestations ◽  
Primary Hypothyroidism ◽  
Central Hypothyroidism ◽  
Resistance To Thyroid Hormones

Hypothyroidism is the clinical state that develops as a result of the lack of action of thyroid hormones on target tissues (1). Hypothyroidism is usually due to impaired hormone secretion by the thyroid, resulting in reduced concentrations of serum thyroxine (T4) and triiodothyronine (T3). The term primary hypothyroidism is applied to define the thyroid failure deriving from inherited or acquired causes that act directly on the thyroid gland by reducing the amount of functioning thyroid tissue or by inhibiting thyroid hormone production. The term central hypothyroidism is used when pituitary or hypothalamic abnormalities result in an insufficient stimulation of an otherwise normal thyroid gland. Both primary and central hypothyroidism may be transient, depending on the nature and the extent of the causal agent. Hypothyroidism following a minor loss of thyroid tissue can be recovered by compensatory hyperplasia of the residual gland. Similarly, hypothyroidism subsides when an exogenous inhibitor of thyroid function is removed. Peripheral hypothyroidism may also arise as a consequence of tissue resistance to thyroid hormones due to a mutation in the thyroid hormone receptor. Resistance to thyroid hormones is a heterogeneous clinical entity with most patients appearing to be clinically euthyroid while some of them have symptoms of thyrotoxicosis and others display selected signs of hypothyroidism. The common feature is represented by pituitary resistance to thyroid hormones, leading to increased secretion of thyrotropin that in turn stimulates thyroid growth and function. The variability in clinical manifestations depends on the severity of the hormonal resistance, the relative degree of tissue hyposensitivity, and the coexistence of associated genetic defects (see Chapter 3.4.8).

scholarly journals Primary congenital hypothyroidism: defects in iodine pathways

2003 ◽  
pp. 247-256 ◽  
Author(s):  
JJ de Vijlder
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Congenital Hypothyroidism ◽  
Primary Hypothyroidism ◽  
Special Importance ◽  
Hormone Production ◽  
Central Hypothyroidism ◽  
Hormone Synthesis ◽  
Diagnosis And Classification ◽  
The Central Nervous System

The thyroid gland is the only source of thyroid hormone production. Thyroid hormone is essential for growth and development, and is of special importance for the development of the central nervous system. It was for that reason that neonatal screening on congenital hypothyroidism was introduced and is now performed in many countries. Defects in thyroid hormone production are caused by several disorders in hormone synthesis and in the development of the thyroid gland (primary hypothyroidism) or of the pituitary gland and hypothalamus (central hypothyroidism).This paper describes defects in the synthesis of thyroid hormone caused by disorders in the synthesis or iodination of thyroglobulin, leakage of iodinated proteins by a stimulated thyroid gland and the presence of abnormal iodoproteins, mainly iodinated albumin, in the thyroid gland and blood circulation. Circulating thyroglobulin and abnormal iodoproteins, as well as the breakdown products of these iodoproteins excreted in urine, are used for etiological diagnosis and classification. Moreover, our finding of an enzyme that catalyses the dehalogenation of iodotyrosines, which is important for iodine recycling and required for economical use of iodine, is also referred to.

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