Small LDL Particles: Bullies looking for trouble
An Interview with lipidologist, Dr. Tara Dall
Small LDL is the #1 most common lipid/lipoprotein abnormality causing coronary plaque. It’s also among the most ignored. Track Your Plaque interviews lipid expert, Dr. Tara Dall, for an in-depth discussion about this important problem.
TYP: How common is the small LDL pattern in the
U.S. Is it a big problem? Why do people get it?
Dr. Dall: We are seeing more and more people with small LDL as we
face an epidemic of obesity. Obesity, especially abdominal obesity
(certain to be present when waist circumference is larger than 35 inches
in a woman, 40 inches in a man, though can be present even without
girths this large), is closely associated with the metabolic syndrome.
This is not a problem just for adults but is now very prevalent in
children as we face an obesity epidemic in our youth as well.
I treat families with genetic lipid disorders but see an equal if not
greater number of children with obesity and lipid disorders associated
with excess weight. Obesity related lipid disorders are more responsive
to lifestyle changes than are the genetic lipid disorders.
If a child has a both a genetic disorder and metabolic syndrome or
obesity, they are at very high risk for early heart disease. I fear we
will see an epidemic of heart disease and type 2 diabetes in 20 and 30
year olds in the next decade if we don't address these risk factors
aggressively with lifestyle changes.
With 67 million obese adults in the U.S. today, small LDL is a pattern I
see every day. In fact, I’d estimate that around half or more of the
adults I see have the small LDL pattern to some degree.
TYP: What makes small LDL so bad?
Dr. Dall: Why is small LDL such a bad player? Small LDL particles
are more likely to become oxidized, a highly-damaging form of LDL, and
contribute to plaque formation. There are many properties of small LDL
that make it more likely to cause disease. Small dense LDL more readily
enters the arterial wall and triggers a cascade of inflammation.
Inflammation is a key component to plaque development.
I tell my patients that, though small LDL is bad, it’s even worse
because of the company it keeps. People with small dense LDL particles
also typically have high triglycerides and low HDL, both criteria for
the metabolic syndrome, all of which we know puts them at high risk for
cardiovascular disease.
TYP: When should small LDL be suspected?
Dr. Dall: As a lipidologist, I see patients with relatively
normal LDL cholesterol that are still having cardiac events. That’s when
I order advanced lipid testing that reveals the small LDL pattern. I
find that these patients actually have very elevated risk based on large
number of small dense LDL and increased number of LDL particles.
Other patients that we frequently see "hidden risk" from small LDL are
in patients with diabetes, metabolic syndrome, polycystic ovarian
syndrome, and those with low HDL or high triglycerides. These patients
benefit from advanced lipid testing that can identify small LDL.
We are focusing on small dense LDL particles versus large bouyant LDL
particles, but what may be even more important is how many particles you
have. If you have a very elevated number of large particles, you are at
risk. This is seen primarily in patients with a specific LDL receptor
defect and diagnosis of Familial Hypercholesterolemia (FH).
Increased numbers of LDL particles are strongly associated with
increased coronary heart disease risk. Multiple clinical trials
demonstrate that increased LDL particle number is far more strongly
associated with heart disease outcomes and sub-clinical coronary disease
than is LDL cholesterol.
(Editor’s Note: The only company that directly measures LDL
particle number is Liposcience in Raleigh, North Carolina. Contact them
through www.liposcience.com .)
TYP: Why does plain old LDL cholesterol fail to fully identify
risk in many people?
Dr. Dall: Let's discuss the “disconnect” between LDL cholesterol
and number of LDL particles.
Cholesterol and triglycerides are fats and don't float in the blood
stream by themselves. They need to be carried in spheres of protein that
allow them to be soluble in plasma. When I discuss this with patients, I
describe these spheres as being different based on proteins on the
outside of the spheres’ contents. Thus, we have spheres (particles)
called HDL, LDL, VLDL or IDL. When we measure your cholesterol, we are
measuring all the cholesterol that is inside all the HDL particles or
LDL particles. But we have no idea how many particles you have.
People with low number of particles (<1000 nmol/l by NMR) but an LDL of
130 mg/dl are at much less risk for heart disease than those with LDL of
130 mg/dl and large number of small particles (>1000 nmol/l by NMR). It
takes more small particles to carry the same amount of cholesterol as it
would take large particles. Thus, most patients with increased number of
particles also have small dense particles.
I use advanced lipid testing as my routine lipid panel in most patients.
This allows me to get a much more accurate assessment of a patients risk
for heart attack or stroke. I am able to be more aggressive or less
aggressive based on this testing. I also use other advanced tests such
as hsCRP, LpPLA2 (PLAC), and lipoprotein(a) to assess risk. These may be
topics for another discussion.
TYP: Do you have any specific approaches to reduce or eliminate
small LDL?
 |
Want to read the rest of this Track Your Plaque Special Report?
Already a member? CLICK HERE to log-in. |
Copyright 2006, Track Your Plaque.