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11/7/23, 1:57 PM Realizeit for Student Hypothyroidism Hypothyroidism results from suboptimal levels of thyroid hormone. Thyroid deficiency can affect all body functions and can range from mild, subclinical forms to myxedema (severe deficiency discussed later), an advanced life-threatening form. Th...

11/7/23, 1:57 PM Realizeit for Student Hypothyroidism Hypothyroidism results from suboptimal levels of thyroid hormone. Thyroid deficiency can affect all body functions and can range from mild, subclinical forms to myxedema (severe deficiency discussed later), an advanced life-threatening form. The most common cause of hypothyroidism in adults is autoimmune thyroiditis (Hashimoto disease), in which the immune system attacks the thyroid gland. Symptoms of hyperthyroidism may later be followed by those of hypothyroidism and myxedema. Hypothyroidism also commonly occurs in patients with previous hyperthyroidism that has been treated with radioiodine or antithyroid medications or thyroidectomy (surgical removal of all or part of the thyroid gland). Testing of thyroid function is recommended for all patients who receive radiation therapy to the neck. More than 95% of patients with hypothyroidism have primary or thyroidal hypothyroidism, which refers to dysfunction of the thyroid gland itself. If the cause of the thyroid dysfunction is failure of the pituitary gland, the hypothalamus, or both, the hypothyroidism is known as central hypothyroidism. If the cause is entirely a pituitary disorder, it may be referred to as pituitary or secondary hypothyroidism. If the cause is a disorder of the hypothalamus resulting in inadequate secretion of TSH due to decreased stimulation of TRH, it is referred to as hypothalamic or tertiary hypothyroidism. If thyroid deficiency is present at birth, it is referred to as neonatal hypothyroidism. In such instances, the mother may also have thyroid deficiency. The term myxedema refers to the accumulation of mucopolysaccharides in subcutaneous and other interstitial tissues. Although myxedema occurs in long-standing hypothyroidism, the term is used appropriately only to describe the extreme symptoms of severe hypothyroidism (Chaker, Bianco, Janklaas, et al., 2017). Clinical Manifestations Presenting clinical manifestations in adults frequently reflect the decrease in metabolism resulting from the decrease in thyroid function. Clinical manifestations include complaints of fatigue and lethargy that may interfere with activities of daily living, weight gain without an increased intake of calories, cold intolerance, dry skin, and, in some patients, a deepening of the voice. Other clinical manifestations are related to gender, age, and duration of the decrease in thyroid function. These include cardiovascular-related manifestations such as bradycardia and changes in electrical conduction of the heart which will be noted on the electrocardiogram (ECG). In women, changes in the menstrual cycle will be noted (Chaker et al., 2017). Severe hypothyroidism results in a subnormal body temperature and pulse rate. The patient usually begins to gain weight even without an increase in food intake, although they may be cachectic. The skin becomes thickened because of an accumulation of mucopolysaccharides in the subcutaneous https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZMyySaAjt8dTx3FnIrt15HOKniKu5nqplgCFS7%2bEIEJ2a… 1/2 11/7/23, 1:57 PM Realizeit for Student tissues. The hair thins and falls out, and the face becomes expressionless and masklike. The patient often complains of being cold even in a warm environment. At first, the patient may be irritable and may complain of fatigue, but as the condition progresses, the emotional responses are subdued. The mental processes become dulled, and the patient appears apathetic. Speech is slow, the tongue enlarges, the hands and feet increase in size, and deafness may occur. The patient frequently reports constipation. Advanced hypothyroidism may produce personality and cognitive changes characteristic of dementia. Inadequate ventilation and sleep apnea can occur with severe hypothyroidism. Pleural effusion, pericardial effusion, and respiratory muscle weakness may also occur (Chaker et al., 2017). Severe hypothyroidism is associated with an elevated serum cholesterol level, atherosclerosis, coronary artery disease, and poor left ventricular function. The patient with advanced hypothyroidism is hypothermic and abnormally sensitive to sedative, opioid, and anesthetic agents, which must be given with extreme caution. Patients with unrecognized hypothyroidism who are undergoing surgery are at increased risk for intraoperative hypotension, postoperative heart failure, and altered mental status. Myxedema coma is a rare life-threatening condition and a decompensated state of severe hypothyroidism in which the patient is hypothermic and unconscious. This condition may develop with undiagnosed hypothyroidism and may be precipitated by infection or other systemic disease or by use of sedatives or opioid analgesic agents. Patients may also experience myxedema coma if they forget to take their thyroid replacement medication. The condition occurs most often among older women in the winter months and appears to be precipitated by cold. However, the disorder can affect any age group. In myxedema coma, the patient may initially show signs of depression, diminished cognitive status, lethargy, and somnolence (Chaker et al., 2017). Increasing lethargy may progress to stupor. The patient’s respiratory drive is depressed, resulting in alveolar hypoventilation, progressive carbon dioxide retention, narcosis, and coma. In addition, patients with myxedema coma can also exhibit hyponatremia, hypoglycemia, hypoventilation, hypotension, bradycardia, and hypothermia. These symptoms, along with cardiovascular collapse and shock, require aggressive and intensive supportive and hemodynamic therapy if the patient is to survive. Although there has been a decline in mortality rates over the past two decades due to early intervention and improved therapies, the mortality rate remains at 40% despite treatment; proper diagnosis and prompt treatment is essential (Eledrisi, 2018). https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZMyySaAjt8dTx3FnIrt15HOKniKu5nqplgCFS7%2bEIEJ2a… 2/2