Familial Hypertriglyceridemia

Familial hypertriglyceridemia is a genetic disorder that causes elevated levels of fats in your blood, increasing your risk of heart disease and, in severe cases, a serious condition affecting your pancreas.

type IV familial dyslipidemia, type IV hyperlipoproteinemia

Table of contents

• What Is Familial Hypertriglyceridemia?
• Causes and Inheritance Pattern
• How the Body Is Affected
• Signs and Symptoms
• Diagnosis and Testing
• Treatment and Management
• Possible Complications
• Prevention and Early Detection

What Is Familial Hypertriglyceridemia?

Familial hypertriglyceridemia is a common genetic disorder passed down through families that causes higher-than-normal levels of triglycerides (a type of fat) in a person’s blood^[1]. Triglycerides are fats that provide energy to your body. You get some from foods you eat, and when you consume more calories than you need, your body converts them into triglycerides for later use^[2].

This condition is characterized by the liver producing too much of a substance called very low-density lipoprotein (VLDL), which carries triglycerides through your bloodstream^[1]. When these levels become too high, they can increase your risk of heart disease and other serious health problems.

A normal triglyceride level in adults is below 150 milligrams per deciliter (mg/dL) when measured after fasting. In familial hypertriglyceridemia, blood tests typically show mild to moderate increases in triglycerides, usually in the range of about 200 to 500 mg/dL^[2]. However, when combined with other conditions or certain medications, triglyceride levels can rise much higher, sometimes reaching levels that require immediate attention.

Causes and Inheritance Pattern

Familial hypertriglyceridemia is most likely caused by genetic changes combined with environmental factors. As a result, the condition tends to cluster in families^[2]. This condition typically follows an autosomal dominant inheritance pattern, which means affected individuals have a 50% chance of passing the disorder to their children^[1].

However, recent evidence suggests that most cases have a polygenic basis, meaning multiple genes contribute to the condition rather than a single gene causing the disease^[1]. This distances the condition from traditional patterns of inheritance and helps explain why the severity can vary so much between family members.

One of the most common genetic changes involves a gene that codes for an enzyme called lipoprotein lipase (LPL). This enzyme normally breaks down triglycerides in the bloodstream. When the LPL gene is affected, the enzyme doesn’t work properly, leading to a buildup of triglycerides and VLDL in the blood^[3].

Several factors can make familial hypertriglyceridemia worse. These include obesity, high blood sugar levels (hyperglycemia), high insulin levels, alcohol consumption, a diet high in carbohydrates, and use of estrogen-containing medications such as certain birth control pills^[2]. The severity of the disorder can also vary based on sex, age, hormone use, and dietary factors.

How the Body Is Affected

In familial hypertriglyceridemia, the lack of proper lipoprotein lipase activity plays the main role in how the condition affects your body. This enzyme is responsible for breaking down triglycerides within VLDL molecules. When it doesn’t work properly, VLDL molecules and triglycerides build up in the bloodstream^[3].

People with this condition also have high levels of VLDL in their blood. At the same time, their levels of LDL cholesterol (often called “bad” cholesterol) and HDL cholesterol (often called “good” cholesterol) are often low^[2]. This combination of high triglycerides with low HDL cholesterol is particularly concerning for heart health.

In most cases, familial hypertriglyceridemia is not noticeable until puberty or early adulthood. Conditions that often occur alongside familial hypertriglyceridemia include obesity, high blood sugar levels, and high insulin levels. These co-existing conditions can push triglyceride levels even higher^[2].

Insulin, a hormone that helps control blood sugar, is also a powerful activator of lipoprotein lipase. Therefore, someone who is resistant to insulin will have decreased LPL activity, leading to even higher triglyceride levels and pushing them toward dangerous levels^[3].

Signs and Symptoms

Most people with familial hypertriglyceridemia have no symptoms at all. Many individuals may be asymptomatic until severe complications develop^[1]. Some people with the condition may develop coronary artery disease at an early age^[2].

When triglyceride levels become very high (500 mg/dL or higher), some people may develop visible signs. These include xanthomas, which are fatty deposits that appear as bumps under the skin, particularly on the elbows, knees, hands, or buttocks^[1]. People with severely elevated levels may also develop an enlarged liver (hepatomegaly) or a condition called lipemia retinalis, where the blood vessels in the back of the eye appear pale or milky white^[1].

You are more likely to have this condition if you have a family history of high triglycerides or heart disease before age 50^[2]. Early identification is important because recognizing clinical signs such as xanthomas, hepatomegaly, and lipemia retinalis, along with obtaining a thorough family medical history, aids in timely diagnosis^[1].

Diagnosis and Testing

Your healthcare provider will perform a physical exam and ask about your family history and symptoms. If you have a family history of this condition, you should have blood tests to check VLDL and triglyceride levels^[2].

A blood test to measure triglyceride levels is usually conducted after fasting, meaning no food except water for 8 to 12 hours before the blood sample is collected. Blood tests in people with familial hypertriglyceridemia most often show a mild to moderate increase in triglycerides, about 200 to 500 mg/dL^[2].

A coronary risk profile may also be done to assess your overall risk of heart disease. The physical exam will check for fat deposits under the skin and signs of other medical conditions associated with high triglycerides^[2].

It’s important to talk to your parents or family members about your family’s medical history. Ask whether anyone in your family had high triglycerides, was diagnosed with heart disease before age 50, or had a heart attack or stroke before age 50. Tell your doctor the answers to these questions, as this information could hold clues about your chances of having an inherited disorder^[16].

Treatment and Management

Effective management of familial hypertriglyceridemia requires a comprehensive approach that combines lifestyle changes and, when necessary, medication. The goal of treatment is to control conditions that can raise triglyceride levels and to reduce your risk of complications affecting your heart or pancreas^[2].

Lifestyle changes are the foundation of treatment. If you’re overweight, losing even a modest amount of weight can make a significant difference. Aim for at least 30 minutes of exercise on most days of the week. Your provider may tell you not to drink alcohol, as alcohol can significantly raise triglyceride levels. In some people, even small amounts of alcohol may cause triglyceride levels to rise^[2].

Dietary changes are crucial. Treatment involves avoiding excess calories and foods high in saturated fats and carbohydrates. Cutting back on sugar in desserts, drinks, and other foods is important. Instead, eat more fruits, vegetables, whole grains, and foods containing omega-3 fatty acids, which are healthy fats found in certain fish including salmon, herring, albacore tuna, and sardines. Plant sources include walnuts and flaxseed^[16].

Certain medications can affect triglyceride levels. Some birth control pills can raise triglyceride levels, so talk to your provider about your risk when deciding whether to take these medicines^[2]. If you have other conditions such as diabetes or thyroid problems, treating these conditions effectively can help improve your triglyceride levels.

If lifestyle changes don’t lower your triglyceride levels enough, you may need to take medicine. Several medications can lower triglyceride levels in people with this condition, including nicotinic acid (niacin), gemfibrozil, and fenofibrate^[2]. Your doctor will select appropriate medications and adjust dosages based on your specific situation and response to therapy^[1].

For people with very high triglyceride levels (500 mg/dL or higher), medications called fibrates and omega-3 fatty acids may be prescribed to reduce the risk of a serious complication called pancreatitis^[8]. Even with medication, you’ll still need to keep up with diet and exercise to manage your triglyceride levels.

Possible Complications

Familial hypertriglyceridemia increases the risk of atherosclerotic cardiovascular disease (ASCVD), which includes heart disease and stroke^[1]. Elevated triglyceride levels, especially when combined with low HDL cholesterol and high LDL cholesterol, significantly raise your risk of developing these conditions.

The most serious acute complication is pancreatitis, which is inflammation of the pancreas. This risk increases substantially when triglyceride levels reach 500 mg/dL or higher, and becomes even more significant at levels of 1,000 mg/dL or higher^[8]. Pancreatitis is caused by premature activation of digestive enzymes in the pancreas. It presents as severe abdominal pain, nausea, and vomiting, and requires immediate medical care^[3].

Possible complications may include pancreatitis and coronary artery disease^[2]. However, losing weight and keeping conditions like diabetes under control helps improve the outcome and reduce these risks.

Prevention and Early Detection

Since familial hypertriglyceridemia is an inherited condition, you cannot prevent the genetic tendency itself. However, you can take steps to prevent triglyceride levels from rising to dangerous levels and reduce your risk of complications.

Screening family members for high triglycerides may detect the disease early^[2]. If familial hypertriglyceridemia runs in your family, talk to your doctor about when you and your family members should be tested. Early identification and intervention are crucial, as individuals may be asymptomatic until severe complications arise^[1].

Maintaining a healthy lifestyle from an early age can help keep triglyceride levels in check. This includes maintaining a healthy weight, staying physically active, eating a heart-healthy diet low in saturated fats and refined carbohydrates, limiting or avoiding alcohol, and not smoking.

If you have familial hypertriglyceridemia, regular monitoring of your triglyceride levels is important. Work closely with your healthcare team to develop a personalized treatment plan. With proper management through lifestyle changes and medication when needed, most people with familial hypertriglyceridemia can keep their triglyceride levels under control and significantly reduce their risk of serious complications^[1].