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Hypothyroidism
Published in Charles Theisler, Adjuvant Medical Care, 2023
Hypothyroidism, also called underactive thyroid or low thyroid, is a disorder of the endocrine system in which the thyroid gland is unable to produce adequate amounts of thyroid hormone. Primary hypothyroidism (due to thyroid gland destruction) accounts for >90% of cases. The most common cause is an autoimmune disorder known as Hashimoto’s thyroiditis, but other causes include thyroidectomy, radioactive iodine treatment, and radiation. Also, medications such as amiodarone and lithium may also lead to an underactive thyroid.
Influence of medication on typical exercise response
Published in R. C. Richard Davison, Paul M. Smith, James Hopker, Michael J. Price, Florentina Hettinga, Garry Tew, Lindsay Bottoms, Sport and Exercise Physiology Testing Guidelines: Volume II – Exercise and Clinical Testing, 2022
Up to 1 in 6 women over 50 have an underactive thyroid and approximately 2% of the entire population take medication to replace their thyroid levels. Levothyroxine is the most commonly prescribed medication for this purpose. Levothyroxine is a synthetic pre-hormone, usually taken in tablet form and mostly absorbed in the jejunum. Levothyroxine absorption is extremely sensitive to a number of factors including dietary fibre, fasting, age and exercise. Once absorbed, it is converted by the body into T4 (the main thyroid hormone) in the liver and undergoes enterohepatic circulation (KGaA, 2013).
Selected topics
Published in Henry J. Woodford, Essential Geriatrics, 2022
Thermoregulation becomes impaired as a consequence of frailty. Dysfunction of multiple physiological systems can contribute to this. Average core body temperature is estimated to be 0.4°C lower in older people compared to younger people.55 Core bodily temperature is a balance between heat creation from metabolism and heat loss from the skin, including evaporation of sweat. Blood flow to the skin is a key process in thermoregulation. The abilities to vasodilate and vasoconstrict are impaired in older people, making them more susceptible to hypothermia in cold conditions and overheating in hot settings. This is probably mediated by a reduction in sympathetic nervous system activity. Sweat production can be reduced when blood flow to the skin is impaired or with dehydration. Heat production is proportional to muscle mass, which declines with sarcopenia. Reduced activity can also result in less heat generation. There may be a reduced shivering response to hypothermia. Insulating fat conserves heat. There is a reduction in the subcutaneous fat layer in old age. Brown adipose tissue is important for thermogenesis in new-borns but probably not in adults. An underactive thyroid gland is a possible additional factor. Peripheral thermosensor receptors and central brain processing can be impaired in older age. There may also be cognitive aspects, such as wearing the appropriate clothing and home heating. Figure 22.1 summarises the aspects that promote hypothermia in frail older people. Paradoxical undressing can occur with hypothermia.56
Sex-specific characteristics for the coexistence of asthma and COPD in the Canadian population: a cross-sectional analysis of CLSA data
Published in Journal of Asthma, 2023
Edwina Veerasingam, Zhiwei Gao, Jeremy Beach, Ambikaipakan Senthilselvan
In this study, the proportion of comorbidities in the asthma + COPD group was similar to that observed in the COPD-only group and was greater than those observed in control and asthma-only groups among both females and males. The proportion of osteoporosis was significantly greater in the asthma + COPD, COPD-only and asthma-only groups than in the control group. These finding were also reported in other studies (6,10). This association may be related to the potential confounding effect of vitamin D which has been shown to be associated with osteoporosis, asthma and COPD (35,36). In addition, systemic inflammation and glucocorticoid use have been reported to be risk factors of osteoporosis in subject with COPD (37) and long-term use of systemic glucocorticoids has been shown to be associated with osteoporosis in subjects with severe asthma (38). In this study, females had a significantly greater proportion of underactive thyroid disease than males in all the outcome groups. In a Turkish study, underactive thyroid disease was more frequent than overactive thyroid disease among subjects with COPD (39). In a large population-based study of adults aged 40 years and above from Spain, the proportion of thyroid disease and osteoporosis was greater in females than men among subjects with COPD (40). In a review article, osteoporosis has been reported to be more prevalent in females than males among subjects with COPD (41).
Using the Biopsychosocial Approach to Identify Factors Associated with Major Depressive Disorder for Individuals with Hypothyroidism
Published in Issues in Mental Health Nursing, 2022
Kennedy S. Anderson, Krista J. Howard, Kelly B. Haskard-Zolnierek, Julia Pruin, Rebecca G. Deason
Hypothyroidism, or underactive thyroid, is described as a deficiency of thyroid hormones (American Thyroid Association, 2020). A diagnosis of hypothyroidism is made following a blood test to assess the function of thyroid stimulating hormone (TSH), and treatment typically consists of the thyroid hormone supplement thyroxine (T4) while some patients also are given the additional triiodothyronine (T3) supplement. Common physical symptoms of hypothyroidism include lethargy, sensitivity to cold, constipation, dry skin, weight gain, sexual dysfunction, and neck swelling (Ali et al., 2017; El Saide Sayyah et al., 2013). Hypothyroidism has also been implicated in changes in mood and cognition, such as poorer attention, memory, and executive function and increased rates of anxiety and depression (Samuels, 2014).
A new formulation of levothyroxine engineered to meet new specification standards
Published in Current Medical Research and Opinion, 2019
Hans-Peter Lipp, Ulrike Hostalek
Thyroid disorders are common among patients managed in the primary care setting, and hormone replacement therapy with levothyroxine (T4) is the mainstay of management for people with an underactive thyroid (hypothyroidism)1,2. Indeed, levothyroxine has been the most-prescribed drug in the US in recent years3. Regulatory standards for the manufacturers regarding the specification of levothyroxine preparations have become more stringent in recent years4–6 (described below), and some existing preparations needed a reformulation as a consequence. Here, we describe a new formulation of a widely used levothyroxine preparation, Euthyrox* New Formulation (NF), developed to meet these tightened requirements. A summary of the development and properties of the new formulation is followed by a summary of practical information relevant to its therapeutic use.