High cholesterol: what it means, when to worry and what to ask for

You had a blood test, cholesterol came out flagged in red, and the first thing you did was search for high cholesterol symptoms. The short answer is uncomfortable: there are none. High cholesterol does not hurt, does not make you dizzy, does not tire you.^[5] That is what makes it easy to ignore and, at the same time, what makes a single number on a sheet of paper so worrying. This text explains what the lipid profile measures, which thresholds guidelines use, why an isolated result says little, and what to bring to the appointment so that it is useful.

Before going on, a distinction. High cholesterol in itself is not an emergency. What is, with or without high cholesterol, is chest pain or pressure, sudden shortness of breath, weakness or numbness on one side of the body or trouble speaking. If you have any of that now, close this page and seek medical care.

High cholesterol cannot be felt

There are no signs or symptoms of having high cholesterol; the only way to know is to measure it in the blood.^[5] That is why the search for “symptoms” points in the wrong direction: the person with the highest cholesterol in the building may feel perfectly fine. What high cholesterol does is silent and slow: over years it builds up in artery walls and raises the risk of heart disease and stroke.^[4]

What the lipid profile measures

When the lab reports “cholesterol”, it actually reports several numbers, and each one tells a different part of the story. Reading them together is what separates a useful result from a scare.

Total cholesterol

It is the sum of all the cholesterol travelling in the blood. It serves as a first look, but on its own it misleads: two people with the same total can have very different profiles depending on how it is split among the fractions below.

LDL, the one that builds up

LDL is known as the “bad” cholesterol. It is the fraction that, in excess, is deposited in the arteries, and it is the number on which almost all guideline decisions are based.^[4]

HDL, the one that collects

HDL is known as the “good” one because it carries cholesterol back to the liver. An HDL below 40 mg/dL in men or 50 mg/dL in women is considered low, and 60 or more is considered favourable.^[4] One nuance: an extremely high HDL, above about 90 mg/dL, can no longer be used as a sign of protection.^[2]

Triglycerides

They are another blood fat, very sensitive to what you ate and drank in the previous days and to glucose. European guidelines set no target, but consider that below 150 mg/dL the risk is lower, and that higher values call for looking for other risk factors.^[2] It is the fraction that changes most with fasting, which is why the Mexican standard asks for 9 to 12 hours without food to measure them.^[1]

Non-HDL cholesterol

It is a simple subtraction: total cholesterol minus HDL.^[2] It groups all the cholesterol that can build up, not just LDL, and has a practical advantage: it can be calculated without fasting.^[1] If your report does not include it, you can do the subtraction yourself.

The thresholds guidelines use

Cut-off numbers vary a little by guideline and, above all, by each person’s risk. The Mexican standard for dyslipidaemias defines a profile “under control” and the values that raise suspicion of a problem like this:^[1]

US references are similar: total below 200, LDL below 100, non-HDL below 130.^[4] European guidelines go further and adjust the LDL goal to each person’s risk: below 116 mg/dL for low risk, below 100 for moderate, below 70 for high and below 55 for very high.^[2] Notice what this means: there is no single “normal” LDL number. That is why the lab range is not your personal norm, as we explain in this other text.

One result is a snapshot: context and trend

Guidelines do not decide on cholesterol alone. The US guideline estimates 10-year risk in adults aged 40 to 75 by combining cholesterol with age, sex, blood pressure, smoking and diabetes, and adds “risk-enhancing factors”, among them having a first-degree relative with premature cardiovascular disease: a man before age 55 or a woman before 65.^[3] That is why an LDL of 140 in someone who smokes and has high blood pressure is not the same LDL of 140 in someone who does not.

The second ingredient is time. Cholesterol varies from one sample to the next for biological and laboratory reasons; the British guideline on familial hypercholesterolaemia expressly asks for two LDL measurements before drawing conclusions.^[6] And the Mexican standard sets the pace: with no risk factors and values within limits, repeat every five years; with risk factors or family history, every one or two years.^[1] If you do not yet know how to read a report without getting scared, this guide comes first.

What raises cholesterol temporarily

Before concluding that “you have high cholesterol”, it is worth checking whether the result was taken at a bad moment. Several situations alter lipids without meaning a permanent problem:

• Incomplete fasting. Total, HDL and non-HDL can be measured without fasting, but triglycerides and calculated LDL need 9 to 12 hours without food.^[1] A breakfast before the draw changes the result.
• Recent illness, surgery, pregnancy or weight loss. The Mexican standard states that it is not useful to measure lipids during pregnancy or in the six weeks after an acute illness, surgery or weight loss: the value at that moment does not represent your baseline.^[1]
• Untreated hypothyroidism. A slow thyroid raises cholesterol and triglycerides, and they improve when it is treated; the Endocrine Society recommends ruling out hypothyroidism before treating cholesterol with medicines.^[8]
• Medicines. Some drugs for other conditions raise LDL, among them certain beta-blockers, antiarrhythmics and steroids.^[9] Write down what you take.
• Other conditions. Diabetes, chronic kidney disease and obesity also raise the risk of high cholesterol.^[9]

And one factor that is not temporary but is modifiable: smoking lowers HDL, particularly in women, and raises LDL.^[9]

When to think about an inherited form

Most high cholesterol is explained by age, diet, weight and diffuse genetics. But there is an inherited form, familial hypercholesterolaemia, in which LDL is very high from birth, and spotting it changes the conversation. Guidelines agree on the clues:

• An LDL of 190 mg/dL or more. The US guideline calls it severe hypercholesterolaemia, treats it as a separate group with high lifetime risk and does not require calculating 10-year risk to decide.^[3]
• A total cholesterol above 7.5 mmol/L (about 290 mg/dL), or a personal or family history of coronary heart disease before age 60, are the two reasons the British guideline asks to suspect it.^[6]
• Premature heart attack in the family: before age 55 in men or 60 in first-degree female relatives, or early sudden cardiac death.^[7]
• Tendon xanthomas: fatty lumps in the tendons, often the Achilles; or a whitish arc in the cornea before age 45.^[7]

Two honest clarifications. First: before talking about an inherited form, secondary causes must be excluded, with thyroid, kidney, liver and glucose checked.^[7] Second: none of these clues is a diagnosis; they are the reason to ask for an appointment soon instead of waiting for the next check-up.

Warning signs: when you do not log, you consult

Two different lists. The first has nothing to do with the cholesterol on the sheet: these are emergencies in anyone.

• Pain, pressure or burning in the chest, especially if it spreads to the arm, jaw or back, or comes with cold sweat and nausea.
• Sudden shortness of breath without an effort that explains it.
• Weakness, numbness or drooping on one side of the face or body, trouble speaking or understanding, sudden loss of vision.
• Fainting or intense palpitations with dizziness.

The second list is not about emergencies, but about “do not wait until next year”: ask for an appointment in the coming weeks if you have an LDL of 190 mg/dL or more,^[3] a first-degree relative with a heart attack before age 55 (man) or 60 (woman),^[7] or lumps in the tendons.^[7]

What to bring to the appointment

A cholesterol appointment is usually short and decided in the first minutes. What you bring in your hand defines how good that decision is.

1. All your lipid profiles, with dates, not just the latest. The trend is the data.
2. The conditions of the draw: hours of fasting, whether you were ill, pregnant or on a diet, which medicines you were taking.
3. Home blood pressure: seven days in a row, morning and evening, two readings per session.
4. Fasting glucose or HbA1c if you have them, and your current weight and waist.
5. If you smoke, how much.
6. Family tree: who had a heart attack or stroke, at what age, who has high cholesterol or takes medicine for it.
7. TSH if it was ever measured, and any thyroid, kidney or liver diagnosis.

With that folder, your doctor can calculate your risk, decide whether to repeat the profile, rule out a secondary cause and, only then, talk about what to do.