What You Need to Know About Cholesterol When You Have Hypothyroidism

Fatigue. Weakness. Weight gain. Anxiety and depression. When you have hypothyroidism — an underactive thyroid gland — you may have to deal with all these symptoms.

You also might be living with high cholesterol, which can lead to heart disease over time.

“Untreated hypothyroidism has been shown to be associated with increased cardiovascular mortality and morbidity,” says Elizabeth A. McAninch, MD, a clinical associate professor of endocrinology, gerontology, and metabolism at Stanford Medicine in Stanford, California. “That’s one of the reasons that the American Thyroid Association [ATA] guidelines recommend treating patients with overt hypothyroidism.”

But why does hypothyroidism cause high cholesterol? What does your thyroid have to do with your heart? And more importantly, what can you do about it?

Your thyroid is an endocrine gland, shaped like a butterfly or bow tie, at the front of your throat. It controls your metabolism — how your body uses energy — by releasing hormones. These hormones play various roles in many important body processes, including:

• Bone formation and resorption
• Brain development
• Digestion
• Heart function
• Motor control

If your thyroid doesn’t produce enough hormones, you might experience:

• Constipation
• Depression
• Dry hair and skin
• Fatigue
• A goiter (swollen thyroid gland)
• Sensitivity to the cold
• Slowed heart rate
• Weight gain

The two main types of cholesterol are LDL, the “bad kind” since it collects in the walls of blood vessels when there’s too much of it (think “L” for “lousy”), and HDL, the “good kind” since it helps remove extra cholesterol from your bloodstream (“H” for “helpful”). There are also blood fats called triglycerides that are not cholesterol but often measured with it.

High cholesterol usually doesn’t have symptoms, but it can put you at risk for a heart attack and stroke. You want to aim for LDL under 100 mg/dL and HDL over 40 mg/dL to stay at healthy levels.

One of the hormones your thyroid produces — thyroxine (T4) — has direct effects on cholesterol; your body needs T4 to break cholesterol down. If your thyroid doesn’t produce enough T4, your body can’t clear cholesterol from your bloodstream fast enough to prevent it from turning into plaque.

Another thyroid-related hormone may influence cholesterol levels as well. When your thyroid isn’t making enough T4, your pituitary — a pea-size gland located at the base of the brain — makes thyroid-stimulating hormones (TSH) to tell your thyroid to get to work.

It’s important to keep your cholesterol at healthy levels whether you have an underactive thyroid or not. HDL carries LDL to the liver, which breaks it down and removes it from your body. Excess LDL can stick to your arteries, and cholesterol and triglyceride buildup on the artery walls — plaque — makes the artery narrower, causing higher blood pressure. This plaque may also break open, leading to red blood cells rushing to repair the damage and forming a clot.

Blood clots can break off artery walls and be carried away by the bloodstream — unless the clot gets stuck. If a clot gets stuck and prevents nourishing blood from reaching the heart or brain, tissue starts to die. This means you’re having a heart attack or a stroke, depending on which organ is being deprived of blood.

Treating hypothyroidism with synthetic hormones may help lower cholesterol levels, according to the ATA. But it’s possible that standard treatment alone isn’t enough to keep all systems running normally.

So, although levothyroxine works well for raising levels of thyroid hormone production (despite not being a treatment for high cholesterol), it may not be enough to adequately lower your cholesterol. You might need to add cholesterol-lowering medication, make lifestyle changes, or both.

Medication

Lifestyle Changes

Lifestyle changes can help lower your cholesterol levels, regardless of whether you have hypothyroidism.

Improve your diet. A heart-healthy diet rich in fruits and vegetables, whole grains, and lean proteins like poultry, fish, and nuts — as well as low in saturated and trans fats — can have a big effect on your cholesterol levels. Think “Mediterranean diet” and you’ll be most of the way there.

Remember to take it slow, especially if you’re trying to drastically change your eating patterns. “It can be daunting to go from a very unhealthy diet to a [healthy] diet, so I try to just make one or two suggestions to start,” says McAninch.

• Hypothyroidism is an underactive thyroid, while high cholesterol is an excess of this waxy, fatty substance building up in your arteries.
• Low thyroid hormone levels and high thyroid-stimulating hormone levels frequently mean increased cholesterol, which can put you at higher risk for a stroke or heart attack.
• The main medical treatments for hypothyroidism (levothyroxine) and high cholesterol (statins) can be effective for people with both conditions, as are healthy lifestyle habits such as exercising more and eating lean meats, fruits, vegetables, and healthy fats. It’s important to note you’re more likely to be intolerant of statins if you have hypothyroidism, and especially if you’re female.