Chapter 5 – The Friedewald Equation – An Extreme Demonstration of Physician Ignorance
There’s a show now called Are You Smarter Than A Fifth Grader? For most papers, 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 wince, their stomachs tighten, and some of us may even throw up. But I’m not talking about calculus or even algebra. What I am referring to here is simple addition, subtraction and division. You don’t even need to multiply (thank God). Let me explain what this equation is and why it is important for you to understand it.
So what exactly is this Friedewald equation anyway? In the US, when you go to the lab to check your lipid profile, only three things are measured. These are Total Cholesterol, HDL and triglycerides. These three values are then used to calculate the LDL. It is important to realize that LDL is not measured directly from the blood. This has profound implications when it comes to interpreting the lipid profile.
The equation states that LDL equals total cholesterol minus HDL and subtracted from this is triglycerides divided by 5 (see below).
LDL (calculated) = Total Cholesterol – HDL – SG 5
So when you give your blood the numbers for total cholesterol, HDL and TG are put into the equation and voila, your LDL comes out. Now look very carefully at how simple this equation is. It’s simple, right? What did you notice? There are many subtractions and a fraction. This fraction is important because when you divide the same number into a lower number, what do you think happens? For example, divide one hundred by five. You get twenty, of course. Now divide fifty, a lower number, by five. Now we have ten. So dividing a lower number by the same number results in a LOWER number. It’s pretty simple.
This lower number is particularly important because it is subtracted from another part of the equation. So what happens if you subtract a lower number from something? Unless you’re dealing with negative integers, you’ll get a HIGHER number. As an example, subtract five from ten. The result is five. Now subtract two, a number less than ten and eight is the result. Eight is higher than five. It’s still not that complicated.
Now let’s digress a bit and talk about what total cholesterol really means. We haven’t done this yet and it really is quite simple. Total cholesterol is just that, total cholesterol. We arrive at total cholesterol by adding HDL, LDL (remember LDL is calculated here, not measured), and VLDL (IDL doesn’t even get an honorable mention for some reason). So the equation looks like this:
Total Cholesterol = HDL + LDL + VLDL; where VLDL = SG 5
Now, what do you think happens to total cholesterol if you increase, say, LDL? That’s right, the total goes up. What happens if the VLDL increases? Uh huh, the total goes up. Wait a minute. What happens if HDL goes up? Bingo, so will your total cholesterol.
As a very, very important side note, this is why when you start cutting your carbs and eating more fat and cholesterol, your total cholesterol can go up. That is why it is very important NOT to panic. A very common scenario is the following; a patient realizes that the correct way to eat is to eat fewer carbohydrates and eat more fat, protein, and cholesterol. They go through their lab work and their doctor notes that while HDL is up dramatically, total cholesterol is up as well. Then the patient is admonished against what he did. They tell them those diets are bad for you. They are then told to start a low-fat, low-cholesterol diet and guess what; when they check their numbers in a few months, they are so bad that they end up taking cholesterol-lowering drugs.
This is an absolute tragedy. The doctor who advises his patient to abandon a low-carb, higher-fat, higher-cholesterol, higher-protein diet because total cholesterol went up, but so did HDL, is displaying extreme ignorance of total cholesterol. This should never happen, but nevertheless it happens every day. Every day in almost every doctor’s office around the world. But wait, it gets even worse.
Remember I said it’s important to know that LDL is calculated, not measured. The reason this is important is because when HDL goes up, total cholesterol can go up. And when TGs go down, you end 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’s right, it will go up. Again, look at the equation. What do you think you’ll get when you subtract higher HDL from higher total cholesterol? And remember, total cholesterol is higher because HDL is higher. Let’s do some math together to figure it out.
Subtract thirty-five, a common HDL to see, from a total cholesterol of two hundred and thirty. You get one hundred and ninety-five. Now subtract fifty, a fairly common increase to see if you’re eating the right way, from a total cholesterol of two hundred and sixty-five. Now we have two hundred and fifteen. Do a little 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 end up with a higher number. Now when we subtract a smaller number from this larger number, the result will be a larger number. The smaller number we are subtracting results from the fact that TGs are lower when we reduce our carbohydrate 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 that we are subtracting from the higher number that we arrived at above.
So the bottom line of the calculated LDL value when your total cholesterol and HDL go up and your triglycerides go down, IS THAT LDL GOES UP BECAUSE OF THE WAY IT’S CALCULATED! We want HDL to go higher. We want your blood fats to be lower. When this happens, it will often increase LDL. No, it doesn’t happen in everyone, but it does in almost everyone and it’s solely due to the way LDL is calculated.
Now guess what happens when you walk into your doctor’s office after spending three months eating properly? Your HDL will be higher, which is great, but this can cause your total cholesterol to rise. Your triglycerides will be lower, which is awesome because that’s what you want. But your LDL will be higher. Again, based on the formula the lab uses to calculate LDL, your LDL will be higher when your HDL is higher and your TG is lower.
When your doctor reads your lab report, do you really think he or she is going to say, “Wow, great, everything is fantastic!” Unlucky. All your doctor sees is elevated total cholesterol and elevated LDL. They panic, meaning your doctor, and immediately want to put you on cholesterol-lowering medication. But wait a minute; if they’re so interested in lowering calculated LDL, we can do it by raising their TG or lowering their HDL—exactly what we don’t want to do.
Just to bring everyone up to date. I think the latest guidelines say to keep your LDL below 70 if you have risk factors for heart disease. I have difficulty with this concept because we are using calculated LDL and not measuring it directly. Sure, cholesterol-lowering drugs work, but too often I see well-trained cardiologists freaking out because they can’t get the calculated LDL below seventy, or even one hundred. And they will just keep pushing the dosage higher and higher and higher. If you would just stop and think about the process, you would realize that for the vast majority of people this approach will not work. Why? Because your patients’ TGs may be low and their HDLs may be where they should be, according to the calculation, the LDL will never go below 70.
But one cannot really dwell on these documents 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 push the accepted drugs for the treatment of cholesterol. But this would still be defined as ignorance, wouldn’t it? And who do we blame for the millions of people who die each year because of this?
The lipid profile numbers to pay attention to are just HDL and TG. What I like to use is the TG to HDL ratio. Keep this serving to or less than two and you’ll be sitting pretty. If it goes above two, be careful, because now you’re not only looking at an increased risk of heart disease, but diabetes and cancer as well. Two other diseases that we will talk about shortly.
Now we come to chapter six.
Men occasionally stumble over the truth, but most of them just get up and run like nothing happened. -Winston Churchill