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Post-Exercise Recovery Period
Published in Atko Viru, Adaptation in Sports Training, 2017
Immediately after a marathon run, increased thyroid activity was evidenced by elevated blood levels of free thyroxine, free triiodothyronine, and thyrotropin. Free thyroxine remained elevated 1 h later as well. At 22 h after the race the thyrotropin concentration was decreased, and thyroxine and triiodothyronine levels were close to pre-race values. Comparison of the changes of free thyroxine or free triiodothyronine to free reverse triiodothyronine indicated that 22 h after the race a favored conversion of active hormones to inactive reverse triiodothyronine still exists.126 After an 80-min exercise at 75% VO2max no changes in the free thyroxine levels were found.50
Information on level of drugs into breastmilk
Published in Wendy Jones, Breastfeeding and Medication, 2013
Bennett PN (ed.), Drugs and human lactation, Amsterdam: Elsevier, 1988. Oberkotter LV, Tenore A, Separation and radioimmunoassay of T3 and T4 in human breastmilk, Horm Res, 1983;17:11–18. Sato T, Suzuki Y, Presence of triiodothyronine, no detectable thyroxine and reverse triiodothyronine in human milk, Endocrinol Jpn, 1979;26:507–13.
Seasonal variations in levels of human thyroid-stimulating hormone and thyroid hormones: a meta-analysis
Published in Chronobiology International, 2021
N. V. Kuzmenko, V. A. Tsyrlin, M. G. Pliss, M. M. Galagudza
T4 has minimal physiological activity and can be further transformed by deiodinases DIO1 and DIO2 to active triiodothyronine (T3) and by DIO3 to inactive reverse triiodothyronine (rT3) (Arrojo et al. 2011; Dardente et al. 2014, 2010). Changes in DIO2 and DIO3 activity in tissues combined with the seasonal dynamics of TSH expression regulate the circannual-associated changes in metabolism and reproductive behavior of mammals (Arrojo et al. 2011; Dardente et al. 2014; Nakane and Yoshimura 2014). TSH stimulates DIO2 expression by binding to corresponding receptors in ependymal cells of the mediobasal hypothalamus (Dardente et al. 2014). For most mammalian species studied to date, a typical expression pattern of DIO isoforms is characteristic with high expression levels of DIO2 and low expression of DIO3 occurring during long days of sunlight and high expression levels of DIO3 and low expression of DIO2 occurring during short days of sunlight (Ebling 2014).
Thyroid disease in the perimenopause and postmenopause period
Published in Climacteric, 2018
M. M. Uygur, T. Yoldemir, D. G. Yavuz
Postmenopause is defined as a permanent cessation of menstruation for 12 months due to the loss of ovarian function. There is an increasing prevalence of thyroid disorders with aging, particularly higher in postmenopausal women. The diagnosis is challenging in these patients due to symptoms like weight gain, dependent decline in free triiodothyronine (FT3) levels, and increase in reverse triiodothyronine (T3) levels. Sweating, insomnia, and palpitations can be attributed to both ovarian and thyroid dysfunction. The interpretation of thyroid function due to aging, other comorbidities, and use of multiple pharmaceuticals among these age groups makes decision-making more difficult.
Effect of chemoradiation on the size of the thyroid gland
Published in Baylor University Medical Center Proceedings, 2020
Ana Marcella Rivas, Eneko Larumbe-Zabala, Olaia Diaz-Trastoy, Ryan Nicholas Schurr, Catherine Jones, Ramzi Abdulrahman, Nabeel Dar, Joaquin Lado-Abeal
In our sample, the thyroid gland received a median radiation dose of 1.265 Gy due to scattering. However, we did not find a correlation between the radiation received by the thyroid gland and the reduction in thyroid gland volume. Although a lack of statistical power due to the small size of our sample could explain the lack of correlation, it is possible that other factors might be driving the reduction of the thyroid gland volume. Chemotherapy agents are well known to affect the size and function of the thyroid gland,12 but data on taxanes, alkylating agents, and topoisomerase II inhibitors are scarce. Doxorubicin has cytotoxic effects by triggering Fas-mediated apoptosis in thyroid cancer cell lines15; however, only two of our patients received this agent. A study in mice and guinea pigs found a significant and prolonged decrease in serum thyroxine (T4), increase in reverse triiodothyronine (rT3), and no change in triiodothyronine (T3) levels after acute and chronic administration of cyclophosphamide.16 Similarly, a study looking at the effect of cyclophosphamide and ifosfamide administration on thyroid function found an increase in serum T4 and rT3 and a drop in thyroid-stimulating hormone (TSH), with no changes in T3, thyroglobulin, or thyroid-binding globulin, suggesting that alkylating agents might induce the release of thyroid hormone from cellular pools outside the thyroid, such as the liver.17 These effects are transient, with a normalization of the levels 2 days after drug administration. Finally, thyroid function tests obtained in 21 patients before and after six cycles of docetaxel, doxorubicin, and cyclophosphamide for breast cancer showed a significant decrease in serum free T4 and increase in TSH. The authors hypothesized that these changes may result from damage to the thyroid cell inflicted by chemotherapy or that lower levels of free T4 during chemotherapy represent an adaptive response to protect against tissue damage by down-regulating cellular metabolism.13