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The thyroid gland is found in the neck, on either side of the voice box. This gland produces thyroid hormone, which directly influences many bodily processes. Thyroid hormone is especially important for normal metabolism and energy levels. Levels of thyroid hormone tend to decrease with age, but the body makes up for this by decreasing the breakdown of thyroid hormone. So, resting levels are usually normal in healthy older people.

Thyroid disorders can cause either low hormone levels or high hormone levels, depending on the type of problem. In hypothyroidism, the thyroid gland doesn't produce enough thyroid hormone. In hyperthyroidism, it produces too much. If either of these two conditions goes untreated, a goiter may develop, which means that the thyroid gland gets bigger.

Thyroid disorders are twice as common in older adults as in younger people. Hypothyroidism is the most common problem.

In hypothyroidism, blood levels of thyroid hormone are low. In older adults, it is most often caused by an immune form of thyroid destruction called Hashimoto's disease or because of earlier treatment for hyperthyroidism. Thyroid levels can also be temporarily low as a secondary effect from another illness, such as sudden infection.

In up to 10% of older adults, hypothyroidism is "subclinical." This means that resting thyroid levels are normal, but the thyroid gland has trouble responding to bodily changes. Subclinical hypothyroidism can cause heart problems, such as hardening of the arteries and heart attack.

Symptoms: The classic signs of hypothyroidism are lack of energy, depressed mood, and weight gain. However, older adults often have signs and symptoms that are not typical. These include dry skin, slowed thinking, weakness, constipation, anemia, low sodium levels in the blood, arthritis, numbness, and walking problems. These general symptoms are often confused with other illnesses and frequently thought of as being due to old age.

In addition, symptoms are usually subtle initially and progress slowly, making thyroid disease even more difficult to recognize and treat.

Hypothyroidism may cover up or look like many of the common illnesses seen in aging. Some medications commonly taken by older people (eg, corticosteroids or phenytoin) can also cause low thyroid levels.

Diagnosis: A characteristic history and physical examination can suggest hypothyroidism in older adults. A puffy face (especially around the eyes) and slowed tendon reflexes (eg, the knee-jerk reflex) are clues. However, because most symptoms in older adults are vague and may misleadingly suggest other diseases, diagnosis can be difficult.

Blood tests are needed to evaluate levels of thyroid hormone in the blood to detect most cases of hypothyroidism among older adults. Because thyroid levels are normal in subclinical hypothyroidism, additional blood tests may be needed to find increased levels of thyroid-stimulating hormone (TSH). TSH is a hormone that tells the thyroid gland when to produce more thyroid hormone. TSH is produced by the pituitary gland (also called the master gland) when levels of thyroid hormone decrease. Increased TSH levels suggest that the pituitary gland is constantly telling the thyroid gland to produce more thyroid hormone, but that the thyroid gland can't keep up. In other words, the pituitary gland is making more requests for thyroid hormone (by producing excessive TSH) than the thyroid gland can fill.

Episodes of sudden illness can cause levels of thyroid hormone to decrease and levels of TSH to increase. This temporary condition mimics hypothyroidism. Often, running several thyroid and TSH tests over time is needed to diagnose hypothyroidism.

Treatment: Hormone supplements (eg, L-thyroxine) are given to replace the missing thyroid hormone. Older adults are usually started at a low oral dose that can be adjusted gradually over time. Older adults with heart disease are often started at an even lower dose. In rare instances, older adults with severe hypothyroidism need to receive an initial large intravenous dose of thyroid hormone.

Thyroid levels in the blood are usually checked again 6-8 weeks after the start of treatment, to see if the problem is corrected or if the dosage needs to be adjusted. Too high a dosage can lead to osteoporosis and worsen heart disease.

Thyroid hormone replacement can decrease risk of heart disease and improve mental function, although people with dementia and hypothyroidism rarely regain completely normal mental function. When someone is taking thyroid hormone, the dosages of other medications may need to be adjusted, because thyroid hormone often affects the metabolism (breakdown and elimination) of other drugs.

In hyperthyroidism, blood levels of thyroid hormone are too high. Other names for this condition include thyrotoxicosis and overactive thyroid. The most common cause in older adults is Graves' disease, which is an immune problem that stimulates the thyroid cells to produce too much hormone. Other causes include tumors of the thyroid gland that produce too much hormone, or tumors of the pituitary gland that produce too much TSH. These tumors can be benign or malignant. Hyperthyroidism that is untreated can lead to osteoporosis, heart failure, and an increased risk of heart attack.

Symptoms: The classic signs of hyperthyroidism include hyperactivity, tremor, weight loss, perspiration, a rapid and irregular heart rate, and a bug-eyed appearance. However, older adults often have signs and symptoms that are not typical. For example, older adults often have apathetic thyrotoxicosis, which is a clinical syndrome rarely seen in younger people. In this syndrome, the usual signs and symptoms of hyperthyroidism are replaced by depression, inactivity, loss of energy, muscle weakness, constipation, or withdrawn behavior. These signs are very similar to signs of hypothyroidism.

Diagnosis: Hyperthyroidism is diagnosed by finding high levels of thyroid hormone in the blood. TSH levels are also measured, because thyroid hormone levels in many older adults with hyperthyroidism are not obviously increased. Blood tests are usually repeated in 4-6 weeks to make sure that levels are consistently high. Thyroid levels can be temporarily increased by certain drugs (eg, beta-blockers or high doses of corticosteroids) or conditions (eg, fasting or hepatitis).

A specialized imaging test can be used to confirm hyperthyroidism and determine the cause (eg, cancer or Graves' disease). In this test, a small amount of radioactive iodine is given intravenously. The amount of radioactive iodine that is taken up by the thyroid provides an image of the internal structure of the thyroid gland.

Treatment: The options for treating hyperthyroidism include anti-thyroid medicines, surgery, and radioactive iodine. Drugs that slow a symptomatic, rapid, irregular heart rate (eg, a beta-blocker) may also be used. Using radioactive iodine is the simplest, least expensive, and preferred treatment. The iodine concentrates within the thyroid gland, where the radiation kills off the hyperactive tissue. Other tissues in the body are not affected, so there are no side effects that may develop with other treatments such as traditional radiation or chemotherapy (eg, hair loss, nausea, etc).

Thyroid levels usually return to normal within 6-12 weeks after radioactive iodine treatment. However, 80% of treated people eventually develop hypothyroidism, because too much thyroid tissue is destroyed. So, people treated with radioactive iodine need to have their thyroid levels checked regularly. Dosages of other medications may need to be adjusted because the body may be less able to break down certain drugs after radioactive iodine therapy.

Anti-thyroid drugs (eg, propylthiouracil) can be used to destroy circulating thyroid hormone and decrease symptoms. These drugs are often given before treatment with radioactive iodine to control symptoms and to lessen the risk of side effects. Anti-thyroid medications are not typically used long term as the only treatment for hyperthyroidism.

Nodules often develop in the thyroid gland as we age. In fact, 90% of women over 70 years old and 60% of men over 80 years old have nodules. Most of these nodules cannot be felt and often cause no symptoms. However, in some cases, these nodules can produce too much thyroid hormone or become cancerous.

The chance of getting thyroid cancer increases with age. Thyroid cancer is often a single malignant nodule. Any new nodule, or an existing nodule that gets larger, should be carefully evaluated. A few cells are often drawn out of the nodule with a needle (needle biopsy) to see if the nodule is malignant.

The most common types of thyroid cancer can usually be cured, although some types of thyroid cancer have a poorer prognosis. Thyroid cancer can be treated with radioactive iodine, surgery, or both. Radioactive iodine is often given after surgery to destroy any stray cancer cells that may have moved to other areas of the body. Drugs can be used to suppress the thyroid gland in people at high risk of developing thyroid cancer. However, side effects from long-term use of these drugs can include osteoporosis and possible heart problems.

The large amount of calcium stored in bones gives them their strength and rigid structure. Calcium in the blood is important for nerve, muscle, and kidney function. The body maintains a delicate balance between calcium in the bones and calcium in the blood. When blood levels drop too low, calcium is drawn from the bones to keep blood levels normal. When blood levels are too high, calcium goes into the bone for storage. During early life, this balancing act favors bone formation. As we age, changes in calcium regulation can lead to bone loss and osteoporosis. These age-related changes include decreased calcium intake, vitamin D deficiency, and problems with parathyroid hormone.

Calcium metabolism is controlled by parathyroid hormone, which is produced in the parathyroid gland. Parathyroid hormone is important for drawing calcium from the bone and putting it into the bloodstream. As we age, decreased calcium intake or disorders of the parathyroid gland lead to higher levels of parathyroid hormone in the blood. Blood calcium levels remain normal, but the balance between bone formation and bone loss changes in favor of loss. This results in a decrease in bone mass and an increased risk of osteoporosis.

We tend to take in less calcium as we age, because we eat fewer dairy products, we may develop lactose allergies, etc. However, the body can make up for this with more vitamin D, which improves calcium absorption from the gut. Unfortunately, vitamin D deficiency is also common in older adults. People in the hospital and nursing homes, as well as some homebound people, may get very little sun, which is needed for vitamin D production in the skin. This combination of low calcium and vitamin D deficiency leads to bone loss. Vitamin D deficiency is also linked to muscle weakness and may contribute to an increased risk of falling and breaking a bone.

Hypercalcemia is a very high level of calcium in the blood. It is often caused by disorders of the parathyroid gland that cause it to produce too much hormone. Certain cancers can also produce substances similar to parathyroid hormone. Commonly involved cancers include squamous cell cancers of the lung or head and neck, breast cancer, lymphoma, and myeloma. Symptoms of hypercalcemia can include psychiatric problems (eg, depression and loss of ability to reason), nerve problems, muscle problems (eg, weakness), and osteoporosis. However, many older adults initially have no symptoms.

Blood tests can measure levels of calcium, vitamin D, and parathyroid hormone. Other tests (eg, urine tests, x-rays, bone scans, etc) are often needed to determine the cause of the calcium disorder and to evaluate the risk of osteoporosis (see Osteoporosis). Treatment is aimed at the underlying problem.

Taking in enough calcium in the diet and vitamin D supplements can reverse age-related bone loss, increase bone mineral density, and reduce the risk of falls and fractures. For many older people, calcium intake of 1000-1500 mg per day and at least 400 IU of vitamin D per day are recommended (see Nutrition). However, too much calcium or vitamin D can lead to kidney and bone problems. You should always check with your healthcare provider before taking high-dose vitamin and mineral supplements.

Surgery is the treatment of choice for parathyroid problems that lead to hypercalcemia. Underlying cancer should also be treated. Hypercalcemia can be managed medically with intravenous fluids and diuretics (ie, "water pills"), which force calcium out with the urine. Drug treatment, such as phosphate supplements and osteoporosis drugs, may also be useful.

Blood is made up of water, cells, and various salts and minerals called electrolytes. Hormones help regulate the levels of water and electrolytes within the body. Regulation can be affected by changes related to aging, including loss of water, decreased thirst, loss of kidney function, medications, and changes in the level of antidiuretic hormone (ADH). ADH is the main hormone involved with regulation of fluid and salts. Older adults tend to have higher levels of ADH than younger people. These changes can lead to dehydration and sodium loss as we age. Older adults who are immobile or who have dementia are at the highest risk for severe dehydration.

Age-related changes in water and electrolyte regulation can also lead to high potassium levels in the blood, especially in people with diabetes or loss of kidney function. Some common drugs taken by older adults (eg, nonsteroidal anti-inflammatory drugs, ACE inhibitors, and certain types of diuretics [ie, "water pills"]) can lead to even higher levels of potassium. It is important to discuss all medication that you are taking (including over-the-counter products) with your healthcare provider.

The adrenal glands are found near the kidneys and produce several important hormones, including adrenaline, cortisol, and aldosterone. Adrenaline is involved in the stress response. Cortisol is important for proper metabolism, nutrition, and control of inflammation. Aldosterone helps regulate levels of water and salt in the body.

The adrenal gland functions through a feedback mechanism, the same as all glands that produce hormones. The adrenals shut down when cortisol levels are high, then begin producing cortisol again when levels drop.

Problems with regulation of adrenal hormones become more common as we age. For example, stressful episodes can cause a cortisol surge that is much higher and lasts longer in older adults than in younger people. Problems can develop from producing too much or not enough adrenal hormones or from adrenal cancer.

Corticosteroid drugs mimic cortisol, making the adrenals think that cortisol levels are always high. In people who are taking corticosteroid drugs (eg, prednisone) long term, the adrenals shut down and eventually are unable to start functioning again. This problem is called hypoadrenocorticism, adrenal insufficiency, or Addison's disease.

Long-term corticosteroid therapy is the most common cause of Addison's disease in older adults. Long term corticosteriods are commonly used to treat autoimmune diseases, arthritis, colitis, and organ-transplant recipients. Other common causes of Addison's disease include tuberculosis, cancer, and bleeding in the adrenal glands (eg, because of long-term treatment with blood thinners). Addison's disease can also be caused by an autoimmune process, in which the body's own immune system attacks the adrenal glands. This latter problem is the most common cause of Addison's disease in younger people but is uncommon in older adults.

Older adults with chronic Addison's disease often have general symptoms, such as loss of appetite and weight loss. High potassium levels are a more specific sign but do not show up until Addison's disease has gone on for some time.

Diagnosis and treatment: If Addison's disease is suspected, your healthcare provider will probably recommend an ACTH-stimulation test. In this test, a series of blood samples are taken before and after an injection of ACTH. ACTH is the hormone that tells the adrenal gland to produce more cortisol. When adrenal function is normal, cortisol levels increase rapidly after an ACTH injection.

Treatment for Addison's disease requires addressing the underlying problem and providing replacement therapy until adrenal function has recovered, which can take several months (if ever). Long-term corticosteroid drugs must be discontinued gradually so that the adrenal glands have time to recover. During stressful episodes (eg, surgery), higher doses of corticosteroids are needed to make up the body's demand for more cortisol.

To prevent Addison's disease, healthcare providers usually prescribe corticosteroids on an every-other-day basis, after an initial period of daily doses. This every-other-day approach allows cortisol levels to rise and fall naturally, and helps to keep the adrenals from shutting down.

In hyperadrenocorticism, cortisol levels in the body are too high. The most common cause in older adults is long-term use of corticosteroid drugs, which mimic the effects of cortisol. Cushing's syndrome can also be caused by tumors of the adrenal or pituitary gland, which cause the adrenals to produce too much cortisol. Adrenal tumors are fairly common in older adults but many are not malignant and do not lead to Cushing's syndrome.

People with Cushing's syndrome tend to build up fat in the upper body and face, giving a "moon-faced" appearance. Other signs and symptoms of Cushing's syndrome in older adults include mental symptoms (eg, reasoning difficulties), mood swings, osteoporosis, and muscle wasting.

Diagnosis and treatment: Cushing's syndrome is usually diagnosed by a blood test called the dexamethasone-suppression test. In this test, cortisol levels are measured before and after a dose of dexamethasone, which is a corticosteroid that is especially good at suppressing adrenal function. Cushing's syndrome is confirmed if cortisol levels do not drop after dexamethasone is given. Other tests, such as imaging studies (eg, CAT scan or MRI), are often needed to identify the underlying problem.

Treatment is aimed at the underlying problem. Tumors of the adrenal or pituitary glands can be corrected by surgery. Medications are also used to decrease cortisol levels (and symptoms) before surgery. Sometimes, taking corticosteroid drugs after surgery is necessary to make up for decreased natural production of cortisol.

Testosterone (in men) and estrogen (in women) are produced mainly by the primary sex organs (ie, testicles in men and ovaries in women). Sex hormones play a role in sexual activity (see also Sexual Concerns) and help to maintain overall health. In general, levels of these sex hormones decrease with age.

Testosterone levels decrease with age, so that levels are lower in healthy older men than in younger men. In fact, many otherwise healthy older men have both decreased hormone and sperm levels. Chronically ill and debilitated older men often have testosterone levels well below normal, decreased libido, decreased potency, weakness, decreased muscle mass, osteoporosis, memory loss, breast development, and hot flashes.

Other male hormones are produced by the adrenal gland. The main sex hormone produced by the adrenals is called DHEA. Levels of DHEA fall progressively with age, so that levels are 80%-90% lower in men in their 80s compared with levels in young men. Research suggests that low DHEA levels are linked to poor health, and that higher levels may be linked to longevity and improved function.

Blood tests can be used to detect low levels of male sex hormones. Men with lowered levels should also be screened for evidence of osteoporosis.

Replacement therapy is generally warranted for men with moderately decreased levels of testosterone. Such therapy may also help older men with both mildly decreased testosterone levels and general symptoms, such as weakness or decreased libido. Men should be monitored closely for adverse effects of treatment, such as worsening of prostate disease. However, there is no direct evidence that treatment with testosterone increases the risk of prostate disease, including prostate cancer.

Levels of estrogen drop considerably in women after menopause. Estrogen replacement therapy may decrease the risk of osteoporosis among postmenopausal women. Estrogen replacement can also improve some sexual disorders, such as vaginal dryness (see also Sexual Concerns).

Replacement of estrogen, with or without progesterone, was once standard care for postmenopausal women. However, this practice has fallen out of favor because of the potential for serious side effects, including increased risk of breast cancer, endometrial cancer, stroke, and deep-vein thrombosis. You should discuss estrogen replacement therapy with your healthcare provider to decide if the benefits outweigh the risks in your situation.

Growth hormones also decrease with age. In fact, about half of older adults do not produce any growth hormone by the time they are 70-80 years old. Loss of growth hormones can lead to the following:

• decreased lean body mass
• decreased muscle strength
• decreased bone density
• increased belly fat
• unfavorable lipid profiles (eg, high LDL and low HDL)
• increased risk of heart disease

Growth hormone supplements have been proved to help people with deficiency caused by diseases of the pituitary or hypothalamus gland. In these people, supplements improve lean body mass, bone density, and blood lipids. Some research studies suggest that growth hormone supplements may help other older adults as well. However, growth hormone replacement has been linked to significant side effects, including carpal tunnel syndrome, joint pain, and breast development in men. In addition, how well growth hormone supplements work and how safe they are when taken long term in older people is unknown. Growth hormone is also very expensive, and it is not currently recommended for older adults who do not have confirmed disease of the pituitary or hypothalamus gland.

Most research studies show that levels of melatonin decline throughout life, although we are not sure of any effect on health. Melatonin is thought to be involved in the regulation of daily and seasonal biorhythms. Numerous claims have been made in the lay press regarding the "anti-aging" benefits of melatonin supplements for various conditions, including insomnia, immune deficiency, cancer, and the aging process itself. Melatonin may help older people with insomnia. However, the long-term risks and benefits of melatonin supplements have not been established for insomnia or any other health problem.