Cholesterol ratio: Is it important?

Calculating your cholesterol ratio can provide useful information about your heart disease risk, but it isn't useful for deciding what treatment you should have to reduce your heart disease risk. Your total cholesterol and low-density lipoprotein (LDL, or "bad") cholesterol levels are more useful in guiding treatment decisions than is your cholesterol ratio.

You can calculate your cholesterol ratio by dividing your high-density lipoprotein (HDL, or "good") cholesterol into your total cholesterol. For example, if your total cholesterol is 200 milligrams per deciliter (mg/dL) (5.2 millimoles per liter, or mmol/L) and your HDL cholesterol is 50 mg/dL (1.3 mmol/L), your cholesterol ratio is 4-to-1. The goal is to keep your cholesterol ratio 4-to-1 or lower. A higher ratio indicates a higher risk of heart disease; a lower ratio indicates a lower risk.

For treatment purposes, it's more important to know absolute numbers for all your cholesterol levels — including HDL, LDL and total cholesterol — than to know ratios. This is because HDL cholesterol and LDL cholesterol both affect your heart disease risk, and treatment may be directed at improving both. For example, if you have LDL cholesterol of 100 mg/dL (2.6 mmol/L) or above, the main goal of treatment is to lower your LDL cholesterol.