Hypothyroidism Myxedema

Thyroid Disease. Hypothyroidism (myxedema) [169] and hyperthyroidism [170] alter small bowel motility. Although today these diseases are usually recognized before such symptoms develop, thyroid function must be examined in unexplained intestinal pseudoobstruction. 

Hypothyroidism (myxedema) results when there is a breakdown of thyroid hormone production in the thyroid gland. Treatment consists of replacing this hormone with aforementioned drugs. Treatment with levothyroxine, 3,5,3, 5 -tetraiodothyronine, is preferred. Lyothyronin, L-3,5,5 -triiodothyronine, is also used, as is lotrix, a mixture of levothyroxine and levothyronine in a 4 1 ratio. Of the drugs of animal origin, thyroidin and thy-roglobulin (proloid) are used. 

Patients with adrenal insufficiency (Addison s disease) and those with hypothyroidism (myxedema) may have prolonged and exaggerated responses to opioids. 

There are many forms of hypothyroidism, differing in their cause and age of onset (see Table 31-1). Severe adult hypothyroidism (myxedema) may occur idio-pathically or may be caused by specific factors such as autoimmune lymphocytic destruction (Hashimoto disease). In the child, thyroid function may be congenitally impaired, and cretinism will result if this condition is untreated. Hypothyroidism may result at any age if the dietary intake of iodine is extremely low. Several other forms of hypothyroidism that have a genetic or familial basis also exist.54... 

Thyroid extract is used in the treatment of hypothyroidism, myxedema, and cretinism. It is also used as a diagnostic agent and for suppression of pituitary thyroid-stimulating hormone. Synthetic derivatives are preferred because of uniform potency. 

Effects of thyroid hormone The organ level actions of the thyroid drugs include normal growth and development of the nervous, skeletal, and reproductive systems and control of metabolism of fats, carbohydrates, proteins, and vitamins. The results of excess thyroid activity (thyrotoxicosis) and hypothyroidism (myxedema) are summarized in Table 38-1. 

Endemic cretinism (neurologic cretinism) Congenital hypothyroidism Myxedema (adult hypothyroidism)... 

Myxedema and goiter are the main conditions for which thyroid preparations are indicated. The treatment of cretinism is difficult because it is recognized only at or after birth. Even if this disease could be diagnosed m utero, thyroid hormones do not readily cross the placental barrier. In addition, the fetus, as does a premature infant, rapidly deactivates the thyroid hormones. The halogen-free analogue DlMlT [26384-44-7] (3), which is resistant to fetal deiodinases, may prove useful for fetal hypothyroidism (cretinism). 

Myxedema is a severe hypothyroidism manifested by lethargy, apathy, memory impairment, emotional changes, slow speech, deep coarse voice, thick dry skin, cold intolerance, slow pulse, constipation, weight gain, and absence of menses. 

Hypothyroidism can affect virtually any tissue or organ in the body. However, the most common symptoms, such as fatigue, lethargy, sleepiness, cold intolerance, and dry skin, are nonspecific and are seen with many other disorders. The classic overt signs, such as myxedema and delayed deep tendon reflexes, are seen uncommonly now because more patients are... 

Myxedema coma is seen in advanced hypothyroidism. These patients develop CNS depression, respiratory depression, cardiovascular instability, and fluid and electrolyte disturbances. Myxedema coma often is triggered by an underlying acute medical condition such as infection, stroke, trauma, or administration of CNS depressant drugs. 

Myxedema Advanced hypothyroidism characterized by a relatively firm edema of subcutaneous tissue, subnormal body temperature, dryness and loss of hair, hoarseness, and muscle weakness. 

The following factors have been suggested as alternatives to consider when presented with a potential case of exposure to carbon monoxide diabetic ketoacidosis, hypothyroidism and myxedema coma, labyrinthitis, and lactic acidosis toxic exposures resulting in methemoglobinemia ingestion of alcohols or narcotics and diseases that cause gastroenteritis, encephalitis, meningitis, and acute respiratory distress syndrome. 

Myxedema coma is a rare consequence of decompensated hypothyroidism manifested by hypothermia, advanced stages of hypothyroid symptoms, and altered sensorium ranging from delirium to coma. Untreated disease is associated with a high mortality rate. 

This disease is characterized by a decrease or lack of endogenic thyroid hormone secretion. When originating in childhood, it can be clinically described as cretinism (infantile hypothyroidism), and in adults as myxedema (adult hypothyroidism), which is expressed in a loss of mental or physical ability to work, suppression of metabolic processes in the body, and edema. Since thyroid function cannot be restored, the clinical effect is only visible when using thyroid hormones. Using thyroid hormones in hypothyroidism is a replacement therapy that does not correct the disease itself. 

Use with caution in the foiiowing Elderly or debilitated severe impairment of hepatic, pulmonary or renal function myxedema or hypothyroidism adrenal cortical insufficiency CNS depression or coma toxic psychoses prostatic hypertrophy or urethral stricture acute alcoholism delirium tremens or kyphoscoliosis. Naloxone may not be effective in reversing respiratory depression. 

In adults, the signs and symptoms of hypothyroidism include somnolence, slow mentation, dryness and loss of hair, increased fluid in body cavities (e.g., the pericardial sac), low metabolic rate, tendency to gain weight, hyperlipidemia, subnormal temperature, cold intolerance, bradycardia, reduced systolic and increased diastolic pulse pressure, hoarseness, muscle weakness, slow return of muscle to the neutral position after a tendon jerk, constipation, menstrual abnormalities, infertility, and sometimes myxedema (hard edema of subcutaneous tissue with increased content of proteoglycans in the fluid). A goiter (i.e., enlargement of the thyroid gland) may be present. 

The most extreme manifestation of untreated hypothyroidism is myxedema coma, which even if detected early and appropriately treated, carries a mortality rate of 30 to 60%. Myxedema coma is a misnomer. Most patients exhibit neither the myxedema nor coma. Patients with myxedema coma usually have longstanding hypothyroidism with the classic symptoms of hypothyroidism. Decompensation into myxedema coma may occur when the homeostatic mechanisms of the severely hypothyroid patient are subject to a stressful precipitating event (e.g., infection, trauma, some medications, stroke, surgery). The principal manifestation of myxedema coma is a deterioration of mental status (apathy, confusion, psychosis, but rarely coma). Other common clinical features include hypothermia, diastolic hypertension (early), hypotension (late), hypoventilation, hypoglycemia, and hyponatremia. If myxedema coma is suspected, the patient is usually admitted to an intensive care unit for pulmonary and cardiovascular support... 

Hypothyroidism PO Initially, 15-30 mg. May increase by 15-mg increments q2-4wk. Maintenance 60-120 mcg/day. Use 15 mg in patients with cardiovascular disease or myxedema. 

Thyroid deficiency (hypothroidism) has been connected to cretinism and myxedema. Cretinism occurs when hypothyroid children are born intellectually handicapped, are small, and have coarse hair and thick skin. Myxedema, seen in older hypothyroid people, is characterized by subcutaneous semifluid deposits, causing puffiness of the hands and face. The basal metabolism of these patients is depressed to 30 0% below normal, and their body temperature and pulse rate are also reduced. Women suffering from hypothyroidism may give birth to children afflicted with cretinism. 

Thyroxine is absorbed best in the duodenum and ileum absorption is modified by intraluminal factors such as food, drugs, gastric acidity, and intestinal flora. Oral bioavailability of current preparations of L-thyroxine averages 80% (Table 38-1). In contrast, T3 is almost completely absorbed (95%). T4 and T3 absorption appears not to be affected by mild hypothyroidism but may be impaired in severe myxedema with ileus. These factors are important in switching from oral to parenteral therapy. For parenteral use, the intravenous route is preferred for both hormones. 

Myxedema coma is an end state of untreated hypothyroidism. It is associated with progressive weakness, stupor, hypothermia, hypoventilation, hypoglycemia, hyponatremia, water intoxication, shock, and death. 

Neonatal goiter caused by the use of potassium iodine as an expectorant during pregnancy has been reported (67). The neonate, a girl, had acute hypothyroidism, with myxedema and respiratory distress. She was given levothyroxine for 6 months, with complete normalization of thyroid function. 

Myxedema The adult or acquired form of hypothyroidism characterized by decreased metabolic rate, lethargy, decreased mental alertness, weight gain, and other somatic changes. 

Hypothyroidism, known as myxedema in adults, when severe, is the most common disorder of the thyroid gland. Worldwide, hypothyroidism is most often the result of endemic iodine deficiency. In nonendemic areas, where iodine is sufficient in the diet, chronic autoimmune thyroiditis (Hashimoto s thyroiditis) accounts for the majority of cases. This disorder is primarily characterized by high levels of circulating antibodies against a key enzyme (thyroid peroxidase) in the processing of iodine in the thyroid gland. Blocking antibodies directed at the TSH receptor may also be present. Thyroid destruction may also occur via apoptotic cell death. 

Thyroid disorders may be divided into over- and underproduction of the thyroid hormones. These may be caused by thyroid gland disorders or disorders of the pituitary gland (TSH production) or hypothalamus (thyrotropin-releasing hormone release). Thyroid hormone deficiency in infancy may cause mental retardation if it is not corrected immediately after birth. For this reason, many states require thyroid function tests in all newborns. In adults, thyroid deficiency may be caused by Hashimoto s thyroiditis, an immune disorder, or dietary iodine deficiency, in which case it is called simple goiter. The term "myxedema" has been used to refer to hypothyroidism of whatever cause. Myxedemas may... 

Hypothyrodism and hyperthyroidism can both be due to a number of causes, one of which is metabolic dysfunction. Hypothyroidism is caused by undersecretion, of thyroid hormones. In one form of childhood hypothyroidism, children born with abnormally small thyroids produce insufficient levels of the thyroid hormones T3 and T4, which are important for metabolically directed bone development. If detected in the first 6 months of life, this disorder can be treated with synthetic thyroid hormones such that its effects can be avoided. The most severe early onset hypothyroidisms are characterized by Cretinism, a type of dwarfism, and mental retardation. Adult hypothyroidism is called myxedema. Myxedema symptoms include slowed speech, yellowed skin, and generally slowed body functions. Myxedema can also be treated with synthetic T4, but if left untreated, can lead to coma. 

Liothyronine is used in the treatment of hypothyroidism, nontoxic goiter, cretinism, and myxedema. 

Severe hypothyroidism is called myxedema, which results in ... 

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