Dyslipidemia

Dyslipidemia, dyslipidaemia, or hyperlipidemia is the alteration in the concentration of lipids and lipoproteins in the blood.

The body's two main lipids, or fats, are cholesterol and triglycerides. Cholesterol is a waxy substance found in cell membranes and bile that participates in the absorption of fats and fat-soluble vitamins, as well as in the synthesis of vitamin D and certain hormones, such as estrogens, testosterone, and cortisol. Cholesterol is produced by the body, but it is also obtained from food. Triglycerides are formed in the intestine and liver from fatty acids produced by the body or obtained from food. They are stored in adipose cells, and their function is to be broken down to provide the energy required for the body's various metabolic processes.

Lipoproteins, in turn, are the proteins responsible for transporting fats through the bloodstream. They may be low-density lipoproteins (LDL), which carry so-called "bad cholesterol" to the body's tissues, or high-density lipoproteins (HDL), which transport so-called "good cholesterol" from tissues to the liver for elimination in the form of bile.

Depending on the altered values, there are several types of dyslipidemia:

• Isolated hypercholesterolemia: increased levels of low-density lipoproteins or LDL. A healthy level is below 100 mg/dL.
• Isolated hypertriglyceridemia: increased triglyceride levels. A healthy concentration is below 150 mg/dL.
• Mixed or combined hyperlipidemia: elevation of both of the above values.
• Reduced high-density lipoproteins or HDL: the optimal level should be equal to or greater than 60 mg/dL.

According to their origin, they are classified into two groups:

• Primary dyslipidemia: of genetic origin and not associated with any other disease.
• Secondary dyslipidemia: linked to one or more underlying diseases. It is the most common form.

Symptoms

Dyslipidemia usually does not cause visible symptoms until complications arising from elevated lipid levels develop. However, in some cases, primary dyslipidemias with particularly high levels may manifest as follows:

• Eruptive xanthomas: skin and tendon nodules formed by fat deposits.
• Corneal arcus: lipid deposits in the cornea appearing as opaque white or gray rings.
• Xanthelasma: small deposits of accumulated fat located beneath the skin of the upper and lower eyelids, generally near the lacrimal area.

Causes

The main causes of secondary dyslipidemia are the following:

• Unhealthy lifestyle habits: excessive consumption of foods rich in saturated fats, trans fats, and cholesterol, together with a lack of physical exercise. Alcohol and tobacco consumption also contribute to altered lipid levels.
• Certain diseases, such as diabetes, primary biliary cirrhosis, chronic kidney disease, nephrotic syndrome, or hypothyroidism.
• Certain medications, such as corticosteroids, retinoids, diuretics, beta-blockers, cyclosporine, antiretroviral drugs, or oral estrogens.

Primary dyslipidemia, in turn, is caused by a series of genetic mutations that alter lipid production and elimination processes, leading to one of the following situations:

• Overproduction or defective clearance of triglycerides and/or LDL lipoproteins.
• Insufficient production or excessive clearance of HDL lipoproteins.

Risk factors

The likelihood of developing dyslipidemia increases in the following circumstances:

• Family history.
• Regular consumption of foods rich in fats and cholesterol.
• Sedentary lifestyle.
• Obesity.
• Excessive alcohol consumption.
• Smoking.
• Presence of diseases or use of medications that alter blood lipid levels.
• Age: LDL lipoprotein concentration increases slightly with age, particularly in men and postmenopausal women.

Complications

Dyslipidemia is a major cardiovascular risk factor and may have serious consequences for the body. Excess cholesterol tends to accumulate in arterial walls, forming plaques that narrow the arteries until they become obstructed, reducing or blocking blood flow. This disorder, known as atherosclerosis, can affect any artery in the body and may be life-threatening. If the arteries supplying the heart become blocked (coronary artery disease), blood flow to the myocardium may be interrupted, resulting in a myocardial infarction. Likewise, blockage of cerebral arteries may lead to a stroke. When other arteries of the body are affected (peripheral arterial disease), severe pain, cramping, numbness, and weakness in the limbs may occur. In some cases, this condition can progress to gangrene, which may even require amputation of the affected limb.

Elevated triglyceride levels may cause enlargement of the liver or spleen, manifested by shortness of breath, confusion, and tingling or burning sensations in the hands and feet. Furthermore, hypertriglyceridemia increases the risk of developing pancreatitis, an inflammation of the pancreas that can be fatal.

Prevention

Preventing dyslipidemia involves maintaining a healthy lifestyle:

• Reduce the consumption of fats, sugars, and alcohol.
• Avoid tobacco use.
• Moderate calorie intake.
• Increase the consumption of fruits, vegetables, legumes, whole grains, and raw nuts.
• Promote the consumption of omega-3-rich foods, such as flax and chia seeds, oily fish, olive oil, seafood, avocado, and leafy green vegetables.
• Engage in regular physical exercise.
• Maintain a healthy weight.

Which specialist treats dyslipidemia?

Dyslipidemia is assessed and treated by specialists in Internal medicine and Endocrinology and Nutrition.