High cholesterol is a condition in which you have too much low-density lipoprotein (LDL), or “bad” cholesterol, in your blood. Over time, high cholesterol levels may increase your risk of developing heart disease and related complications.

Cholesterol deposits (called plaques) in your arteries can break off and travel through your bloodstream. If one gets stuck in your heart, it can cause a heart attack. If it gets stuck in your brain, it can cause a stroke.

So, can high cholesterol also lead to pulmonary embolism (PE), a type of blood clot in your lungs? It’s hard to pin down whether there’s a direct link between high cholesterol and PE because they share many risk factors.

There’s not enough evidence to suggest that high LDL cholesterol levels increase your risk of blood clots in your veins, the type of clots that can lead to PE. But medications that help to lower LDL cholesterol levels are linked to lowering your risk of such clots.

Your risk of blood clots may actually have more to do with the level of high-density lipoprotein (HDL), or “good” cholesterol, in your blood.

This article will take a closer look at how HDL and LDL cholesterol may affect your risk of PE and the steps you can take to manage your cholesterol levels.

Important terms

To understand the research discussed in this article, it may help to become familiar with some of the following terms:

  • Arterial thrombosis: A blood clot that forms in your arteries.
  • Venous thromboembolism (VTE): A blood clot that starts in your veins.
  • Deep vein thrombosis (DVT): A subtype of VTE that starts in the deep veins of your body, typically your legs.
  • Pulmonary embolism (PE): Another subtype of VTE in which a blood clot travels through your bloodstream and blocks an artery in your lungs.
  • HDL cholesterol: This “good” cholesterol helps to remove other types of cholesterol from your blood. It’s mostly made up of a protein called apolipoprotein A1 (apoA1).
  • LDL cholesterol: The buildup of this “bad” cholesterol can lead to several heart problems. It’s mostly made up of a protein called apolipoprotein B (apoB).
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PE is a type of blood clot that blocks one or more arteries in your lungs. PE is also a subtype of VTE, with the other being DVT.

DVT is often the cause of PE. With DVT, a blood clot may occur when an issue prevents your blood from flowing properly through deep veins in your body. This can be due to blood vessel damage or issues with your blood itself.

Such a blood clot can travel to your lungs, usually from your legs, resulting in PE. This can happen after:

  • not moving for long periods (e.g., prolonged travel, bed rest)
  • injury
  • infection
  • systemic inflammation due to illness
  • surgery
  • trauma

There are two main types of blood clots. We’ve already discussed VTE, which starts in your veins and can lead to DVT or PE.

There’s also arterial thrombosis, which are clots that start in your arteries. While these clots don’t cause DVT or PE, they can increase your risk of heart attack or stroke.

High blood cholesterol may contribute to arterial thrombosis. These clots are often associated with peripheral artery disease (PAD).

Like DVT, PAD usually develops in your lower extremities, such as your legs. Unlike DVT, PAD is most often due to atherosclerosis, or the buildup of plaque in your arteries. Other risk factors for PAD include:

High cholesterol doesn’t directly cause DVT blood clots. These clots differ from clots found in your arteries in several ways.

PAD clots are typically rich in platelets, blood cells that help your blood clot. While platelets are involved in DVT clots, they don’t play as big a role. DVT clots are usually rich in red blood cells and a protein called fibrin.

PAD blood clots typically develop around plaque in your arteries. DVT clots can develop on the walls of blood vessels that don’t have plaque.

Even though these two types of clots develop in different blood vessels and have different structures, they share similar risk factors.

So, yes, high cholesterol can cause blood clots. But they’re not the clots that typically lead to VTE, including PE.

High cholesterol (hypercholesterolemia) is when your LDL cholesterol level is higher than 190 mg/dL. A doctor may also diagnose you with hypercholesterolemia if you have LDL cholesterol levels as low as 130 mg/dL but also have one or more important risk factors. One such risk factor is having low HDL cholesterol levels.

Let’s look at how LDL and HDL affect your risk of VTE.

LDL cholesterol and VTE

Studies exploring a link between LDL cholesterol levels and VTE have produced conflicting results.

A 2017 study in the Netherlands found that LDL levels weren’t associated with VTE risk. The study actually found that decreased levels of ApoB (the main protein in LDL cholesterol) were linked to higher VTE risk. A 2019 British study also found that low ApoB led to higher VTE risk.

But a different 2019 study found that high LDL levels may be a causal risk factor for VTE. The study found that VTE risk was lower in people who took statins, medications that lower LDL cholesterol. However, some research suggests that this benefit is due to a different mechanism, and not because the medications lower LDL cholesterol levels.

PCSK9 inhibitors, which also lower LDL cholesterol, may also lower your risk of VTE. The 2020 study found that this was likely tied to a decrease in lipoprotein(a), specifically. Lipoprotein(a) is a type of LDL.

According to some research, LDL may also cause excess platelet activity. High LDL levels in people with hyperlipidemia may be linked to blood clots. While platelets are more linked to arterial clots, some research is looking into possible linkage to VTE.

HDL cholesterol and VTE

Some studies suggest that there may be a link between low levels of HDL cholesterol and an increased risk of VTE. A 2020 study found that low levels of proteins associated with HDL, such as ApoA1, were linked to an increased risk of DVT in humans.

A 2019 study didn’t find a link between low HDL and VTE, but it did find that lower ApoA1 was linked to a greater risk of VTE. The 2017 Dutch study previously cited also found a link between lower ApoA1 and higher VTE risk. Researchers believe that ApoA1 may have anticlotting properties.

High levels of LDL cholesterol are more likely to cause blood clots in your peripheral arteries. They’re less likely to cause blood clots in your veins, which lead to DVT or PE. But that doesn’t mean it can’t happen.

Low levels of HDL cholesterol may put you at greater risk of PE. A small 2016 study found that HDL levels in people with PE were significantly lower than in people without PE.

Additionally, one clinical trial suggests that people with a history of acute coronary syndrome (a type of blockage that can lead to a heart attack) may be at an increased risk of developing both PAD and VTE.

Still, more research is needed to confirm whether there’s a direct connection between high LDL cholesterol levels and the development of DVT and PE.

Possible symptoms of PE include:

However, experts estimate that half of people with PE are asymptomatic.

Pulmonary embolism is a medical emergency

If you have symptoms of a possible PE, you should call 911 or local emergency services immediately. This sudden blockage in your lungs may quickly lead to low blood oxygen, permanent lung damage, and damage to other lungs throughout the body.

Due to such effects, PE can be life threatening. The risk of PE-related death may be greater if you have a large blood clot or multiple blood clots in the lungs.

With PE, the goal of emergency medical care is to help break up the clot(s) in your lungs. You’ll also be prescribed medication to prevent future clots from forming.

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While anyone may develop PE, certain risk factors can increase your risk. These include:

  • Age: Your risk of PE increases after the age of 40.
  • Family history: Having relatives with VTE may increase your risk of developing PE and other types of blood clots.
  • Obesity: This condition may weaken your blood vessels, increasing your risk of blood clots such as PE.
  • Other medical conditions: These include heart and lung diseases, cancers, and recent injuries or traumas.
  • Recent surgery: This is especially true for surgeries that involve the lower half of your body, such as hip replacement surgery.
  • Certain hormone medications: These include oral contraceptives (birth control) and hormone replacement therapies used during and after menopause.
  • Pregnancy and childbirth: Your risk may be greater within the 6 weeks after delivery.
  • Extended bed rest: Not moving for long periods due to an illness, recent surgery, or traveling may decrease blood flow and increase your risk of blood clots.

Certain lifestyle changes can help you manage high cholesterol and lower your risk of developing blood clots. These include:

However, if your blood cholesterol is still high despite making changes, a doctor may recommend cholesterol-lowering medications. As mentioned above, some of these medications may lower your VTE risk.

Losing weight may also help. According to the American Heart Association, losing 5% to 10% of your body weight may lower LDL cholesterol.

You can help lower your risk of blood clots more specifically by:

  • wearing compression stockings to help prevent DVT
  • moving around frequently when traveling
  • avoiding prolonged bed rest, or getting up as often and as soon as you can

You can also help lower your risk of developing PE by taking any medications as prescribed, including blood thinners.

Comorbidities of high cholesterol

High cholesterol and PE share similar risk factors. They include having overweight or obesity and not exercising regularly. If you’re concerned about weight loss or being unable to move for long periods, it’s important to talk with a doctor for solutions.

Other comorbidities of high cholesterol may include:

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High cholesterol can lead to blood clots in your arteries but doesn’t often lead to blood clots in your veins. PEs develop from blood clots in your veins, so high cholesterol doesn’t usually lead to PE.

However, high cholesterol and PE may develop from similar risk factors, such as a lack of physical activity and genetics. It’s possible they may co-exist.

Experts don’t yet know if a direct link causes high cholesterol to increase your risk of PE, but medications that lower your LDL (“bad”) cholesterol levels seem to lower your risk of PE. High HDL (“good”) cholesterol levels may also lower your risk.

If you have risk factors for either high cholesterol or PE, you should speak with a doctor for possible diagnosis and treatment. The steps you take to manage your cholesterol levels can improve your heart health and lower your risk of several possible complications.