Often when cholesterol tests are performed laboratories will indicate, in addition to total, HDL, and LDL cholesterol readings, the ratio of total cholesterol to HDL cholesterol. Although nearly all experts now agree that it’s far more important to look at total cholesterol and LDL levels than at this ratio, there’s still so much talk of ratios that it’s helpful to understand what they mean. Also, if your total cholesterol is over 160 mg/dl, the ratio is a useful way to assess your risk for coronary heart disease.

The average American ratio of total to HDL cholesterol is about 5 to 1. For any given serum cholesterol, ratios below 5 are associated with a lower risk of coronary heart disease and ratios above 5 with an increased risk. But what if your total cholesterol level were 150 and your HDL cholesterol level only 25? This would give you a total-to-HDL ratio of 6, yet your risk of heart attack would be extremely low because your total cholesterol level and your LDL cholesterol level are so low.

On the other hand, though, if your total cholesterol were 300 mg/dl and your HDL were 75, your ratio would be 4 – and if you were to look only at the ratio, your risk of cardiovascular disease might appear to be lower. But in fact your risk of having a heart attack would be much higher than average – even though your HDL and the ratio looked okay – because your total cholesterol and LDL cholesterol are too high. Of course, if someone with the same 300 mg/dl total cholesterol had an HDL of 25 instead of 75, the risk of a heart attack would be much higher still. Once you realize that diet has more of an impact on LDL and total cholesterol than it does on HDL, you’ll realize that focusing on HDL and the ratio of total cholesterol to HDL cholesterol can be very misleading.

It’s important to understand, too, that whatever the ratio, it can give the wrong impression when HDL levels are low but total cholesterol and LDL are also low.

Keep in mind that a low-fat, low-cholesterol, high-fiber diet will maximally reduce your total cholesterol. Most of this reduction will be of the LDLs, but your HDLs may also drop. However, you shouldn’t be concerned over a drop in your “good” cholesterol level under these circumstances, because your ratio of total cholesterol to HDL will also tend to improve. A low HDL level only becomes more significant when your LDLs exceed 100 mg/dl, or when your ratio of total cholesterol to HDL is not improving. At that point you may want to consult your doctor, because you may still be at some risk for cardiovascular disease.

But rather than worry about a drop in HDL or an unfavorable ratio, it’s far better to focus instead on something you have more control over, such as lowering your total and your LDL levels – then you won’t have anything to worry about.

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