Dear Dr. Roach: Several years ago, I started going to a new doctor, who said the way to get the correct cholesterol number is to divide the HDL into the LDL, and if the answer is not 2.5 or lower, I have a problem and should be taking steps to lower it. My previous doctor stated you subtract the HDL from the LDL, and if it is below 100, it’s OK.

Which is correct? I am 68 years old now and in very good health. I was told by a another doctor I met that he’d never heard of the “2.5” solution.


Dear T.: There are four main cholesterol numbers acquired from a routine blood test: total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides. It’s hard to comprehend four numbers all at once, so you have mentioned two approaches to evaluate the cholesterol picture in a single number.

The first is the HDL:LDL ratio. Some authorities have described this number as the single best predictor of heart disease (from the standpoint of blood cholesterol levels). The higher the ratio, the higher the risk. A ratio of 2.5 is extremely good, with a very low risk of heart disease. A ratio of 3.5 or lower is generally considered desirable: At that level, the risk for heart disease is about half the average (the average ratio is 5). A ratio of 9.6 is associated with double the average risk.

The second is the non-HDL cholesterol, which is what you get when you subtract HDL from total cholesterol. This also has met with considerable acceptance, and a number below 100 is considered in the desirable range.

Personally, I think that since HDL cholesterol has independent predictive ability on the likelihood of coronary disease from LDL and total cholesterol, I use both absolute numbers. I think the ratio and non-HDL cholesterol are useful, but don’t tell the whole story.

Remember that cholesterol is only a part of the story for heart disease risk. Smoking and blood pressure are at least as important. Family history is too, and often is underappreciated. Diet, exercise and stress management are very important, and most of us physicians don’t pay enough attention to these.

Dear Dr. Roach: I am considering ankle replacement surgery. What is the success rate, and do you recommend it?


Dear S.F.: Rheumatoid arthritis is the indication for which ankle replacement surgery has been studied, and a 2004 study showed that with newer-type joints, about 90 percent were still successful after six years.

However, not a lot of these are done, so, as a general rule, I wouldn’t recommend it unless symptoms are pretty severe.

Email questions to ToYourGoodHealth@med.cornell.edu.

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