Lipid Metabolism Disorder

When your body cannot properly process fats, harmful amounts can build up, potentially damaging vital organs and increasing your risk of serious health complications.

Table of contents

• What Are Lipids and How Does Your Body Use Them?
• Understanding Lipid Metabolism Disorders
• Types of Lipid Metabolism Disorders
• What Causes These Disorders
• Parts of the Body That Can Be Affected
• How These Disorders Are Diagnosed
• Treatment Options
• Possible Complications

What Are Lipids and How Does Your Body Use Them?

Lipids are fats or fat-like substances found throughout your body. They include oils, fatty acids, waxes, and cholesterol^[1]. Your body needs lipids for many important functions. They help build the walls of your cells, store energy for later use, keep your body temperature stable, and work as chemical messengers^[2].

Metabolism is the process your body uses to make energy from the food you eat. When you eat food that contains proteins, carbohydrates, and fats, chemicals in your digestive system called enzymes break these food parts down into sugars and acids that your body can use as fuel. Your body can use this fuel right away or store the energy in your tissues for later^[1].

Understanding Lipid Metabolism Disorders

If you have a metabolic disorder, something goes wrong with this normal process. In lipid metabolism disorders, your body may not have enough enzymes to break down lipids. Or the enzymes may not work properly, so your body cannot convert the fats into energy^[1].

When lipids cannot be broken down properly, they cause a harmful amount of lipids to build up in your body. The enzymes needed to metabolize lipids may not work properly or are not produced in sufficient amounts. Excessive lipids are then stored, which causes permanent cellular and tissue damage^[2].

Over time, this buildup can damage your cells and tissues. The damage is especially serious in certain parts of the body, including the brain, peripheral nervous system (the nerves outside your brain and spinal cord), liver, spleen, and bone marrow^[1].

• Brain
• Peripheral nervous system
• Liver
• Spleen
• Bone marrow
• Heart

Types of Lipid Metabolism Disorders

There are many different types of lipid metabolism disorders. Some well-known examples include Gaucher disease and Tay-Sachs disease^[1].

Lipid storage diseases, also known as lipidoses, are a group of inherited metabolic disorders where harmful amounts of fatty materials build up in various cells and tissues in the body. This happens because people with these disorders cannot make enough of the enzymes needed to break down lipids, or they make enzymes that do not work properly^[4].

One type of lipid storage disease is Niemann-Pick disease Type C, which occurs in people who cannot properly break down cholesterol and other lipids. This leads to too much cholesterol in the liver and spleen and too much of other lipids in the brain^[4].

Other rare disorders of lipid metabolism include cerebrotendinous xanthomatosis, where a product of cholesterol metabolism called cholestanol accumulates in tissues. This disease eventually leads to uncoordinated movements, dementia, cataracts, early coronary artery disease, and fatty growths on tendons. The disabling symptoms often appear during adolescence^[5].

Sitosterolemia is another disorder where plant fats accumulate in blood and tissues. These fats are found in many foods such as nuts, vegetable oils, and chocolates. The buildup of fats leads to atherosclerosis, early coronary artery disease, abnormal red blood cells, and fatty growths on tendons^[5].

What Causes These Disorders

These disorders are inherited, meaning they are passed down from parents to their children through genes^[1]. In many cases, both parents of the affected child carry one copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder^[5].

Abnormal levels of blood lipids can also be caused by other factors. Causes for high lipid levels include diabetes, alcoholism, kidney disease, hypothyroidism, liver disease, and stress. When lipids build up, they can easily adhere to the walls of blood vessels, and the growing fatty deposits can cause a variety of disorders related to blocked arteries^[2].

Parts of the Body That Can Be Affected

Storing too many lipids inside cells can cause permanent damage to cells and tissues, especially in the brain, peripheral nervous system, liver, spleen, heart, and bone marrow^[4].

Lipids are fat-like substances in the membranes found within and between cells and in the myelin sheath that coats and protects the nerves. Tiny structures within cells called lysosomes regularly convert, or metabolize, the lipids and proteins into smaller components to provide energy for the body^[4].

How These Disorders Are Diagnosed

Newborn babies get screened for some of these disorders using blood tests. If there is a family history of one of these disorders, parents can get genetic testing to see whether they carry the gene. Other genetic tests can tell whether the fetus has the disorder or carries the gene for the disorder^[1].

Before birth, doctors can diagnose some lipid metabolism disorders by doing prenatal screening tests like amniocentesis or chorionic villus sampling. After birth, some lipid metabolism disorders are identified through routine newborn screening tests or other diagnostic procedures^[5].

Treatment Options

Enzyme replacement therapies can help with a few of these disorders. For others, there is no specific treatment. Medicines, blood transfusions, and other procedures may help with complications that arise from these conditions^[1].

Treatment varies depending on the specific disorder. For cerebrotendinous xanthomatosis, if started early, the medication chenodiol (chenodeoxycholic acid) helps prevent progression of the disease, but it cannot undo any damage already done. People may also be given statins because these medications lower lipid levels in the blood^[5].

Treatment of sitosterolemia consists of reducing the intake of foods that are rich in plant fats, such as vegetable oils, and taking cholestyramine resin. Doctors may also give the medication ezetimibe, which reduces the amount of cholesterol absorbed by the body^[5].

The goal of treatment is to manage lipid levels effectively and prevent complications. This may involve lifestyle changes, including dietary modifications, as well as medication to control cholesterol and triglyceride levels^[2].

Possible Complications

Many of these disorders can be very serious, or sometimes even fatal^[1]. When lipids are affected, they cause inter-related disorders like diabetes, cancer, infections, and inflammatory and neurodegenerative conditions^[2].

Abnormal levels of blood lipids cause fat deposits in artery walls, which initiates complications inside the blood vessels. The growing fatty buildup causes a variety of disorders related to blocked arteries, such as stroke or heart attack^[2].

People with Gaucher disease and carriers of the disease have an increased risk of developing Parkinson’s disease and related disorders^[4].