CHAPTER FIVE-THE FRIEDEWALD EQUATION-AN EXTREME DEMONSTRATION IN PHYSICIAN IGNORANCE
There is a show out now called, 'Are You Smarter Than A 5th Grader?'
For most docs when it comes to understanding math, I mean really basic math, the overwhelming answer will be no. Let's face it, when most people hear the word math, they cringe, their bellies tighten up and some of us may even vomit. But I am not talking about calculus or even algebra. What I am referring to here is simple addition, subtraction and division. You do not even need to multiply (thank goodness).
Let me explain what this equation is and why it is important you understand it.
So what exactly is this Friedewald Equation anyway? In the US when you go to the lab to have your lipid profile checked there are only three things measured. These are the Total Cholesterol, the HDL and the triglycerides. These three values are then used to calculate the LDL. It is important to realize that the LDL is not measured directly from the blood. This has profound implications when one is trying to interpret the lipid profile.
The equation states that the LDL is equal to the Total Cholesterol minus the HDL and subtracted from this is the triglycerides divided by 5 (see below).
LDL (calculated) = Total Cholesterol - HDL - TG/5
So when you give your blood the numbers of the total cholesterol, the HDL and TGs are placed into the equation and voila, out comes your LDL. Now look very carefully at how simple this equation is. It is simple, is it not? What do you notice? There is a lot of subtraction going on and one fraction. This fraction is important because as you divide the same number into a lower number what do you think happens? For instance, divide one hundred by five. You get twenty of course. Now divide fifty, a lower number, by five. Now we get ten. So dividing a lower number by the same number results in a LOWER number.
It is quite simple.
This lower number is particularly important because it is being subtracted from another part of the equation. So what happens if you subtract a lower number from something? Unless you are dealing with negative integers you will get a HIGHER number. As an example, subtract five from ten. The result is five. Now subtract two, a lower number from ten and eight is the result. Eight is higher than five. Still not so tricky.
Now let us digress a little and talk about what the total cholesterol really means. We have not done this yet and it really is quite simple. The total cholesterol is just that, the total cholesterol. We arrive at the total cholesterol by adding together the HDL, LDL (remember the LDL is calculated here, not measured) and the VLDL (for some reason the IDL does not even get honorable mention). So the equation looks like this:
Total Cholesterol = HDL + LDL + VLDL; where VLDL = TG/5
Now, what do you think happens to the total cholesterol if you increase, say, the LDL? That is correct, the total goes up. What about if the VLDL increases? Uh huh, the total goes up. Wait a minute. What if the HDL goes up? Bingo, so too will the total cholesterol.
As a very, very important side note, this is why when one begins to lower their carbs and to eat more fat and cholesterol the total cholesterol may increase. So it is very important NOT to panic. A very common scenario is the following; a patient figures out that the correct way to eat is to eat less carbs and to eat more fat, protein, and cholesterol. They go for their lab work and their doc notices that while the HDL went up dramatically the total cholesterol went up too. Then the patient is admonished against what they did. They are told those diets are bad for you. Then they are told to start a low fat, low cholesterol diet and guess what; when they check their numbers out in a few months they are so bad they wind up on cholesterol lowering medications.
This is an absolute tragedy. The physician who advises their patient to abandon a low carb, more fat, more cholesterol, more protein diet because the total cholesterol went up, but so, too, did the HDL, is demonstrating extreme ignorance of what total cholesterol is all about. This should never happen, but yet it happens every day. Every single day in almost all physician’s offices all over the world. But wait, it gets even worse.
Remember I said it is important to know that LDL is calculated, not measured. The reason this is important is because when the HDL goes up the total cholesterol may go up. And when the TGs go down you wind up subtracting a smaller number from the rest of the equation. Well, look at the equation. What will happen to your total cholesterol when you raise your HDL? That is correct, it will go up. Again, look at the equation. What do you think you will get when you subtract a higher HDL from a higher total cholesterol? And remember, the total cholesterol is higher because the HDL is higher. Let us do some math together to figure it out.
Subtract thirty-five, a common HDL to see, from a total cholesterol of two hundred thirty. You get one hundred ninety five. Now subtract fifty, a pretty common rise to see when you are eating the correct way, from a total cholesterol of two hundred sixty five. We now get two hundred fifteen. Do some more to prove it to yourself. The point, to say it again, is that when we subtract a higher number from a higher number we wind up with a higher number. Now when we subtract a smaller number from this higher number the result will be a higher number. The smaller number we are subtracting results from the TGs being lower when we lower our carb intake and eat more fat and cholesterol. And from the above discussion we have seen that when we divide a lower number by the same number the result is a lower number. It is this lower number we are subtracting form the higher number we arrived at above.
So the end result to the calculated LDL value when your total cholesterol and HDL go up and your triglycerides go lower, IS THAT THE LDL GOES HIGHER BECAUSE OF THE WAY IT IS CALCULATED! We want the HDL to go higher. We want the fats in your blood to be lower. When this happens it will oftentimes raise the LDL. No, it does not happen in everyone, but it happens in just about everyone and it is solely due to the way the LDL is calculated.
Now guess what happens when you walk into your doc's office after spending three months eating the way you should. Your HDL will be higher, which is great, but this may make the total cholesterol increase. Your triglycerides will be lower, which is awesome because that is what you want. But your LDL will be higher. Again, based on the formula the lab uses to calculate the LDL, the LDL will be higher when your HDL is higher and your TGs are lower.
When your doctor reads your lab report do you really think that she or he is going to say, "Wow, great, everything's fantastic!" Not a chance. All your doc sees is an elevated total cholesterol and an elevated LDL. They panic, your doctor that is, and immediately want to place you on cholesterol lowering meds. But wait a minute; if they are so interested in lowering the calculated LDL we can do this by raising your TGs or lowering your HDL: exactly what we do not want to do.
Just to bring everyone up to date. I think the latest guidelines say to keep the LDL below seventy if you have risk factors for heart disease. I have difficulty with this concept because we are using the calculated LDL and we are not measuring it directly. Sure, the cholesterol lowering meds work, but all too often I see well trained cardiologists freaking out because they cannot get the calculated LDL below seventy, or even one-hundred for that matter. And they will just keep pushing the dose higher and higher and higher. If they just stopped and thought the process through they would realize that in the vast majority of people this approach will not work.
Why?
Because their patient’s TGs may be low and their HDLs may be where they should be, so based on the calculation, the LDL will never get below 70.
But one cannot really harp on these docs for what they are doing. They are simply doing what they were trained to do. They apply the guidelines, do not think for themselves and they push the accepted medications for the treatment of cholesterol. But this would still be defined as ignorance, would it not? And whom do we blame for the millions of people who die each year because of this?
The lipid profile numbers that we should be paying attention to are the HDL and TGs only. What I like to use is the TG to HDL ratio. Keep this ration at or under two and you are sitting pretty. If it rises above two, be careful, because now not only are you looking at an increased risk of heart disease, but also diabetes and cancer. Two other diseases we will be discussing shortly.
Now on to chapter six.
Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened
-Winston Churchill
Comments, anyone :-)
Dr. James E. Carlson B.S.,D.O.,M.B.A.,J.D.
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