A Clinical Care Review for the Pharmacist: Recognizing and Treating Hypothyroidism

New treatment guidelines are changing the way that clinicians approach hypothyroidism.

Hypothyroidism is an endocrine condition that occurs when an underactive thyroid gland results in a deficiency in the production of thyroid hormones and a slowing of vital body functions.^1,2 Although this condition can affect anyone at any age, it occurs most frequently in individuals older than 60 years and risk increases as an individual ages.¹

Hypothyroidism is most prevalent among female patients and affects an estimated 10% of women and 6% of men.^1-4 The National Institute of Health’s National Endocrine and Metabolic Diseases Information Service estimates that approximately 4.6% of the US population 12 years and older has some degree of the condition.^2,3 Table 1^4-6 outlines the different types of hypothyroidism.

Updated Treatment Guidelines

In September 2012, the American Association of Clinical Endocrinologists and the American Thyroid Association jointly developed and updated clinical practice guidelines regarding optimal evaluation, diagnosis, treatment, and long-term care of patients with hypothyroidism. The full text of the updated guidelines can be found online at http://aace.metapress.com/content/ B67V7MK73G3233N2. The guidelines are scheduled to be published in the November/December 2012 issue of Endocrine Practice.^3,7

They contain 52 evidence-based clinical recommendations that were composed by the joint task force’s expert clinicians. Some of the key highlights and recommendations include^3,7:

• Most physicians can diagnose and treat hypothyroidism, but an endocrinologist should be consulted for those in the following patient populations: the pediatric patient population, pregnant patients or those planning to conceive, those with cardiovascular diease, and those with other endocrine diseases such as adrenal and pituitary disorders.
• A serum TSH (thyroid-stimulating hormone) is the single best screening test to diagnose hypothyroidism. It is not sufficient for assessing hospitalized patients or when central hypothyroidism is present or suspected. (Central hypothyroidism is due to a decrease in the secretion of TSH from the pituitary gland.)
• Hypothyroidism should be treated with levothyroxine (L-thyroxine or T4).
• No clinical data exist to support the effectiveness of the use of OTC products marketed for “thyroid support” or to promote “thyroid health.”
• Levothyroxine and levotriiodothyronine (T3) combinations, including desiccated thyroid, should not be used planning pregnancy.
• Mild TSH elevations in the elderly may be a normal manifestation of aging and not necessarily indicate hypothyroidism.
• When treating subclinical hypothyroidism (serum TSH <10 mIU/L), treatment should be tailored to the individual patient.

The most common cause of hypothyroidism is thyroiditis.^2-6 Although the incidence is rare, hypothyroidism can also manifest from too much or too little intake of dietary iodine or from abnormalities of the pituitary gland.^2-6

Recognizing the Symptoms

Hypothyroidism rarely causes symptoms in the early stages, but over time, if left untreated, it can lead to several medical problems, such as infertility, obesity, cardiovascular problems, and joint pain.^1-6

The symptoms associated with hypothyroidism can vary from patient to patient. Typically, elderly patients present with significantly fewer symptoms, which are often subtle or vague when compared with those experienced by younger patients.^1-6 Annual testing for those older than 60 years is highly recommended by many experts.¹

Early on, the most prevalent symptoms may include^1-6:

• Feeling run down, fatigued, or weak; lacking energy
• Unexplained weight gain with poor appetite
• Facial puffiness
• Cold intolerance
• Joint stiffness and muscle pain
• Constipation
• Dry skin and dry, brittle,
• Hair loss
• Decreased sweating
• Heavy or irregular menstrual periods or infertility issues
• Depression
• Bradycardia
• Hyperlipidemia

If left untreated, patients may also experience decreased taste and smell; hoarseness; puffy face, hands, and feet; slow speech; thickening of the skin; and thinning of the eyebrows.^1-6

The most severe of hypothyroidism, which rarely occurs, is myxedema coma.^1-6 It may be caused by an infection, illness, exposure to cold, or certain medications in individuals with untreated hypothyroidism.^1-6 The symptoms and signs associated with myxedema coma include below-normal temperature, shallow breathing, low blood pressure, low blood glucose, and unresponsiveness.^1-6

When hypothyroidism is suspected, the patient may present with a smaller than normal thyroid gland, but not in all cases.^1-6

Role of the Pharmacist

Although there is no cure for hypothyroidism, pharmacists can encourage patients by ensuring them that in most cases, this condition can be easily treated and managed with the use of synthetic thyroid hormone. Patient adherence to medication therapy is critical.

Levothyroxine is the most commonly prescribed pharmacologic agent for the treatment of hypothyroidism. Patients should be advised to never stop taking the medication even if they feel better unless told to do by their physician. Typically, therapy is initiated at the lowest dose possible to relieve symptoms and to achieve therapeutic levels.^1-6 This agent works best when taken on an empty stomach or within 1 hour before any other medications. During counseling, patients should be reminded to take medication daily at the same time each day. The 2012 recommendations state that L-thyroxine should be taken with water consistently 30 to 60 minutes before breakfast or at bedtime 4 hours after the last meal.⁷ Thyroid medication should not be taken at the same time as fiber supplements, calcium, iron, multivitamins, aluminum hydroxide antacids, or any medications that bind bile acids.^1-6 These medications should be taken at least 4 hours apart to avoid interactions.

Patients should also be advised to report any adverse effects or concerns, especially because excessive amounts of thyroid hormone can cause various adverse effects, such as palpitations, rapid weight loss, restlessness or shakiness, sweating, and insomnia.^1-6

With routine monitoring and proper treatment, patients with hypothyroidism can lead active, healthy lives.

Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.

References

• Hypothyroidism. National Endocrine and Metabolic Disease Information Service website. www.endocrine.niddk.nih.gov/pubs/hypothyroidism/. Accessed October 1, 2012.
• Hypothyroidism. US National Library of Medicine website. www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001393. Accessed October 1, 2012.
• American Association of Clinical Endocrinologists releases new jointly developed clinical guidelines for management of hypothyroidism in adults. American Association of Clinical Endocrinologists website. http://media.aace.com/press-release/american-association-clinical-endocrinologists-releases-new-jointly-developed-clinical. Accessed October 1, 2012.
• Hypothyroidism. Merck Manual for Healthcare Professionals online edition. www.merckmanuals.com/professional/endocrine_and_metabolic_disorders/thyroid_disorders/hypothyroidism.html. Accessed October 1, 2012.
• Brent GA, Davies TF. Hypothyroidism and thyroiditis. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 13.
• Kim M, Ladenson P. Thyroid. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 233.
• Clinical Practice Guidelines for Hypothyroidism in Adults. Co-sponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocrine Practice website. metapress.com/content/b67v7mk73g3233n2/fulltext.pdf. Accessed October 1, 2012.