LDL cholesterol test explained

Cholesterol travels through the blood in lipoproteins. Low-density lipoproteins (LDL) carry cholesterol from the liver to the tissues; when there is too much of it, cholesterol builds up in artery walls and forms plaques — this is atherosclerosis, the main cause of heart attack and stroke. That is why LDL is the most important lipid-panel marker when assessing and lowering heart risk. Unlike total cholesterol, LDL has no single "normal" value that applies to everyone: guidelines set a target value according to risk — for a healthy person with no additional risk factors the target is less strict, while for someone who has had a heart attack or who has diabetes it is considerably lower; the specific target is set by a doctor. LDL rises because of a diet high in saturated fat, excess weight, heredity (familial hypercholesterolaemia — an inherited disorder in which LDL is markedly raised from a young age), an underactive thyroid, and certain medicines. Most often LDL is calculated from total cholesterol, HDL and triglycerides, and less often measured directly.

• As part of a lipid panel — as a preventive assessment of cardiovascular risk
• When risk factors are present: raised blood pressure, diabetes, smoking, excess weight, heart disease in the family
• When familial hypercholesterolaemia is suspected — very high cholesterol in a young person, or early heart disease in relatives
• To monitor the effect of lifestyle changes or treatment — whether the target value is being reached

LDL cholesterol 2.6–3 mmol/l: slightly above the MedlinePlus desirable value (2.6 mmol/l). For a healthy person with no risk factors this is often acceptable; with diabetes or heart disease the target is lower — the doctor decides.

LDL cholesterol 3–4 mmol/l: raised. This is usually a reason to assess overall heart risk (blood pressure, smoking, diabetes, age) and to discuss lifestyle changes with a doctor.

LDL cholesterol 4–5 mmol/l: clearly raised. The doctor assesses overall risk and, if other factors are present, often considers more active lowering.

LDL cholesterol above 5 mmol/l: very high. A value like this, especially in a young person or when there is early heart disease in the family, leads a doctor to suspect inherited familial hypercholesterolaemia and to test family members.

A raised LDL cholesterol is most often linked to a diet high in saturated fat, excess weight, low physical activity, heredity and certain conditions — an underactive thyroid, kidney and liver disease, diabetes. It causes no symptoms; what it means depends on overall heart risk, which a doctor assesses before setting a personal target.

• A diet high in saturated fat
• Excess weight and low physical activity
• Heredity — familial hypercholesterolaemia
• Reduced thyroid function
• Kidney and liver disease, diabetes
• Certain medicines
• Smoking — it worsens the lipid profile

What to discuss with a doctor:

• Overall cardiovascular risk — your LDL target depends on it
• The full lipid panel: HDL, triglycerides, non-HDL; sometimes apolipoprotein B and lipoprotein (a)
• TSH — an underactive thyroid raises LDL
• Family history — early heart disease or very high cholesterol in relatives
• When to repeat the test after lifestyle changes

A low LDL cholesterol is usually favourable for the heart. A very low value sometimes accompanies an overactive thyroid, liver disease, chronic illness or inadequate nutrition, and the most common reason of all is cholesterol-lowering treatment.

• Cholesterol-lowering treatment
• Increased thyroid function
• Liver disease
• Chronic illness, inflammation, inadequate nutrition

What to discuss with a doctor: whether there are other signs, such as weight loss or tiredness; and thyroid and liver markers, if the value is unexpectedly low without treatment.

At the Medicina practica laboratory in Lithuania, an LDL cholesterol test costs from €7 and a full lipid panel from €20 (September 2026 pricing). Under the cardiovascular disease prevention programme, a family doctor orders the lipid panel free of charge.