Thyroid Hormone Economy in Response to Extreme Cold Exposure in Healthy Factory Workers*

Solter, Miljenko; Brkić, Kornelije; Petek, Marijan; Posavec, Ljubica; Sekso, M

doi:10.1210/jcem-68-1-168

Cited by 22 publications

(15 citation statements)

References 17 publications

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“…The influence of cold exposure on circulating thyroid hormone concentrations has been studied using a variety of study set-ups (24,25,26,27,28,29,36,37,38,39,40). A slight decrease in thyroid hormone concentrations in serum (26,27) has been observed.…”

Section: Discussionmentioning

confidence: 99%

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

Andersen

Kleinschmidt²,

Hvingel³

et al. 2012

European Journal of Endocrinology

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Objective: Adult 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. Design: Comparative, population-based study (nZ535) performed in Greenland. Methods: Hunters 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 (fT 3 ), thyroglobulin (TG) antibody and TG (a measure of thyroid activity) in serum, and iodine and creatinine in spot urine samples. Results: Serum TG was the highest among hunters (PZ0.009) and settlement dwellers (PZ0.001), 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 fT 3 (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, PZ0.36; residence, PZ0.91). Conclusions: Cold 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.

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Section: Discussionmentioning

confidence: 99%

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

Andersen

Kleinschmidt²,

Hvingel³

et al. 2012

European Journal of Endocrinology

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“…Catecholamines, which are thought to play an important role in response to cold and interact with T % during cold adaptation [35][36][37], might increase iodothyronine 5h-deiodinase activity [38]. Solter et al [33] explained that the increased serum free thyroid hormone levels imply a higher equilibrium between extracellular and intracellular FT % and FT $ as a result of prolonged intermittent cold exposure.…”

Section: Discussionmentioning

confidence: 99%

Central cooling effects in patients with hypercholesterolaemia

Lorenzo¹,

Mukherjee²,

Kadziola³

et al. 1998

Clinical Science

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1. A prospective study has been carried out, and 68 patients with hypercholesterolaemia have been investigated to study the effects of central cooling on serum lipid levels. 2. Central cooling was obtained by the exposure of the whole body to cold water. All patients were trained to gradually reduce the water temperature from 22 to 14 degrees C and to increase the time of exposure from 5 to 20 min over a period of 90 days. The 33 male and 35 female patients were aged between 40 and 60 years at entry with total cholesterol of 6.0 mmol/l or greater and low-density lipoprotein (LDL)-cholesterol of 4. 0 mmol/l or greater. Thyroid-stimulating hormone, free thyroxine (FT4), total T3, total cholesterol, LDL-cholesterol, high-density lipoprotein (HDL)-cholesterol, triacylglycerols and total fat mass (determined by dual-energy X-ray absorptiometry scan) were obtained at baseline and after 3 months treatment with hydrotherapy. 3. Central cooling obtained by hydrotherapy results in a median fall in tympanic temperature from 0.2 degrees C (P<0.001) to 0.8 degrees C (P<0.001). We have observed in these patients a significant reduction in total cholesterol (-0.2 mmol/l, P=0.006) and LDL-cholesterol (-0.2 mmol/l, P=0.004). Serum FT4 level was higher than baseline results in 30 of these hypercholesterolaemic patients (15.5 pmol/l to 17.3 pmol/l) and there was no significant change in serum thyroid-stimulating hormone and total T3. 4. In conclusion, in our patients with hypercholesterolaemia we have observed a significant reduction of total cholesterol and LDL-cholesterol after body temperature regulation.

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“…There are cases of humans with partial or total TBG deficiency, which results in euthyroid hypothyroxinemia (Refetoff 1989, Bartalena 1993. Even though exposure to cold is known to induce alteration in thyroid hormone metabolism in humans (Solter et al 1989, Sawhney et al 1995, Do et al 2004, to the best of our knowledge there are no reports on the ability of these individuals to adapt to cold. Because TTR-null mice are also euthyroid hypothyroxinemic, it is reasonable to believe that humans with TBG deficiency would normally adapt to cold.…”

Section: Figurementioning

confidence: 99%

Transthyretin is not necessary for thyroid hormone metabolism in conditions of increased hormone demand

Sousa¹,

Escobar²,

Oliveira³

et al. 2005

Journal of Endocrinology

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Thyroid hormones circulate in blood mainly bound to plasma proteins. Transthyretin is the major thyroxine plasma carrier in mice. Studies in transthyretin-null mice revealed that the absence of transthyretin results in euthyroid hypothyroxinemia and normal thyroid hormone tissue distribution, with the exception of the choroid plexus in the brain. Therefore, transthyretin does not influence normal thyroid hormone homeostasis under standard laboratory conditions. To investigate if transthyretin has a buffer/storage role we challenged transthyretin-null and wild-type mice with conditions of increased hormone demand: (i) exposure to cold, which elicits thermogenesis, a process that requires thyroid hormones; and (ii) thyroidectomy, which abolishes thyroid hormone synthesis and secretion and induces severe hypothyroidism. Transthyretin-null mice responded as the wild-type both to changes induced by stressful events, namely in body weight, food intake and thyroid hormone tissue content, and in the mRNA levels of genes whose expression is altered in such conditions. These results clearly exclude a role for transthyretin in thyroid hormone homeostasis even under conditions of increased hormone demand.

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Thyroid Hormone Economy in Response to Extreme Cold Exposure in Healthy Factory Workers*

Cited by 22 publications

References 17 publications

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

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

Central cooling effects in patients with hypercholesterolaemia

Transthyretin is not necessary for thyroid hormone metabolism in conditions of increased hormone demand

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