Cholesterol: which number on the report actually matters
Total cholesterol is the figure everyone quotes and the least useful one on the page. The two that predict most are usually read past.
A lipid profile has four or five lines on it. Patients are generally told one number, and it is usually the one that explains the least.
Reading the four lines
- LDL cholesterol — the particle that deposits in artery walls. The figure treatment is aimed at.
- HDL cholesterol — carries cholesterol away. Low is unfavourable; it falls with insulin resistance and inactivity.
- Triglycerides — circulating fat, strongly driven by refined carbohydrate, alcohol and insulin resistance. Responds fast to changes in diet.
- Total cholesterol — the sum of the parts, including the favourable ones. Least informative line on the page.
- Non-HDL cholesterol — total minus HDL. Captures all the particles that cause harm, and needs no fasting.
There is a fifth thing worth calculating, which no lab prints: the ratio of triglycerides to HDL. When triglycerides are high and HDL is low together, that combination is one of the plainest signals of insulin resistance available from a routine blood test — which places a cholesterol report squarely in a metabolic consultation rather than a cardiac one.
Why there are no symptoms to wait for
Raised LDL does nothing you can feel. It deposits silently over years, and the first symptom in a significant number of people is the event itself. This is the entire argument for testing before anything hurts, particularly where a parent or sibling had heart disease young.
What raises it, beyond food
- Insulin resistance and central weight — the commonest driver seen in the clinic
- An underactive thyroid, which raises LDL and is easily tested and easily missed
- Kidney disease, and some medicines including steroids
- Familial hypercholesterolaemia — inherited, often with a strong family history of early heart attacks, and not a diet problem
- Trans fats and hydrogenated banaspati, which lower HDL while raising LDL
What a consultation about lipids covers
The full profile rather than the total, blood pressure, waist, HbA1c and fasting glucose, thyroid function, kidney and liver function, the family history asked for by name and age, and every medicine and supplement you take. Lipids are not read in isolation here, because they do not occur in isolation.
If a statin or other lipid-lowering medicine has been prescribed, it is not stopped here and not substituted. Chest pain, pain spreading to the arm or jaw, breathlessness or sweating is an emergency — go to a hospital, not to a clinic appointment.
Questions people ask
- My total cholesterol is normal. Am I safe?
- Not necessarily. Total cholesterol adds together the LDL that drives arterial disease and the HDL that does not, so a low HDL and a high LDL can produce a reassuring total. Ask for the LDL figure, the triglycerides, the HDL, and the non-HDL cholesterol, which is simply total minus HDL and is a better single predictor than total.
- Why do South Asians develop heart disease earlier?
- Risk in South Asian populations tends to appear at younger ages and at lower body weights than in European populations, with a pattern of higher triglycerides, lower HDL and more central fat for the same body mass index. It means that a result called borderline on a general chart may deserve attention sooner here, and that screening by age alone misses people.
- Can diet alone bring cholesterol down?
- Diet and activity move triglycerides substantially and LDL more modestly. How much is possible depends on why the figure is raised: a familial pattern, where the body handles LDL abnormally from birth, does not respond to diet the way a diet-driven pattern does, and that distinction needs to be made rather than assumed.