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Endocrine Disorders, Contraception, and Hormone Therapy during Pregnancy
Published in “Bert” Bertis Britt Little, Drugs and Pregnancy, 2022
L-Thyroxine (T4) is a hormone normally produced in the thyroid gland. It is used to treat thyroid deficiency and is suitable for use during pregnancy. The frequency of congenital anomalies was not increased among 537 pregnancies exposed to exogenous thyroxine or thyroid hormone during the first trimester, and 1,605 pregnancies exposed at any time during pregnancy (Heinonen et al., 1977a). In another uncontrolled study of 554 infants whose mothers were exposed in the first trimester, the frequency of major anomalies was 4.5 percent, which is not different from background (Briggs et al., 2021).
Miscellaneous Tips
Published in John Larkin, 101 Top Tips in Medicine, 2021
Note, this is for patients on thyroxine already. Not those not on thyroxine who insist they must have hypothyroidism despite the absolutely normal tests and lack of clinical signs because it says in Red Mariepolitan magazine that …
The patient with acute endocrine problems
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Effects of thyroxine include:Stimulates basal metabolic rate, resulting in increased oxygen consumption and heat production (thermogenesis).CNS and cardiovascular sensitivity to catecholamines, e.g., increased heart rate and contractility.Enzyme synthesis, which promotes protein, fat and carbohydrate metabolism.Growth and development, e.g., of the nervous system.
Toward a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny – part I: which parameters from human studies are most relevant for toxicological assessments?
Published in Critical Reviews in Toxicology, 2020
Ursula G. Sauer, Alex Asiimwe, Philip A. Botham, Alex Charlton, Nina Hallmark, Sylvia Jacobi, Sue Marty, Stephanie Melching-Kollmuss, Joana A. Palha, Volker Strauss, Bennard van Ravenzwaay, Gerard Swaen
The thyroid gland is an endocrine organ present in all vertebrates. Thyroxine (T4) is the main thyroid hormone synthesised and secreted by the thyroid, whereas triiodothyronine (T3), the biologically active hormone, is mostly produced by deiodination of T4 in peripheral tissues. A major role of the thyroid hormones is to regulate metabolism, e.g. during growth and reproduction. In developing offspring, rodent data (with supporting evidence in humans) indicate that thyroid hormones play a role in neuronal migration, cellular differentiation (e.g. of neurons) and glial myelination. The thyroid gland is controlled by the pituitary [through secretion of thyroid stimulating hormone (TSH)] which, in turn, is regulated by the thyrotropin releasing hormone secreted by the hypothalamus (Dickhoff and Darling 1983; DeGroot and Jameson 2001). Thyroid hormones are highly hydrophobic and therefore generally bound to serum binding proteins when circulating in the bloodstream, whereas only a minor fraction (<1%) remains as free hormones (e.g. free T4 (fT4) and free T3). It is the free hormone fraction that is sensed by the tissues, triggering the homeostatic regulatory mechanisms (Stockigt 2001).
Integrating oral semaglutide into clinical practice in primary care: for whom, when, and how?
Published in Postgraduate Medicine, 2020
Stephen A. Brunton, Ofri Mosenzon, Eugene E. Wright Jr
When oral semaglutide is administered concomitantly with medications that have narrow therapeutic windows or that require clinical monitoring, increased clinical/laboratory monitoring should be considered [9]. An example of such an agent is levothyroxine, which is used as a thyroid hormone replacement therapy and is recommended to be taken on an empty stomach before breakfast [81]. When a single dose of levothyroxine 600 µg was co-administered with oral semaglutide at steady-state in a study in healthy volunteers, thyroxine exposure increased by 33%, potentially due to a delay in gastric emptying caused by oral semaglutide [9,73]. Patients taking concomitant levothyroxine should therefore be advised to comply with the dosing conditions for oral semaglutide [9]. In line with current medical guidance, close monitoring of thyroxine parameters should be considered and patients could consider taking levothyroxine at least 3 hours after the last meal of the day instead of in the morning [73,74].
Panax ginseng root, not leaf, can enhance thermogenic capacity and mitochondrial function in mice
Published in Pharmaceutical Biology, 2020
Su-hui Wu, Han-bing Li, Gen-Lin Li, Yue-juan Qi, Juan Zhang, Bai-yan Wang
Thyroid hormones (TH), which are secreted by the thyroid gland, are known to increase metabolism and are the well-established principal endocrine regulators of both obligatory and facultative thermogenesis in human and animals (Goglia et al. 2002; Psarra et al. 2006; Cioffi et al. 2013; Solmonson and Mills 2016). It has been suggested that thyroxine (T4) supplementation can increase resting metabolism (Johannsen et al. 2012). Thyroid hormones increase BAT thermogenesis after T4 is converted to T3 in rodents (Broeders et al. 2016). Consequently, it has been thought that thyroid hormones are molecular determinants of thermogenesis (Silvestri et al. 2005). Because of this, there is a possible connection between thyroid hormones and BAT activity in cold circumstances, which potentially occur through mitochondria (Cioffi et al. 2013). Mitochondria, which have been and continue to be the target of most studies on the calorigenic effects of TH, provide nearly 90% of energy supply in cells (Cioffi et al. 2013).