Heart and vessels
LDL-cholesterol
The 'bad' cholesterol that is deposited in the blood vessel wall; the most important cholesterol value for risk estimation and treatment.
Everything about this testWhat it measures
LDL (low-density lipoprotein) is the transport particle that carries cholesterol from the liver to the tissues. Too many LDL particles penetrate the blood vessel wall and build up there into hardening of the arteries (atherosclerosis). The higher the LDL and the longer it is raised, the greater the chance of a heart attack or stroke; lowering LDL demonstrably lowers that risk. Most laboratories calculate LDL from total cholesterol, HDL and triglycerides (Friedewald formula); with high triglycerides it is measured directly.
- Increased risk of cardiovascular disease due to hardening of the arteries
- Familial hypercholesterolemia (inherited high cholesterol): the GP considers this with an LDL above 5 mmol/l
- Effect of cholesterol-lowering treatment (target value depends on the risk)
High
A raised LDL cholesterol causes no symptoms, but over time increases the chance of hardening of the arteries, a heart attack and a stroke. How much this counts depends on the level, the duration and the other risk factors; the Dutch GP guideline (NHG) links treatment to the total risk. With a low or moderately increased risk there is no target value and cholesterol-lowering medicines are usually not needed; with a high risk the target value is below 2.6 mmol/l and after a cardiovascular disease below 1.8 mmol/l. With an LDL above 5 mmol/l, especially with cardiovascular disease at a young age in the family, there may be inherited high cholesterol. Other causes of a high value: an underactive thyroid, kidney disease with protein loss, liver disease with bile congestion, pregnancy, anorexia and some medicines.
Low
A low LDL is usually favorable: it is due to genetic makeup, a healthy lifestyle or cholesterol-lowering medicines, and according to the guideline a very low LDL due to medicines is considered safe. An unexplained low or falling LDL may go with an overactive thyroid, malnutrition, severe liver disease, a chronic inflammation or an acute illness; an inherited disorder of fat metabolism is rare. A low LDL itself causes no symptoms.
If your result is abnormal
With a raised LDL, the GP estimates the ten-year risk with SCORE2 and discusses lifestyle; with a high risk or an LDL above 5 mmol/l, a repeat measurement usually follows, along with additional tests (thyroid, kidney function, glucose) and, if needed, a statin or referral for DNA testing for inherited high cholesterol.
Reliability
LDL is a risk marker and the most important value for guiding treatment, but not a diagnosis on its own. According to the Dutch GP guideline (NHG) on cardiovascular risk management, the GP assesses LDL within the SCORE2 risk estimate, which takes into account age, sex, smoking, blood pressure and non-HDL cholesterol; which value is 'too high' depends on that risk. According to the guideline, fasting is not needed. Because LDL is usually calculated, the result is unreliable with high triglycerides (above about 4.5 mmol/l); the laboratory then measures LDL directly or the GP uses non-HDL.
Limitations
- Calculated LDL (Friedewald) is unreliable with high triglycerides, for example after a fatty meal or alcohol; non-HDL cholesterol or directly measured LDL is then the better measure.
- During and for a few weeks after an acute illness, surgery or heart attack, LDL is temporarily lowered.
- Pregnancy, an underactive thyroid, kidney disease, bile congestion and medicines such as corticosteroids and water pills raise the value; statins and other cholesterol-lowering drugs lower it.
- The value fluctuates from day to day; with a borderline value, a second measurement is needed before treatment is started.
How common is this
In 2024, over 1.6 million people in the Netherlands were known to their GP with a disorder of fat metabolism, including high cholesterol; that is about 9 in 100 inhabitants, most often between the ages of 55 and 70. Inherited high cholesterol runs in families: children, brothers and sisters of someone with the gene defect each have a 1 in 2 chance of having it too.
Who is this useful for
Useful for a cardiovascular risk estimate (the SCORE2 table applies from age 40, earlier with risk factors), with cardiovascular disease or strongly raised cholesterol in the family, with diabetes, high blood pressure, kidney damage or smoking, and for monitoring cholesterol-lowering medicines. In young, healthy adults without risk factors, a one-time measurement can rule out inherited high cholesterol; repeat measurement is then not needed.
Downsides and risks
- In people with a low risk, a slightly raised LDL is sometimes wrongly seen as a reason for medicines; the guideline links treatment to the total risk, not to the single value.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results