Hypothyroidism in Women

Illustration istock Collection / thinkstockphotos.com T Hypothyroidism in Women Donna Dunn Thyroid disease is a major health issue in the United States. Approximately 20 million Americans have been diagnosed or are being treated for thyroid disease (American Thyroid Association, 2015). Hypothyroidism is the second most common type of endocrine disorder affecting women of reproductive age, but it can affect women across the lifespan. The thyroid maintains metabolism and vital body functions. It is located in the anterior neck just below the larynx and is composed of two lobes that straddle the trachea. Hypothyroidism occurs when the thyroid gland does not make enough thyroid hormone. Carla Turner About Hypothyroidism In women, the risk of developing hypothyroidism increases with age and during pregnancy, the postpartum period, and menopause (Garber et al., 2012). Iodine deficiency is the most common cause of hypothyroidism worldwide (Vanderpump, 2011). The most common cause of hypothyroidism in the United States, Hashimoto s thyroiditis, results from damage to the thyroid gland caused by chronic inflammation initiated and sustained by one s own immune system (Zaletel & Gaberšček, 2011). This autoimmune Abstract Hypothyroidism, a disease in which the thyroid gland does not make enough thyroid hormone, is the second most common endocrine disorder among women. Symptoms of hypothyroidism include fatigue, weight gain, alteration in cognition, infertility, and menstrual abnormalities. The most common cause of hypothyroidism in the United States is Hashimoto s thyroiditis. The American Thyroid Association recommends an initial screening for thyroid disease at age 35 years and every 5 years thereafter. Thyroid-stimulating hormone is highly sensitive to thyroid dysfunction and is used to evaluate thyroid disorders. Monotherapy with levothyroxine is the standard for treating hypothyroidism. Diagnosing hypothyroidism requires appropriate diagnostic tests to facilitate prompt diagnosis and treatment. http://dx.doi.org/10.1016/j.nwh.2015.12.002 Keywords hypothyroidism levothyroxine pregnancy T3 T4 TSH nwhjournal.com 2016, AWHONN 93

reaction results in the underproduction of thyroid hormone and is 5 to 10 times more likely to occur in women than men (Garber et al., 2012). Medical treatments can also cause hypothyroidism. The treatment of certain thyroid conditions, such as thyroid cancer, goiter, and Graves disease, may require surgical removal of a portion of the thyroid gland or a thyroidectomy. If enough of the gland is removed, the thyroid is unable to produce adequate thyroid In women, the risk of developing hypothyroidism increases with age and during pregnancy, the postpartum period, and menopause hormone, resulting in hypothyroidism. Additionally, some other thyroid conditions and cancers may require treatment with radioactive iodine or external radiation, which can damage the thyroid, usually resulting in overt hypothyroidism. Some medications can cause hypothyroidism by affecting the thyroid gland s production or release of hormones. Medications such as amiodarone, interferon, and lithium have been identified as a cause of hypothyroidism (Barbesino, 2010). Pathophysiology It is important to understand the function of the thyroid and the thyroid hormones thyroidstimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4). A normally functioning thyroid uses iodine from the diet to produce T4 and T3. The pituitary gland, about the size of a peanut and located at the base of the brain, produces TSH, which stimulates the thyroid gland to produce and release T3 and T4. Through a negative feedback loop, the pituitary produces TSH if T3 and T4 levels are low. The pituitary gland is regulated by the hypothalamus. The hypothalamus detects low levels of thyroid hormones and then responds by releasing thyrotropin-releasing hormone, which stimulates the pituitary gland to produce and release TSH to facilitate the thyroid gland to produce and release T3 and T4. This interaction continues in an effort to normalize blood levels of thyroid hormones. However, during primary hypothyroidism, disruption in the feedback loop is caused by the thyroid gland s diminished secretion of hormones. Secondary hypothyroidism produces Box 1. Symptoms, Assessment, and Diagnostic Findings Donna Dunn, PhD, CNM, FNP-BC, is an assistant professor; Carla Turner, DNP, ACNP-BC, is an instructor; both authors are at the School of Nursing, University of Alabama at Birmingham in Birmingham, AL. The authors report no conflicts of interest or relevant financial relationships. Address correspondence to: DonnaDunn@uab.edu. Symptoms Depression Fatigue Weight gain Constipation Muscle cramps, arthralgias Menorrhagia Infertility Sexual dysfunction Cold intolerance Carpal tunnel syndrome Sleep disorders Assessment Findings Dry, coarse skin Reduced body and scalp hair Dull facial expression Bradycardia Goiter Macroglossia Ascites Galactorrhea Slow relaxation of tendon reflexes Nonpitting edema of lower extremities Hoarseness Diagnostic Findings Hyponatremia Macrocytic anemia Decreased memory Hyperprolactinemia Elevated creatine kinase level Pituitary gland enlargement Delayed bone age Hypercholesterolemia Sources: Gaitonde, Rowley, and Sweeney (2012); Orlander (2015). 94 Nursing for Women s Health Volume 20 Issue 1

Photo rob original / thinkstockphotos.com disruption in the feedback loop because of problems at the level of the pituitary gland. Diagnosis Diagnosing hypothyroidism can be challenging; clinical manifestations are not a reliable method for diagnosing hypothyroidism. Women often present with myriad symptoms that are easily attributable to other disorders or simply to normal aging (see Box 1). It is important to obtain appropriate diagnostic tests to facilitate prompt diagnosis and treatment. A health history is useful to evaluate for symptoms of hypothyroidism, past treatment for hyperthyroidism, use of drugs that influence thyroid hormones, or a history of iodine deficiency. A focused physical examination would include assessing for coarse skin, delayed ankle reflex, and bradycardia, which, in one study, showed only a modest specificity in diagnosing hypothyroidism (Indra, Patel, Joshi, Pai, & Kalantri, 2004). Therefore, clinicians must rely on diagnostic work-up, assessment, and a woman s symptoms to facilitate accurate diagnosis of hypothyroidism. Because hypothyroidism is the result of inadequate levels of thyroid hormones T3 and T4 Women often present with myriad symptoms that are easily attributable to other disorders or simply to normal aging and because the pituitary gland regulates the release of these hormones by TSH, an objective diagnosis of hypothyroidism can be confirmed with laboratory evaluation of TSH and T4 levels. The primary screening test to evaluate thyroid function measures TSH level because, if T3 and T4 levels are low, the pituitary gland produces more TSH (Garber et al., 2012). If the TSH level is elevated, the next step is to measure free T4 or the free T4 index. The T3 level is not as useful in diagnosing hypothyroidism because it is usually the last thyroid hormone to become abnormally low (Garber et al., 2012). The T3 level can also be low without thyroid abnormalities, such as during acute illness. After diagnostic laboratory data are available, it is important to determine the type and possible cause of hypothyroidism. Hypothyroidism can be characterized as primary, subclinical, February March 2016 Nursing for Women s Health 95

The goal of treatment is symptom relief and prevention of complications of untreated hypothyroidism and central; these types are differentiated by TSH and T4 levels (Ross, 2015). Primary hypothyroidism is defined by an elevated TSH level and a low free T4 level; this type accounts for most cases of hypothyroidism (Ross, 2015). Subclinical hypothyroidism is characterized by a normal free T4 level with an elevated TSH level. Central hypothyroidism is defined as either secondary or tertiary and is usually associated with disorders involving the pituitary (secondary) or hypothalamus (tertiary). Central hypothyroidism is defined by a low T4 level, and TSH level may be low, normal, or elevated. Primary hypothyroidism accounts for most cases. Other tests exist in addition to a thyroid function test. A specialist can evaluate for anti thyroid microsomal antibodies, such as anti thyroid peroxidase, to further determine the cause of hypothyroidism. The presence of these antibodies indicates thyroid damage has occurred that may lead to hypothyroidism. This test might be indicated in a woman with a goiter or a symptomatic woman with a normal TSH level. Symptoms associated with hypothyroidism may mimic anemia and hypoglycemia. When other diagnoses aside from hypothyroidism are suspected, clinicians should consider measuring a complete blood cell count, TSH level, and fasting blood glucose level. Differential diagnoses of hypothyroidism may include disorders such as chronic fatigue syndrome, anovulation, dysmenorrhea, hypopituitarism, chronic inflammatory diseases, or other disorders of the thyroid gland. Furthermore, clinicians should evaluate for depression, dementia, or sleep disorders because of similarity of symptomatology. Treatment Indications Women with primary hypothyroidism should be treated. Additionally, women with subclinical hypothyroidism with a TSH level greater than 10 miu/l should be treated. Treatment of women with a TSH level less than 10 miu/l should be done on a case-by-case basis (Garber et al., 2012). Subclinical hypothyroidism is likely to progress to overt hypothyroidism if left untreated. Treatment is also suggested for pregnant women with hypothyroidism and for adults younger than 70 years who have a goiter, anti thyroid peroxidase antibodies, or symptoms of hypothyroidism (Almandoz & Gharib, 2012). Photo monkeybusinessimages / thinkstockphotos.com 96 Nursing for Women s Health Volume 20 Issue 1

The goal of treatment is symptom relief and prevention of complications of untreated hypothyroidism. Treatment is not advised for women with symptoms of hypothyroidism without laboratory confirmation (Garber et al., 2012). Monotherapy with levothyroxine is the standard for treating hypothyroidism (Garber et al., 2012). Women with hypothyroidism should be referred to an endocrinologist for the following: (a) difficulty maintaining a euthyroid state, (b) during pregnancy, (c) when planning to become pregnant, (d) cardiac disease, (e) presence of a nodule or other abnormal thyroid structural changes, (f) presence of other endocrine abnormalities such as pituitary and adrenal disorders, and (g) unusual causes of hypothyroidism related to malabsorption of levothyroxine (Garber et al., 2012). Dosage The initial dose of levothyroxine depends on a woman s age, body mass index, and presence of illnesses such as cardiac disease. Higher levothyroxine dosages may intensify angina and should be started at a lower dosage with close monitoring to avoid overreplacement. Overreplacement of thyroid hormones increases risk for osteoporosis and atrial fibrillation. However, young healthy adults and those undergoing a full thyroidectomy usually require a full replacement dose. Special dosage considerations for women over 60 years of age and those with ischemic heart disease should start at one fourth to one half of the expected dosage (Orlander, 2015). Pregnancy increases the requirements of thyroid hormones. Higher doses of levothyroxine during pregnancy are usually necessary, and clinicians should include levothyroxine with consideration to the trimester-specific reference range (Garber et al., 2012). Additionally, because some prenatal vitamins may affect absorption of levothyroxine, it is important to counsel women to take levothyroxine 2 to 3 hours before or after taking a prenatal vitamin (Almandoz & Gharib, 2012). It is important to measure the thyroid levels in pregnant women every 6 to 8 weeks or 4 weeks after a dosing change has been made. After a woman gives birth, she typically goes back to her prepregnancy dosage of levothyroxine. Follow-up Women whose symptoms have resolved and who have a therapeutic TSH level on the prescribed dosage of levothyroxine should undergo TSH level evaluation at least every 12 months. The TSH levels should also be re-evaluated 4 to 8 weeks after initiation or alteration of the dosage of levothyroxine. Serum TSH levels should be evaluated every 4 weeks during the first half Box 2. Risk Factors for Hypothyroidism Female Age >60 years Type 1 diabetes mellitus or other autoimmune disorders Graves disease Postpartum thyroiditis Turner syndrome and Down syndrome Primary pulmonary hypertension Lithium use Family history Amiodarone use Iodine deficiency Radiologic therapy, especially to the neck area Multiple sclerosis of pregnancy and less often during the second half. Women who were being treated for hypothyroidism before pregnancy usually require two additional doses weekly of their prepregnancy dose (Orlander, 2015). Once a diagnosis of hypothyroidism is confirmed, clinicians should provide education on the potential complications if the condition is left untreated Women should receive education on the signs and symptoms of hyperthyroidism that could occur from overtreatment. These include tachycardia, palpitations, and irregular heart rate, usually caused by atrial fibrillation. If hypothyroidism is overtreated, women may experience nervousness, insomnia, tremors, and chest pain. Clinicians should provide education on the importance of medication compliance and managing missed doses. Women should not double a dose for missed doses. Once a diagnosis of hypothyroidism is confirmed, clinicians should provide Sources: American Thyroid Association (2015); Garber et al. (2012). February March 2016 Nursing for Women s Health 97

education on the potential complications if the condition is left untreated. Hypothyroidism can result in physical and mental abnormalities. The severity is primarily attributable to the degree of thyroid hormone deficiency. A life-threatening but rare complication of untreated hypothyroidism is myxedema coma associated with severe hypothermia, bradycardia, seizures, and decreased cardiac output eventually resulting in coma (Citkowitz, 2014). Untreated hypothyroidism during pregnancy has been associated with a higher incidence of physical and mental birth defects (Berber, 2014). Untreated hypothyroidism can cause hyperlipidemia, which can contribute to the development of coronary Nurses are in an ideal position to identify women at risk and to educate them about hypothyroidism artery disease. Some studies have suggested a higher mortality with hypothyroidism and severe heart failure (Mitchell et al., 2013). Conclusion Hypothyroidism is an endocrine disorder that disproportionately affects women. The signs and symptoms of hypothyroidism are subtle and are usually attributed to other conditions, such as depression and natural aging. There is controversy among professional organizations concerning recommendations for screening. Given the lack of data supporting population-based screening, delegates from the Endocrine Society, American Thyroid Association, and American Association of Clinical Endocrinologists arrived at a consensus. They recommended screening for groups at risk for hypothyroidism (see Box 2), including pregnant women, women older than 60 years, and those with a family history of thyroid disorders (Almandoz & Gharib, 2012). Nurses are in an ideal position to identify women at risk and to educate them about hypothyroidism. NWH References Almandoz, J., & Gharib, H. (2012). Hypothyroidism: Etiology, diagnosis, and management. The Medical Clinics of North America, 96(2), 203 221. doi:10.1016/j.mcna.2012.01.005 American Thyroid Association. (2015). About hypothyroidism. Falls Church, VA: Author. Retrieved from http://www.thyroid.org/ media-main/about-hypothyroidism Barbesino, G. (2010). Drugs affecting thyroid function. Thyroid, 20(7), 763 770. doi:10.1089/ thy.2010.1635 Berber, E. (2014). Complications of hypothyroidism: What may happen if the disorder is untreated. Retrieved from http://www.endocrineweb.com/conditions/hypothyroidism/ complications-hypothyroidism Citkowitz, E. (2014). Myxedema coma or crisis. Retrieved from http://emedicine.medscape.com/ article/123577-overview#a5 Gaitonde, D. Y., Rowley, K. D., & Sweeney, L. B. (2012). Hypothyroidism: An update. South African Family Practice, 54(5), 384 390. Garber, J. R., Cobin, R. H, Gharib, H., Hennessey, J. V., Klein, I., Mechanick, J. I.,... American Association of Clinical Endocrinologists & American Thyroid Association Taskforce on Hypothyroidism in Adults. (2012). Clinical practice guidelines for hypothyroidism in adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocrine Practice, 18(6), 988 1028. Indra, R., Patil, S. S., Joshi, R., Pai, M., Kalantri, S. P. (2004). Accuracy of physical examination in the diagnosis of hypothyroidism: A cross-sectional, double-blind study. Journal of Postgraduate Medicine, 50(1), 7 11. Mitchell, J. E., Hellkamp, A. S., Mark, D. B., Anderson, J., Johnson, G. W., Poole, J. E.,... Bardy, G. H. (2013). Thyroid function in heart failure and impact on mortality. Journal of the American College of Cardiology, 1(1), 48 55. Orlander, P. R. (2015). Hypothyroidism: Practice essentials. Retrieved from http://emedicine.medscape.com/article/122393-overview Ross, D. (2015). Diagnosis of and screening for hypothyroidism in nonpregnant adults. Retrieved from: http://www.uptodate.com/contents/ diagnosis-of-and-screening-for-hypothyroidism -in-nonpregnant-adults?source=see_link Vanderpump, M. P. (2011). The epidemiology of thyroid disease. British Medical Bulletin, 99, 39 51. doi:10.1093/bmb/ldr030 Zaletel, K., & Gaberšček, S. (2011). Hashimoto s thyroiditis: From genes to the disease. Current Genomics, 12(8), 576 588. doi:10.2174/1389202117981207 98 Nursing for Women s Health Volume 20 Issue 1