Hypothyroidism Issue in the US - Term Paper Example

Hypothyroidism Hypothyroidism is next only to diabetes mellitus as the most common endocrine disorder in the United s and its prevalence may be as high as 18 cases per 1,000 persons in the general population. The under activity of the thyroid gland causes hypothyroidism. Its management focuses on ensuring that patients receive appropriate thyroid hormone replacement therapy and monitoring their reaction. Hormone replacement should be initiated in a low dosage, particularly in the elderly and in patients prone to cardiac problems. The dosage should be gradually increased, with regular monitored of hormone levels that may vary from six to eight weeks after any dosage change. Once a stable dosage is obtained, annual monitoring of the thyroid-stimulating hormone (TSH) level is probably unnecessary. After full replacement of thyroxine (T4) using levothyroxine, the addition of triiodothyronine (T3) in a low dosage may be beneficial in some patients who continue to have mood or memory problems. The management of patients with subclinical hypothyroidism (a high TSH in the presence of normal free T4 and T3 levels) remains controversial. In these patients, physicians should weigh the benefits of replacement (e.g., improved cardiac function) against problems that can accompany the excessive use of levothyroxine (e.g., osteoporosis). Hypothyroidism is becoming a very common problem. It is essential that this disease is diagnosed at an early stage and medications to be given at a regular interval. Introduction Hypothyroidism is an underactive thyroid gland. The thyroid gland can’t make enough thyroid hormone to keep the body running normally. People are hypothyroid if they have too little thyroid hormone in the blood (American Thyroid Association, 2005). The thyroid is a gland in the lower neck that makes iodine-containing hormones that regulate growth, brain development, and metabolism. Hypothyroidism occurs when the gland is absent, abnormally developed, destroyed, or reduced in size, or the production of thyroid hormones is decreased or absent (Scheinberg, 2006). It is usually due to primary thyroid gland failure secondary to chronic autoimmune thyroiditis (Hashimotos disease), or follows radioactive iodine therapy or thyroidectomy. This review article will help to understand the basic symptoms, causes, the diagnosis and management of the disease. Thyroid Dysfunction is common disorder of the thyroid gland. In the United States, hypothyroidism is present in 4.6% of the population (clinical, 0.3%; and subclinical, 4.3%) and hyperthyroidism in 1.3% (clinical, 0.5%; and subclinical, 0.7%). A long-term study in the United Kingdom found the incidence of hyperthyroidism was 0.8 per 1000 women annually, and hypothyroidism was 3.5 per 1000 women annually (Topliss and Eastman, 2004). Hypothyroidism is a serious condition with an insidious onset. The incidence is 3.5 per 1,000 in women and 0.6 per 1,000 in men. The probability of developing hypothyroidism increases with age and reaches 14 per 1,000 in women aged between 75–80 years. Hypothyroidism can either be congenital or acquired. Complications of hypothyroidism can include Coronary Heart Diseases, premature labour, fetal loss, stillbirth and, on the odd occasion results in coma. Function of Thyroid Gland and Symptoms of Hypothyroidism The thyroid gland is found in the neck. It lies in front of the wind-pipe (trachea), above the level of the collar-bones and measures approximately 2 by 4 cm. It secretes hormones, which are chemicals produced by the body to help regulate body functions. Hormones are sometimes called chemical messengers. The thyroid hormones are thyroxine (also called T4 because it contains four iodine atoms) and triiodothyronine (also called T3 because it contains three iodine atoms). These are released into the blood stream. T3 speeds up the bodys metabolism by encouraging the cells, in the muscles or the skin for instance, to work faster or to grow. Most of the T3 in the blood is converted from T4. Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormones. This tends to slow down the bodys functions. Symptoms include tiredness, constipation and sensitivity to the cold (BUPA, 2004). Causes of hypothyroidism There can be many reasons why the cells in the thyroid gland cannot make enough thyroid hormone. The following are some of the major causes: Iodine insufficiency The chemical element iodine is a major component of thyroid hormones. Worldwide, a deficiency of iodine in the diet is the leading cause of hypothyroidism. Autoimmune hypothyroidism In countries where the amount of iodine in the diet is adequate, the main cause of hypothyroidism is "autoimmune hypothyroidism". Antibodies are proteins designed to defend the body from foreign organisms, such as bacteria and viruses. In autoimmune diseases, antibodies attack the body itself. In autoimmune hypothyroidism, antibodies destroy thyroid gland cells preventing the gland from being able to release normal amounts of thyroid hormones. A condition known as Hashimotos thyroiditis is associated with autoimmune hypothyroidism. It results in goitre, a swelling of the thyroid gland that is visible as a lump on the neck. With no goitre the condition may be called atrophic thyroiditis or primary myxoedema (BUPA, 2004). Treatment for hyperthyroidism Hyperthyroidism is the result of an overactive thyroid gland. Treatments for hyperthyroidism, such as surgery or treatment with radioactive iodine or other antithyroid drugs can often result in hypothyroidism. Radiation treatment: Some people with Graves’ disease, nodular goiter, or thyroid cancer are treated with radioactive iodine (I-131) for the purpose of destroying their thyroid gland. Patients with Hodgkin’s disease, lymphoma, or cancers of the head or neck are treated with radiation. All these patients can lose part or all of their thyroid function. Thyroiditis: Thyroiditis is an inflammation of the thyroid gland, usually caused by an autoimmune attack or by a viral infection. Thyroiditis can make the thyroid dump its whole supply of stored thyroid hormone into the blood at once, causing brief hyperthyroidism (too much thyroid activity); then the thyroid becomes underactive (American Thyroid Association, 2005). Other causes: Congenital hypothyroidism is a condition where a newborn has decreased or absent thyroid function and thyroid hormone production (Scheinberg, 2006). With treatment, babies with congenital hypothyroidism develop normally. It is also known that inflammation of the thyroid gland (thyroiditis) due to infection can lead to hypothyroidism. Also, disorders of the hypothalamus and pituitary gland, both of which are involved in the overall regulation and production of thyroid hormones, can lead to hypothyroidism. Risk factors for hypothyroidism Hypothyroidism is more common in older people. Thyroid disease affects up to 0.5 percent of the population of the United States. Its prevalence is higher in women and the elderly. Autoimmune hypothyroidism is more likely in those who have other conditions resulting from an autoimmune disorder such as type 1 diabetes mellitus, vitiligo and Addisons disease. Some medicines can affect the normal functioning of the thyroid gland. These include lithium carbonate (for bipolar disorder) and amiodarone (for heart rhythm abnormalities) (BUPA, 2004). If untreated, congenital hypothyroidism can lead to severe mental retardation and growth retardation. However, if detected early at birth when the brain and nervous system is not yet fully developed, thyroid hormone replacement could prevent damage (Scheinberg, 2006). Symptoms of hypothyroidism The symptoms of hypothyroidism can primarily be very mild and develop slowly. It is possible to have some of these symptoms before the amount of thyroid hormone drops below normal. This type of mild hypothyroidism is called sub-clinical hypothyroidism. In this case it is essential the patients affected need to be monitored by their doctor, who will watch out for further symptoms. The symptoms of hypothyroidism relate to a general "slowing down" of the bodys functions. Such as: feeling tired and sleeping excessively easily feeling the cold dry and thickened skin coarse, thinning hair and eyebrows and brittle nails sore muscles, slow movements and weakness depression and problems with memory and concentration weight gain constipation fertility problems and increased risk of miscarriage heavy, irregular or prolonged menstrual periods There may also be swelling of the thyroid gland in the neck - goitre. Intermittently, a thyroid problem, such as thyroiditis, can resolve on its own without the need for treatment. However in general, if hypothyroidism is not treated, the symptoms slowly get worse and it becomes more and more difficult to function normally. Diagnosis of hypothyroidism Many of the above symptoms can be caused by conditions other than underactive thyroid. However, anyone who experiences these symptoms should consult their GP. A doctor will usually discuss symptoms, perform a physical examination and then request some blood tests if he or she suspects hypothyroidism. The first step in diagnosing hypothyroidism is to measure TSH (thyroid stimulating hormone). When the thyroid gland is not producing enough thyroid hormone, the TSH level is raised. When this abnormality is found, T4 (thyroxine) is also measured, and in autoimmune hypothyroidism or hypothyroidism due to treatment of hyperthyroidism, T4 is low. When levels of TSH and thyroid hormones are difficult to interpret, other causes of hypothyroidism may be suspected. The diagnosis of autoimmune hypothyroidism is usually confirmed by the presence of particular antibodies in the blood. Other blood tests or added investigations may also be needed. These could include an ECG (heart tracing) or a magnetic resonance imaging (MRI) scan to examine the nature and extent of a goitre. Treatment The management of hypothyroidism focuses on ensuring that patients receive appropriate thyroid hormone replacement therapy and monitoring their response. Hormone replacement should be initiated in a low dosage, especially in the elderly and in patients prone to cardiac problems (Hueston, 2001). Thyroxine (T4) can be given in tablet form. The body is able to convert this to T3 just as it would if the thyroid gland were producing the thyroxine normally. It can take some time to get the dose right. It is usual to start with a low dose, building up gradually every six weeks and adjusting the dose according to TSH levels. People usually feel much better once they are taking thyroxine. Side-effects are unusual because a missing hormone is simply being replaced. However, if too much replacement thyroxine is given, symptoms of an overactive thyroid may be experienced. People suffering from subclinical hypothyroidism may undergo any treatment, though doctors vary in their approach. Some prefer to offer treatment while others recommend frequent monitoring of hypothyroidism. Once the correct dose of thyroxine replacement has been established, it is usual to have annual checks of TSH (BUPA, 2004). Impact on other organs/systems Thyroid hormones are critical to cell and organ metabolism. With an inadequate supply, organ tissues do not grow or mature, energy production declines, and the action of other hormones is affected. Neurologic: In spite of the term coma, major changes in cognition, such as lethargy or stupor, do not exclude the diagnosis of myxedema coma/crisis. The exact mechanisms causing changes in mental status are not known. Reductions in cerebral blood flow and oxygen delivery, reduced oxygen and glucose consumption, and the lack of thyroxine (T4) and triiodothyronine (T3) influence brain function, and all must be involved. Hyponatremia brought on by renal dysfunction may be an additional cause of altered mental function. Cardiovascular : The heart is profoundly depressed with bradycardia and decreased contractility causing low stroke volume and cardiac output. These changes are caused by decreased production of myocyte contractile proteins and enzymes, including NA+/K+ ATPase, because of low levels of gene transcription in the absence of T3. Pulmonary : Typically, the lungs are not severely affected. Respiratory muscle dysfunction may be compromised, and depressed ventilatory drive and increased alveolar-arterial oxygen gradient are common. Hypothyroidism may also have a direct impact because the condition can cause obstructive sleep apnea that resolves with thyroid replacement Renal : Kidney function may be severely compromised, partly because of low cardiac output and vasoconstriction that causes a low glomerular filtration rate. Gastrointestinal : Severe and even mild hypothyroidism cause slowed intestinal motility. Patients with myxedema coma can present with gastric atony, megacolon, or paralytic ileus. Malabsorption has also been reported. Ascites, while uncommon, may be due to increased capillary permeability, congestive heart failure, or other mechanisms (WebMD, 1996). Conclusion Hypothyroidism is a serious problem particularly among the women. Hypothyroidism cannot be cured, but it can be completely controlled. It is treated by replacing the amount of hormone that your own thyroid can no longer make, to bring T4 and TSH back to normal levels. The basic aim of treatment is to get and keep your TSH in the normal range. Babies with congenital hypothyroidism must get regular treatments and have their TSH levels checked at regular intervals as they grow, to prevent mental retardation and stunted growth. The early diagnosis and treatment of hypothyroidism can prevent further health complications. References American Thyroid Association, (2005) Hypothyroidism [online]. Available from: [Accessed 24 April 2006] BUPA, (2004). Underactive thyroid (hypothyroidism). [Online]. Available from: [Accessed 24 April 2006] Hueston, W.J. (2001). Treatment of Hypothyroidism. Am Fam Physician Vol 64 no.10 p1717-24. Scheinberg, D. (2006) Congenital Hypothyroidism [online]. EBSCO Publishing. [Online]. http://healthlibrary.epnet.com/print.aspx?token=d5eb4158-6631-4a59-9f6a-dde11c3ac74c&chunkiid=102705> [Accessed 24 April 2006] Topliss, D.J. and Eastman, C.J. (2004) Diagnosis and management of hyperthyroidism and hypothyroidism. Med J Aust 180: p186–193. WebMD, (1996) Myxedema Coma or Crisis. [Online]. Available from: [Accessed 24 April 2006] Read More