Why is cholesterol dangerous?
Your doctor has probably cautioned you about cholesterol, the fatty, waxy substance that circulates in your blood. Too much of the wrong type of cholesterol can clog your arteries and put you at risk of heart disease.
High cholesterol levels can stem from your diet, especially if you eat foods high in saturated fats, like red meat and butter. Sometimes though, your thyroid gland may be to blame. Too much or too little thyroid hormone can make your cholesterol levels swing up or down. Here’s a look at how your thyroid affects cholesterol.
What is the thyroid gland?
Your thyroid is a butterfly-shaped gland in your neck. It produces hormones that control metabolism. Metabolism is the process your body uses to convert food and oxygen into energy. Thyroid hormones also help the heart, brain, and other organs to work normally.
The pituitary gland is located at the base of the brain and directs the thyroid’s activities. When your pituitary senses that you’re low in thyroid hormone, it releases thyroid-stimulating hormone (TSH). TSH directs the thyroid gland to release more hormones.
HDL and LDL Cholesterol
Cholesterol is contained in each of your body’s cells. Cholesterol circulates through your blood called lipoproteins. It travels in the bloodstream in 2 types of packages.
- High-density lipoprotein (HDL) cholesterol is good for your heart. It helps remove cholesterol from your body and protects against heart disease.
- Low-density lipoprotein (LDL) cholesterol is bad for your heart. If LDL cholesterol levels are too high, the cholesterol can clog arteries and contribute to heart disease, heart attack, and stroke.
Underactive or Overactive Thyroid
The thyroid can produce too little or too many hormones.
A condition in which your thyroid is underactive is called hypothyroidism. When the thyroid is underactive, your whole body feels like it’s slowing down. You become tired, sluggish, cold, and achy.
You might get an underactive thyroid if you have the following conditions:
- Hashimoto’s thyroiditis
- Thyroid inflammation (thyroiditis)
Other factors that can result in an underactive thyroid include:
- removal of all or part of an overactive thyroid
- radiation treatments for the thyroid
- certain medications, such as lithium, interferon alpha, and interleukin 2
- damage to the pituitary gland from a tumor, radiation, or surgery
Hyperthyroidism is a condition that occurs when you have an overactive thyroid. When your thyroid is overactive, your body kicks into fast gear. Your heart rate speeds up, and you feel nervous and shaky.
You might get hyperthyroidism if you have:
- Thyroid inflammation
- Graves’ disease, an immune system disorder that runs in families
- toxic nodular goiter, which involves lumps or nodules on the thyroid
How does the thyroid cause cholesterol problems?
Your body needs thyroid hormones to make cholesterol and to get rid of the cholesterol it doesn’t need. When thyroid hormone levels are low (hypothyroidism), your body doesn’t break down and remove LDL cholesterol as efficiently as usual. LDL cholesterol can then build up in your blood.
Thyroid hormone levels don’t have to be very low to increase cholesterol. Even people with mildly low thyroid levels, called subclinical hypothyroidism, can have higher than normal LDL cholesterol. A 2012 study found that high TSH levels alone can directly raise cholesterol levels, even if thyroid hormone levels aren’t low.
Hyperthyroidism has the opposite effect on cholesterol. It causes cholesterol levels to drop to abnormally low levels.
What are the symptoms?
You might have an underactive thyroid gland if you notice these symptoms:
- weight gain
- slow heartbeat
- increased sensitivity to cold
- muscle aches and weakness
- dry skin
- trouble remembering or focusing
An overactive thyroid has almost the exact opposite symptoms:
- weight loss
- fast heartbeat
- increased sensitivity to heat
- increased appetite
- more frequent bowel movements
- trouble sleeping
Getting Your Thyroid and Cholesterol Tested
If you have symptoms of a thyroid problem and your cholesterol levels are high or low, see your doctor. You’ll get blood tests to measure your level of TSH and your level of a thyroid hormone to determine if your thyroid is overactive or underactive.
When your thyroid hormone level is just marginally low, you may not need thyroid hormone replacement. Instead, your doctor might put you on a statin or other cholesterol-lowering drug.
For an overactive thyroid, your doctor will give you radioactive iodine to shrink the gland or medicines to reduce thyroid hormone production. A small number of people who can’t take antithyroid drugs may need surgery to remove most of the thyroid gland.