Written by Dimitrios Vrachatis, Specialist Cardiologist, PhD, National and Kapodistrian University of Athens.
What is dyslipidaemia?
Dyslipidaemia is an abnormal level of cholesterol or other lipids in the blood.
Cholesterol is an unsaturated sterol in the lipid family. It is a basic component of cell membranes and essential for normal body function.
Why is high cholesterol harmful?
Different forms of dyslipidaemia contribute to atherosclerotic plaque in arterial walls, narrowing or blocking the lumen. This can affect any artery, but is particularly important in the coronary arteries supplying the heart and the arteries supplying the brain, such as the carotids.
Over time, high cholesterol can lead to coronary disease and myocardial infarction, carotid disease and stroke, or peripheral arterial disease and intermittent claudication, pain when walking.
What causes it?
The main cause is genetic predisposition or heredity. Other causes include:
- Diabetes
- Hypothyroidism
- Nephrotic syndrome
- Excessive alcohol
- Obesity
- Cushing’s syndrome
- A sedentary lifestyle
What are lipoproteins?
Lipoproteins transport lipids for energy production, storage, steroid hormone production and bile acid production. They contain:
- Esterified and non-esterified cholesterol, produced in the liver, brain and intestine
- Triglycerides (TG)
- Phospholipids
- Apolipoproteins
What types of lipoprotein are there?
Blood contains:
- Chylomicrons and very-low-density lipoprotein (VLDL)
- Low-density lipoprotein (LDL), known as “bad” cholesterol
- Intermediate-density lipoprotein (IDL)
- Lipoprotein(a), Lp(a)
- High-density lipoprotein (HDL), known as “good” cholesterol
What does LDL do?
LDL mainly carries cholesterol to tissues, which is why it is often called “bad” cholesterol.
What does HDL do?
HDL removes cholesterol from tissues, which is why it is often called “good” cholesterol.
What does VLDL do?
VLDL transports triglycerides (TG).
What is lipoprotein(a), or Lp(a)?
Lp(a) resembles LDL but has a different apolipoprotein. It is associated with vascular disease, including coronary disease and peripheral arterial disease, and aortic stenosis. Interventions targeting its levels have not shown reversal of cardiovascular risk.
Levels are genetically determined and remain stable throughout life. Levels above 50 mg/dL are considered associated with increased risk.
Does high cholesterol cause symptoms?
No. Abnormal circulating lipid levels are silent but increase cardiovascular risk. Symptoms may arise from the diseases they indirectly cause.
Possible physical signs include:
- Xanthelasmata: yellowish areas around the eyelids
- Xanthomas: yellowish deposits around tendons
- Corneal arcus: a white or grey ring around the edge of the eye’s coloured area
How is high cholesterol lowered?
Treatment includes:
- Immediate and permanent smoking cessation
- Physical activity
- Improved diet
- Medication
What is the treatment target?
LDL reduction is the main treatment target.
Both the threshold for treatment and the target depend on the estimated ten-year risk of adverse cardiovascular events. The cardiologist calculates and regularly reassesses this risk.
The cited European Society of Cardiology guidelines (2019) give the following LDL targets:
- Low risk: below 116 mg/dL
- Moderate risk: below 100 mg/dL
- High risk: below 70 mg/dL
- Very high risk: below 55 mg/dL
How do I know whether my cholesterol is high?
A blood test provides the answer. However, normal values are not the same for everyone: they depend on individual cardiovascular risk. Consult your cardiologist. Laboratory reference ranges may be outdated, and even current ranges require a detailed history to determine your risk category.
Which medicines are used?
Treatment generally uses statins, alone or with ezetimibe, an inhibitor of cholesterol absorption.
Beyond lipid lowering, statins have additional anti-inflammatory and antioxidant effects, known as pleiotropic effects.
For very high-risk patients who do not reach the target with a statin and ezetimibe, injectable monoclonal antibodies, PCSK9 inhibitors, may be used.
What changes during pregnancy?
During pregnancy, the only medicines permitted are bile acid sequestrants because they are not absorbed into the systemic circulation.