Total cholesterol
Also known as: cholesterol, serum cholesterol, TC
The sum of all the cholesterol carried in blood by lipoproteins: LDL, HDL and the remainder. One line of a lipid profile, useful mainly as the starting point for the ratios and the non-HDL value that guide cardiovascular risk assessment.
- Also known as
- cholesterol, serum cholesterol, TC
- Units
- mmol/L (UK) or mg/dL (US); 1 mmol/L ≈ 38.7 mg/dL
- Measured by
- Lipid profile, Thyroid function tests
What it is and what it does
Cholesterol is a waxy molecule every cell needs for its membranes and for making steroid hormones, bile acids and vitamin D. It does not dissolve in water, so it travels in blood packaged with proteins as lipoproteins. The total is dominated by LDL cholesterol, the fraction deposited in artery walls, and HDL cholesterol, the fraction being carried back to the liver. A high total is therefore not always harmful (a large HDL share is protective) and a normal total can hide a poor pattern, which is why risk calculators use the ratio of total to HDL and guidelines increasingly track non-HDL cholesterol instead.
Why it may be higher
- Diet high in saturated fat, excess weight, inactivity
- Familial hypercholesterolaemia and other inherited lipid disorders
- Hypothyroidism, kidney disease with heavy proteinuria, cholestatic liver disease
- Pregnancy; some medicines (corticosteroids, some antiretrovirals, isotretinoin)
Why it may be lower
- Hyperthyroidism, malnutrition, malabsorption
- Severe acute illness, cancer, advanced liver disease
- Lipid-lowering treatment
A high or low value can be associated with several different situations. The result is interpreted with other results, symptoms, history and clinical findings.
What can affect the result
- Acute illness, surgery and heart attack lower cholesterol for several weeks
- Weight change, alcohol and pregnancy
- Fasting is no longer required for most purposes but changes triglycerides more than cholesterol
Medicines that can change it
Each medicine page lists its effect on this marker under "Effects on tests and results", with the source.