Managing Hyperthyroidism in Older Adults

Thyroid disorders affect nearly a quarter of individuals ≥ 65 years, and their prevalence in this group is expected to rise as the population progressively ages and people live longer.

These conditions, which include hypothyroidism, hyperthyroidism, nodules, and thyroid cancer, can be difficult to diagnose in older adults because symptoms may be more subtle than in younger individuals and are often mistakenly viewed as part of “normal aging.” But a missed diagnosis can have serious consequences for heart, metabolic, bone, and mental health.

Carolyn Dacey Seib, MD, MAS, associate professor, Department of Surgery, Stanford University School of Medicine, Palo Alto, California, sees older patients whose symptoms might have been “subacute” at first but who don’t receive an adequate evaluation for a functional thyroid disorder. “It’s often not until some other complications occur or symptoms become extremely bothersome that they get the evaluation they need,” she told Medscape Medical News.

Given the patient health risks, difficulty of diagnosis, and increasing prevalence, it’s particularly important for clinicians to be aware of how thyroid disorders present in older adults and how to diagnose and treat them.

This article, the first in a two-part series on thyroid disease in older adults, will focus on hyperthyroidism. The second article will focus on hypothyroidism.

Overt vs Subclinical Disease

Hyperthyroidism involves excess production of thyroid hormone. The most common cause is the autoimmune disorder Graves’ disease, which is most prevalent among people aged 40-60 years, particularly women, but also affects older adults. The prevalence of two other common causes of hyperthyroidism in this population — toxic multinodular goiter and toxic nodular adenomas — increases with age.

Additionally, roughly one fifth of patients experience hyperthyroidism following contrast radiography involving iodine administration, although this is often transient.

Hyperthyroidism can be overt or subclinical. Overt hyperthyroidism is defined by low levels of thyroid-stimulating hormone (TSH) coupled with elevated circulating free triiodothyronine (T3) and free thyroxine (T4). In patients with subclinical hyperthyroidism, serum TSH is low or undetectable, but T3 and T4 levels are normal.

Hyperthyroidism prevalence in older adults is estimated to range from 0.5% to 4% but may reach as high as 5% in older women. Subclinical disease is more common than overt hyperthyroidism in older adults and more common in women than in men — especially in patients > 70 years.

Although the progression of subclinical to overt hyperthyroidism is “infrequent,” it can occur, so subclinical hyperthyroidism should be taken seriously. Notably, the risk for atrial fibrillation (AF) — a common sign of hyperthyroidism in elderly patients — is the same whether the disease is subclinical or overt.

Surprising Presentations

Two thirds of older adults present similarly to younger patients with symptoms consistent with sympathetic overactivity, such as tremors, anxiety, palpitations, and heat intolerance. But one third do not and have what’s called apathetic hypothyroidism.

Older adults with apathetic hyperthyroidism, also called apathetic thyrotoxicosis, may present with symptoms more commonly associated with hypothyroidism, such as fatigue, weakness, depression, weight loss, and dyspnea, said Scott Isaacs, MD, president-elect of the American Association of Clinical Endocrinology.

Other symptoms of apathetic hyperthyroidism include predominantly cardiovascular symptoms (AF and heart failure), pulmonary hypertension, and confusion. Mischaracterizing this condition as a primary psychiatric disorder increases the risk of missing an early diagnosis, potentially leading to a thyrotoxic crisis, which can be fatal.

Hyperthyroidism can present in other unusual ways in older adults. Its neuropsychiatric symptoms can mimic dementia, Isaacs told Medscape Medical News. Although many people with hyperthyroidism have diarrhea or hyperdefecation, older adults may instead experience constipation.

Detection and Diagnosis

Blood tests are helpful in diagnosing hyperthyroidism; start with serum TSH, free T4, and total T3. If hyperthyroidism is indicated, additional tests are necessary to determine its etiology.

Isaacs recommended an antibody panel that measures levels of thyroid peroxidase, thyroglobulin antibodies, thyrotropin-receptor antibodies, and thyroid-stimulating immunoglobulin. Elevated levels of these antibodies are a marker of Graves’ disease, he noted.

A radioactive iodine uptake test should be conducted if the clinical presentation and laboratory data suggest toxic adenoma or toxic multinodular goiter. It measures the percentage of the administered radioactive iodine concentrated in the thyroid tissue after 24 hours.

“The pattern of uptake is key in differentiating between different causes of hyperthyroidism,” Seib said. Uptake is diffuse and high in Graves’ disease, localized in the nodule with the rest of the gland suppressed in toxic adenoma, and marked by areas of intense activity with areas of reduced activity in toxic multinodular goiter,” she explained. Finally, an ultrasound of the thyroid gland can assess nodules and vascularity.

“Antibody testing should be used in combination with the clinical picture, thyroid hormone testing, and a thyroid scan and uptake to help make the diagnosis,” Isaacs said.

Patients who take large doses of biotin supplements may have false abnormalities in thyroid function tests that can mimic hyperthyroidism. It’s important to conduct a detailed review of medications, including dietary supplements, when evaluating thyroid function. Other drugs that may cause hyperthyroidism include lithium and immune checkpoint inhibitors.

Risks of Untreated Hyperthyroidism

Untreated hyperthyroidism carries several serious risks for older adults, including the development of cognitive disorders. Although the literature is mixed, there is “ no conclusive evidence” regarding the degree of risk.

Osteoporosis is one of the most common conditions affecting older adults with untreated hyperthyroidism, and it poses the risk for fractures, Seib said.

AF, estimated to be present in up to 20%-30% of older adults with hyperthyroidism (especially secondary to toxic nodules), is sometimes the condition’s “only clinical sign.”

While younger patients with hyperthyroidism often present with sinus tachycardia, the presence of palpitations may be less likely or “masked” in older adults. Other cardiovascular changes associated with hyperthyroidism (both overt and subclinical) include widened pulse pressure, exercise intolerance, increased cardiac mass, and increased cardiovascular mortality.

Long-standing untreated hyperthyroidism can lead to a thyrotoxic crisis, also called a thyroid storm, a “rare, life-threatening clinical condition characterized by severe clinical manifestations of thyrotoxicosis.” The condition often is precipitated by an acute event and can cause death from cardiovascular collapse.

TSH, free T4, and T3 levels should be immediately assessed if suspicious symptoms occur. Treatments include beta-blockers, methimazole or propylthiouracil in high doses, saturated potassium iodide (Lugol’s iodine) solution, and glucocorticoids. Patients should be closely monitored in an intensive care unit.

Nonsurgical Treatment Approaches

“For any patient, but especially for older adults, the goal of treatment is to render the patient euthyroid as soon as possible, while considering trade-offs, available treatments, side effects, and the need for additional treatments over time,” Seib said. Nonsurgical treatment options include radioactive iodine ablation therapy, antithyroid medications, and radiofrequency ablation (RFA).

Symptoms of sympathetic activation can be treated with beta-adrenergic blockade, which decreases both heart rate and systolic blood pressure and may improve tremors, irritability, emotional lability, and exercise intolerance. For patients with AF, anticoagulation therapy may be necessary.

Methimazole is the main drug used in younger and middle-aged patients with Graves’ disease or subclinical hyperthyroidism, and it can rapidly normalize thyroid function. It is the preferred medication in older adults as well. This is important because hyperthyroidism in an older person can pose potentially lethal cardiac arrhythmias.

Seib said that after a course of treatment of 12-18 months, patients with Graves’ disease may go into remission, while patients with toxic adenoma or multinodular goiter might need medications long-term. “Medications may be safe and a good option for many patients but may have side effects and contraindications, such as liver toxicity and agranulocytosis, which limit their use,” she warned. Other side effects include rashes, arthralgias, and myalgias.

Another option for toxic adenomas and Graves’ disease is radioactive iodine, which has high efficacy and is cost-effective. The dose is calculated on the basis of the previous thyroid uptake scan.

“It’s a durable treatment of hyperthyroidism, but there can be a period of increased hypothyroidism after the initial treatment or the development of long-term hypothyroidism,” Seib noted. An additional drawback to this management approach is that hyperthyroidism is reversed gradually, but cardiac issues may need to be managed aggressively until the thyrotoxic state is reversed.

RFA is a new treatment option for thyroid nodules, especially for toxic adenomas, Seib said. “The procedure can be done in the clinic and doesn’t require anesthetic. A probe is inserted in the nodule under ultrasound guidance and is used to burn the nodule. The thermal destruction can address the hyperthyroidism and lead to a reduction in nodule size.”

The procedure tends to be more effective for smaller nodules, she noted. “For larger ones, there is a higher risk of hyperthyroidism recurrence, necessitating retreatment with RFA or other modalities.”

Risks for RFA include injury to local structures from the spread of internal heat, she warned. “But overall, those risks are lower than the risks involved with thyroidectomy. And one of the biggest benefits of RFA is that it’s rare for patient to end up with hypothyroidism after the procedure.”

Surgery Considerations

For some patients, thyroidectomy is the best treatment option.

“In an older patient who’s relatively healthy, decision-making regarding surgery is likely to be similar to that of younger patients,” Seib said. But for patients in their seventies and eighties, with more limited life expectancy, decisions should focus on addressing problems that affect quality of life and reducing the risk for complications.

Seib regarded thyroidectomy as a “good option” in patients with toxic multinodular goiters, especially if the goiters are large and the patient has compressive symptoms, such as difficulty swallowing, globus sensation, shortness of breath when lying flat, or dysphagia. In the case of multinodular goiter with most functional nodules on one side, based on a thyroid uptake scan, thyroid lobectomy has a lower risk for complications, such as hematoma, than total thyroidectomy.

Even with a partial thyroidectomy, there’s a 20% chance that the patient will require thyroid hormone replacement, Isaacs pointed out, although there’s an 80% chance that the patient will achieve normal thyroid levels.

Total thyroidectomy has the benefit of “quickly and expeditiously treating hyperthyroidism from Graves’ disease,” Seib said. “The risk of complications after thyroidectomy depends on the patient’s age, comorbidities, and functional status.” Frailty increases the risk for complications.

Surgery carries the risks for hypoparathyroidism, which results from accidental injury to the parathyroid glands and can lead to long-term dependence on calcium supplementation. The risks tend to be lower in the hands of an experienced surgeon, Seib noted.

Shared Decision-Making

For any patient with hyperthyroidism, including older adults, shared decision-making is key, Seib said. “Consider what to prioritize, risks and benefits of each treatment option, which has the fewest risks based on comorbidities, the specific pathology, and how to make sure you don’t adversely affect the patient’s quality of life, especially if their life expectancy is limited.”

Patients considering surgery should consult a surgeon who “knows how to assess risk, including an evaluation of frailty and what symptoms are most bothersome, and then determining together which treatment approach will work best,” Seib added.

Additional considerations in treating patients with hyperthyroidism involve making sure their holistic needs are met, including adequate nutrition, mobility management, regulation of the home environment (including temperature), and psychosocial support.

Seib received funding from the National Institute on Aging. Isaacs reported no relevant financial relationships.

Batya Swift Yasgur, MA, LSW, is a freelance writer with a counseling practice in Teaneck, New Jersey. She is a regular contributor to numerous medical publications, including Medscape Medical News and WebMD, and is the author of several consumer-oriented health books, as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoir of two brave Afghan sisters who told her their story).