High blood cholesterol (hyperlipidemia)

What is it?

According to the NHLBI: cholesterol is “a waxy, fat-like substance your body needs for good health but in the right amounts”. There are two types of lipoproteins: LDL (“bad”), whose rise causes plaque to build up in the arteries, and HDL (“good”), which carries cholesterol and deposits to the liver to be removed. MedlinePlus adds a third type, VLDL, which carries more triglycerides than cholesterol and is also considered harmful because it contributes to plaque.

The CDC explains that blood cholesterol is a waxy substance made by the liver, and the body produces all it needs, while dietary cholesterol is found in animal products such as meat, poultry, fish, eggs and dairy. Triglycerides are blood fats used for energy; their rise together with low HDL or high LDL increases the risk of heart attack and stroke.

This page covers high cholesterol and blood lipids, and the NHS defines it as having too much of a fatty substance called cholesterol in the blood. This page does not cover detailed classifications of lipid disorder types.

Causes

According to the NHLBI, the most common cause is lifestyle habits: eating too much saturated fat raises LDL (advised not to exceed 10% of daily calories), physical inactivity, smoking (lowers HDL and raises LDL especially in women), stress (may raise hormones such as corticosteroids so cholesterol production increases), excessive alcohol (more than two drinks a day for men and one for women), and lack of sleep.

Genetics: “family members often have similar cholesterol levels”, and genetic mutations may cause familial hypercholesterolaemia, an inherited condition that raises cholesterol greatly because the body cannot remove LDL or process it in the liver (NHLBI, MedlinePlus).

Risk factors

Medical conditions that raise the risk according to the NHLBI: chronic kidney disease, diabetes, HIV/AIDS, hypothyroidism, lupus, obesity, polycystic ovary syndrome, and sleep apnoea. Medicines that may raise LDL or lower HDL: arrhythmia medicines, beta blockers, chemotherapy, diuretics, immunosuppressants, retinoids and steroids.

Age and sex: high cholesterol is most often diagnosed between ages 40 and 59, and women's risk rises after menopause (NHLBI). The NHS lists factors such as age over 50, male sex, South Asian or Sub-Saharan African descent, family history, a poor diet, inactivity, being overweight, smoking and alcohol. The CDC classes age, family history, type 2 diabetes and obesity among factors that cannot be controlled, and a diet rich in saturated and trans fats and physical inactivity among those that can be controlled.

Symptoms

“There are usually no signs or symptoms of high cholesterol” (MedlinePlus). The NHS and CDC stress that the only way to know is to have your cholesterol checked by the medical team.

How is it diagnosed?

According to the NHLBI, diagnosis relies on medical and family history, clinical examination and a blood test for cholesterol levels. The main tool is the lipid panel, which measures total cholesterol, LDL, HDL and triglycerides, and may include calculating non-HDL. The care provider may ask for fasting 8 to 12 hours before it.

The target for a healthy lipid profile according to the NHLBI: non-HDL below 130 mg/dL and HDL of at least 40 for men and 50 for women. The CDC states that total cholesterol above 200 mg/dL is considered high (for adults and children), and that optimal values are about 150 for total, about 100 for LDL and below 150 for triglycerides. These are general figures and the doctor interprets your result according to your overall risk.

Timing of testing according to the NHLBI: for children and adolescents it starts between 9 and 11 years and repeats every 5 years, and from age two if there is a family history. For adults 20 to 65 every 5 years for younger people, and every one to two years for men 45 to 65 and women 55 to 65; and after 65 yearly. An Lp(a) test is recommended when there is a family history of stroke or early heart disease or when the family history is unknown.

Treatment

The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.

Lifestyle according to the NHLBI: heart-healthy eating patterns such as TLC and DASH that reduce saturated fat and increase whole grains, vegetables, fruit and nuts and reduce salt; physical activity (consult the care provider before starting); losing 3 to 5% of body weight in people who are overweight helps lower LDL and raise HDL; managing stress; quitting smoking; sleeping 7 to 9 hours; and reducing alcohol.

Medicines (chosen with the doctor): statins are the best-known medicine for treating high cholesterol, reducing cholesterol production in the liver and lowering the risk of heart attack and stroke. Their possible effects include a raised risk of diabetes (especially in those at risk), raised liver enzymes on testing (and actual liver damage is “extremely rare”), and rare cases of muscle damage and cognitive problems. The NHLBI lists alternatives or additions to statins such as ezetimibe (blocks cholesterol absorption), bempedoic acid, lomitapide and mipomersen, bile acid sequestrants, and PCSK9 inhibitors, which are injections for high-risk cases or familial hypercholesterolaemia, often with a statin.

For people with familial hypercholesterolaemia, lipoprotein apheresis may also be used, with a filtering machine that removes LDL from the blood (MedlinePlus). The NHS notes that some people need a medicine alongside healthy eating and activity, and the source page did not list the medicine classes.

Do not change or stop a medicine without a doctor; the NHLBI stresses combining medicines with continued lifestyle changes and discussing the individual plan with the care provider.

Follow-up

When certain medicines are used (such as some medicines for familial hypercholesterolaemia) the care provider monitors liver enzymes regularly (NHLBI). This page does not cover detailed follow-up schedules.

Complications

According to the NHLBI and CDC: high LDL leads to plaque building up in the arteries, narrowing them and reducing blood flow, and a plaque may rupture and a clot form that partially or completely blocks the blood and oxygen reaching the heart, brain, kidneys, legs, arms or pelvis. The outcomes include angina, heart attack, heart disease and stroke, which the CDC describes as among the leading causes of death in the United States. MedlinePlus adds carotid artery disease and peripheral artery disease.

Prevention

According to the NHLBI risks are lowered by the same lifestyle: a heart-healthy diet with less saturated fat, regular physical activity, a suitable weight, quitting smoking, enough sleep, and less alcohol. The CDC states that evidence is strong that lower-cholesterol dietary patterns lower the risk of heart and vascular disease.

Living with it

Since there are no symptoms, follow-up relies on periodic testing and discussing the results and treatment plan with the care provider, and continuing a healthy lifestyle even when taking medicine (NHLBI, MedlinePlus). This page does not cover living with high cholesterol in detail.

Common questions