The thyroid gland affects the function of every organ in your body, including your heart. The thyroid — a butterfly-shaped structure located in the base of your throat — releases hormones that affect heart rate and blood pressure, and too little or too much of these hormones is associated with heart disease.
The cardiovascular signs and symptoms of thyroid disease are often noticeable to the patient and accompany both an overactive and underactive thyroid. It’s important to recognize that these effects on the heart are often reversible with medical treatment to restore normal thyroid function.
Who’s at risk for thyroid problems?
The following factors increase your likelihood of having a thyroid problem:
1. Age: The prevalence of an underactive thyroid increases with age, especially after the age of 60.
2. Gender: Women are five to eight times more likely to have thyroid problems as compared to men.
3. Family history: People with parents or siblings who have underactive or overactive thyroids have a higher likelihood of developing thyroid disease.
4. Race/ethnicity: Caucasians have higher rates of underactive thyroids than Hispanic-Americans and African-Americans.
5. Health history: Thyroid problems are more likely among people with a personal or family history of certain conditions, including diabetes, autoimmune diseases such as rheumatoid arthritis and lupus, vitamin B12 deficiency, pregnancy, premature gray hair and radiation treatments to the head and neck.
[See: 11 Strategies for Keeping Your Health Data Secure.]
What is hypothyroidism?
Hypothyroidism occurs when an underperforming thyroid gland doesn’t make enough thyroid hormone. Physicians diagnose the condition by measuring the levels of thyroid stimulating hormone (TSH), thyroxine (T4) and triidothyroxine (T3) in the blood. In people with hypothyroidism, the TSH level is usually elevated and the T4 level is low. When thyroid hormone levels drop, all the systems in the body slow down. This triggers a response that leads to fatigue, weight gain, cold intolerance, constipation and dry skin. But these symptoms are also very commonly seen in people as they grow older, including those with normal thyroid levels. Because some people over age 60 with low thyroid levels don’t have the classic symptoms, they often go undiagnosed. That’s why recognizing thyroid abnormalities can be tricky.
Some other common symptoms of hypothyroidism include fatigue, slow pulse, irregular periods, hair loss, thick doughy skin, hoarseness, muscle and joint pain, poor reflexes and erectile dysfunction.
How does hypothyroidism impact the cardiovascular system?
According to the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases’ 2012 data, nearly 5 percent of people in the U.S. over age 12 have hypothyroidism — that’s more than 9.5 million people . Five large studies with over a million participants linked hypothyroidism to heart disease, heart attacks and heart-related death. Even patients with no overt signs of hypothyroidism but a high TSH level were also more prone to heart disease and dying from heart-related issues.
Low thyroid hormone levels change the arteries by making them less elastic; to compensate, the blood pressure rises in order to circulate blood around the body. Patients with hypothyroidism often have high blood pressure as a result. Long-term hypothyroidism can cause changes in the body’s metabolism and produce high blood lipid (fats) levels, such as high total cholesterol, “bad” cholesterol and triglycerides. These elevated lipid levels in turn contribute to narrowed and hardened arteries, increasing the plaque buildup inside the heart’s arteries.
Muscle aches are also a sign of hypothyroidism. Coincidently, achy muscles are also a side effect of cholesterol-lowing statins, and the muscle aches from hypothyroidism are often misdiagnosed as a side effect of the medication. In severe prolonged hypothyroidism, the heart muscle fibers may become diseased and lead to a weakened heart. Hypothyroidism can lead to impaired pumping and relaxation functions of the heart, which can reduce exercise tolerance and increase fatigue during physical activity. Oftentimes, fluid collects around the heart, but it rarely produces any symptoms. However, in extreme cases, the fluid can accumulate over time and compress the heart, compromising the pumping ability and causing death.
[See: 10 Signs Your Thyroid Is Out of Whack.]
What is subclinical hypothyroidism and its impact on the heart?
Subclinical hypothyroidism is a common disorder that is characterized by elevated TSH levels in individuals with normal T4 levels. These patients often have none of the hypothyroidism symptoms mentioned above, or they may have mild symptoms. They may have fatigue, cold intolerance or depression. There’s a strong link between subclinical hypothyroidism and cardiovascular disease risk factors such as abdominal obesity, diabetes, high blood lipid levels and high blood pressure. These disorders together are called metabolic syndrome.
What is hyperthyroidism?
Hyperthyroidism, or too much thyroid hormone, is a far less common condition, affecting less than 1 percent of people. It’s usually diagnosed by low levels of TSH and high levels of T4 and T3. Hyperthyroidism can be due to Grave’s disease, which is an inflammation of the thyroid caused by the body’s immune system that causes the gland to swell; toxic multinodular goiter, which is a swollen thyroid secreting large amount of thyroid hormones; or by nodules in the pituitary gland, which is a small structure in the brain that makes TSH and other hormones. People with hyperthyroidism may experience irritability, muscle weakness, sleeping problems, a fast heartbeat, poor heat tolerance, diarrhea, unintentional weight loss, skin problems and eye swelling.
How does hyperthyroidism impact the cardiovascular system?
People with hyperthyroidism can experience specific heart-related symptoms including palpitations, exercise intolerance, shortness of breath, chest pain, swelling in the legs and congestive heart failure. Increased levels of T4 stimulate the heart to beat more quickly and more strongly, producing a fast heart rate. Typically this fast heart rate is caused by stimulation of the heart’s normal pacemaker. But the fast heart rate can also be caused by atrial fibrillation, an irregular heart rhythm that can occur in an estimated 10 to 25 percent of all symptomatic hyperthyroid patients and is the most common cardiac complication of hyperthyroidism. It’s important to identify atrial fibrillation because it’s associated with increased stroke risk and other heart problems. Health care providers can detect atrial fibrillation even if it isn’t noticed by the patient just by checking the patient’s pulse.
If the fast heart rate becomes severe then the patient may notice palpitations, or awareness of one’s heartbeat. Usually, palpitations are one of the first symptoms patients experience, leading them to seek out a cardiologist. The cardiologist will perform an electrocardiogram to diagnose the type of fast heartbeat.
Hyperthyroidism can also affect blood pressure and heart function over time. Prolonged stimulation of heart contraction, as with fast heartbeat, can cause an increase in the top number of your blood pressure reading. The increased contraction of the heart with increased blood pumping causes a pulse that is easily felt at the wrist and contributes to warm sweaty hands. Overstimulation of the heart muscle over time can lead to weakness and cause heart failure or cardiomyopathy as well.
What can you do?
Request a test:
— If you’re at risk of (or already have) heart disease and have symptoms of hypothyroidism or hyperthyroidism, ask your primary care provider or cardiologist to consider testing your thyroid.
— It’s important to work with your doctor to manage your blood pressure, blood sugar and lipids to prevent heart disease from developing or progressing.
— If you have cardiac complications from thyroid disease then you will need to follow up with your cardiologist often.
— Most cardiologists will order heart-specific tests such as ECGs and ultrasounds of your heart (echocardiograms) to assess your heart rhythm and function. In some cases, cardiac CT scans could be considered to look for evidence of plaque buildup in the coronary arteries.
Treatment:
Hypothyroidism is treated by replacing the active thyroid hormone, T4 — the hormone that your own thyroid no longer makes. Most doctors will prescribe levothyroxine, a thyroid hormone medicine that is identical to T4. Your doctor will give you a blood test in about 6 to 8 weeks after taking the medicine and adjust your dose if needed.
For hyperthyroidism, the course of treatment uses drugs that block T4 and T3 production, radioactive iodine therapy or thyroid surgery, depending on the nature of the thyroid problem. If patients have chest pains or atrial fibrillation, then the physician may prescribe a drug that slows the heart rate, such as a beta-blocker (e.g., propranolol or metoprolol). Patients with heart failure are usually treated in the standard way with heart medications to improve heart function, such as ACE-inhibitors (e.g., lisinopril, ramipril), beta-blockers and diuretics, drugs that increase excretion of water by the kidneys (e.g., furosemide).
[See: The Best Foods for Lowering Your Blood Pressure.]
Take-home points:
— Hyperthyroidism and hypothyroidism can both negatively affect the cardiovascular system.
— Hypothyroidism is linked with plaque buildup in the heart’s arteries, high lipid levels, fluid around the heart, damage to the heart muscle and metabolic syndrome.
— Hyperthyroidism can lead to heart failure, high blood pressure and an irregular heartbeat.
— Early diagnosis and treatment of thyroid disease can reverse the cardiovascular-damaging side effects.
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Can Your Thyroid Affect Your Heart? originally appeared on usnews.com
