Let Dr. Friedewald rest in peace
Peter had been told that his LDL cholesterol was
good, ranging from 90–120 mg/dl on several panels over the years. So
it was a surprise when his heart scan score proved high at 423. A
more intensive look through lipoprotein analysis (NMR) revealed that
his true, measured LDL cholesterol was 203 mg/dl—far higher.
Billions of dollars of drug company revenues rely on it. Yet it is a
fabrication, a number that is not measured, but calculated. The
calculation is crude, generally unreliable, and an outdated
simplification, a calculation that was necessary 40 years ago
because of limited access to laboratory testing.
That number is LDL cholesterol, the number one target for drug
manufacturers, the topic of dozens of daily TV commercials, and the
financially most successful drug class in history. If there’s one
number most people know about their health, it’s their LDL
cholesterol.
Imagine you’d like to know your blood pressure. Rather than
measuring it, I take a look at you, measure your height and weight,
consider sex and age, and tell you, “According to my calculation,
your blood pressure is 145/80”. Perhaps it’s in the ballpark of true
blood pressure, but would be satisfied with this assumption?
Probably not. But that’s what LDL cholesterol is.
Why a calculation?
In the 1960s, doctors struggled with the concept of
cholesterol and its relationship to heart disease. It became clear that
higher levels of cholesterol were predictive of heart disease. It was
also became clear that the low-density fraction of cholesterol, or LDL,
was superior to total cholesterol for predicting heart attack.
Total blood cholesterol was easily measurable in the 1960s. LDL was not.
So, Dr. Friedewald, a noted lipid researcher at the National Institutes
of Health, proposed an easy method to calculate LDL cholesterol from
total choleseterol, HDL, and triglycerides:
LDL cholesterol = Total cholesterol – HDL cholesterol – triglycerides/5
This simple manipulation would put LDL cholesterol into the hands of the
practicing physician and the American public. Dr. Friedewald recognized
that this calculation only represented an approximation of LDL
cholesterol. Calculated LDL was thrown off, sometimes substantially, by
any abnormal rise in triglycerides or reduction in HDL. But it served
its purpose at a time when most doctors hadn’t even heard of
cholesterol, the public was still sold on whole milk and “farm-fresh”
butter, and Chesterfields were the cigarette choice of most doctors.
The world has since changed. Most doctors have heard about cholesterol
and, along with the public, have been drowned in drug company marketing
for cholesterol-reducing drugs. Most people with some level of common
sense and health awareness no longer use butter or whole milk, and no
longer believe that the brand of cigarette you choose can be healthy.
But most physicians still use Dr. Friedewald’s original calculation for
LDL cholesterol. When you get an LDL cholesterol from your clinic,
doctor, or hospital, >99% of the time it is obtained using Dr.
Friedewald’s calculation.
Is it because there’s nothing better available? No, it’s not. There’s
two reasons why your neighborhood primary care physician or cardiologist
is still using this dinosaur of testing called LDL:
1) The lag in science to practice is 20 years. Accept that most primary
care doctors are 20 years behind the times on many issues, LDL
cholesterol included.
2) Insurance companies vigorously discourage testing beyond conventional
lipids. It’s more expensive to get better information.
The array of objections we get from insurance companies is
mind-boggling. Insurance companies declare these tests “experimental”,
“unproven”, unendorsed by standard guidelines, not approved by some
internal committee, or some other outlandish excuse for denying
coverage. We’ve heard them all. It would be funny if human life and
finances weren’t at stake.
What’s better than calculated LDL?
What are the tests that are superior to Dr.
Friendewald’s calculated LDL? There are several, listed here in order of
best to worst:
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Copyright 2006, Track Your Plaque.