SALT LAKE CITY — It's hard to know whom among the elderly to screen for thyroid dysfunction because, when it comes to adults without thyroid-disease symptoms, current recommendations from various medical societies differ widely.
The American Thyroid Association recommends screening every 5 years for all women and men older than the age of 35 years. The American College of Physicians' guideline—although officially inactive because it's more than 5 years old—recommends screening only women who are older than 50 and who show incidental symptoms of thyroid disease. And the U.S. Preventive Services Task Force says there is insufficient evidence for or against screening anyone.
Nevertheless, Dr. Naushira Pandya said that the consensus among geriatricians is to screen men and women aged 65 years and older at least once, and thereafter if they develop symptoms of hypothyroidism or hyperthyroidism. The reason, she said, is that so many diseases and drugs common in elderly people can affect the thyroid.
Speaking at the annual symposium of the American Medical Directors Association, Dr. Pandya offered a list of conditions that warrant testing for thyroid dysfunction. These include previous thyroid disease or surgery; the presence of a goiter or nodule; type 1 diabetes; previous postpartum thyroid dysfunction; Down or Turner's syndrome; chronic kidney disease; previous irradiation of the head and neck; radical pharyngeal surgery; history of polycystic ovary syndrome; pituitary surgery or irradiation; and severe head injury.
The list of drugs that affect thyroid function is also lengthy. Lithium, iodine (including that in x-ray contrast media and kelp nutritional supplements), interleukin-2, and interferon-α may cause hypothyroidism, whereas iodine, interleukins, and interferons may cause hyperthyroidism, said Dr. Pandya of the department of internal medicine at Nova Southeastern University College of Osteopathic Medicine, Fort Lauderdale, Fla. In addition, glucocorticoids, iodine, propylthiouracil, β-blockers, and amiodarone may impair the conversion of T4 to T3, whereas dopamine, dobutamine, glucocorticoids, phenytoin, bromocriptine, and octreotide may suppress thyroid- stimulating hormone.
Carbamazepine, phenytoin, rifampin, and phenobarbital may increase clearance of T4, whereas salsalate, salicylates, nonsteroidal anti-inflammatory drugs, furosemide, and heparin may reduce binding of T4 to thyroid-binding globulin. Dr. Pandya also noted aluminum hydroxide, cholestyramine, ferrous sulfate, sucralfate, and cation exchange resins influence the absorption of thyroxine.
Compared with their younger counterparts, older people are more likely to have overt and subclinical hypothyroidism as well as subclinical hyperthyroidism and thyroid nodules, said Dr. Pandya, who is also director of the university's geriatric education center. The prevalence of overt hyperthyroidism and thyroid cancer is believed to be the same in young and old people. However, thyroid cancer in older adults tends to be a more aggressive disease than it is in younger people.
Signs and symptoms of hypothyroidism in older patients mimic certain processes of normal aging, including anorexia, cognitive decline, cold intolerance, constipation, dry skin, fatigue, hearing loss, hoarseness, paresthesia, slowed reflexes, and weakness.
“A high index of suspicion is important,” said Dr. Pandya. Symptoms of hyperthyroidism may be absent or subtle, or may be obscured by existing diseases. Cardiac complications such as atrial arrhythmias, heart failure, and angina are the most common indicators of the thyroid problem. A decrease in physical activity with fatigue, weakness, lethargy, agitation, confusion, and dementia are also common. Weight loss with anorexia may be present, and myopathy is predominant. Dr. Pandya said she had no relevant conflicts of interest to disclose.
'A high index of suspicion is important.' The symptoms may be absent or subtle, or obscured by existing diseases. DR. PANDYA