Author: Kathleen Pace Murphy, PhD, MS, GNP-BC
Hypothyroidism is a deficiency of thyroid hormones.
Approximately 9.6 million Americans have hypothyroidism (Carroll, 2009).
Hypothyroidism is more common in women than in men (Carroll, 2009).
Hypothyroidism is common in older adults and increases with age. Hypothyroidism often presents subtle,, non-specific symptoms. (The American Thyroid Association, 2012).
There are four types of hypothyroidism:
- Primary, the most common due to disease of the thyroid.
- Secondary hypothyroidism is due to disease in the pituitary.
- Tertiary hypothyroidism is due to disease of the hypothalamus.
- Subclinical hypothyroidism is an elevation of thyroid stimulating hormone (TSH) with normal T4 (thyroxine).
Contributing factors to hypothyroidism may be:
- endemic iodine deficiency or iodine excess
- iatrogenic secondary to thyroid surgery
- radioablation or radiation to the neck
- medications, such as amiodarone or lithium
- congenital absence of the thyroid gland
- autoimmune disorders such as Hashimoto's thyroiditis
During your review of the system, ask the patient if they are experiencing:
During physical exam, pay particular attention to the following:
- course dry skin
- hair loss
- cold intolerance
- menstrual irregularities (adult female population)
- cognitive/ memory changes.
||Weight gain and bradycardia
||Dull expression, swollen face, periorbital edema, decreased auditory acuity, swollen tongue, hoarseness, enlarged thyroid gland (goiter), glandular atrophy and thyroid nodules.
||Bradycardia, LV hypertrophy, mild hypotension or diastolic hypertension, decreased heart sounds.
||Bradypnea, diminished vital capacity and total lung capacity, dyspnea
||Hypoactive bowel sounds and abdominal bloating
||Swollen hands, swollen feet and leg edema
||Dementia, paranoid ideation, slow delayed reflexes and cerebellar ataxia
||Dry skin, pale, course dry hair, brittle nails, hair loss, and temporal thinning of eyebrows
Differential diagnosis for hypothyroidism includes:
- Coronary heart disease
- Congestive heart failure
- Kidney failure
- Nephrotic syndrome
- Chronic kidney disease
Diagnostic tests to order if you suspect hypothyroidism include:
- Thyroid panel (TSH, Free T4)-
- Overt hypothyroidism will demonstrate an increase in TSH and a decrease in T3 and T4 levels
- Subclinical hypothyroidism may show an increased but normal level of TSH with normal levels of free T4
- CBC for anemia
- Electrolytes (hyponatremia)
- Glucose (hypoglycemia)
- Lipid panel
- Daily thyroid replacement.
- Thyroid replacement doses are based on laboratory results.
- Older adults may metabolize T4 more slowly than younger persons. Dosage adjustment may be necessary.
- When prescribing a daily thyroid replacement remember a few points:
- Prescribe with caution in older adults with cardiovascular co-morbidities.
- Educate patients about how to take medications – same time each day, on an empty stomach, full glass of water.
- Avoid concomitant use with aluminum hydroxide antacids as it prevents absorption of the thyroid replacement.
- Avoid calcium supplements within 4 hours of thyroid replacement due to decrease in absorption of thyroid replacement.
- Thyroid replacement may interfere with the MOA of the following medications: tricyclic antidepressants, aminophylline, theophylline, warfarin, phenytoin, carbamazepine, beta blockers, digoxin and testosterone (DeLong, 2012).
Agency for Healthcare Research and Quality (2010). Thyroid function tests: Diagnoses and monitoring of thyroid function disorders in adults. Retrieved from:
http://www.guideline.gov/content.aspx?id=38907&search=hypothyroidism Last accessed November 1, 2013. Carroll, P. (2009). Hypothyroid disease. Evidence –based nursing monographs. Retrieved from http://www.nursingconsult.com/das/news/body/206944645-2/ebnm/0/214405/1.htm Last accessed June 23, 2010.
DeLong, M.F. (2012). Thyroid dysfunction. CME Resource. Retrieved from www.NetCE.com June 23, 2010.
The American Thyroid Association. (2012). Thyroid Disease in the Older Patient. Retrieved from http://www.thyroid.org/patients/patient_brochures/older_patient.html. Last accessed November 1, 2013.