The New ABCs of Cholesterol Health
Just when patients were getting comfortable
with the concept of "good" and "bad" cholesterol levels, doctors
are readying another kind of heart-health test.
The good news, according to some
experts, is that the so-called ApoB test is an even better way to
figure out if your arteries are in danger of clogging.
There are a few caveats, says Dr.
Gerald S. Berenson, a professor of medicine at Tulane University
in New Orleans. ApoB tests are more expensive than traditional cholesterol
tests. And researchers haven't developed firm guidelines on how
to interpret them. Even so, it's "very valuable" for doctors to
test the ApoB levels of their patients, he says.
Just as constricted water hoses burst
under pressure, blocked arteries can rupture, leading to a heart
attack or stroke. For decades, doctors have relied on cholesterol
tests to determine whether people are at risk of developing atherosclerosis,
also known as hardening of the arteries.
The problem is that traditional cholesterol
tests only provide part of the picture of what's going on inside
arteries, says Dr. Steven Haffner, a professor of medicine at the
University of Texas Health Science Center in San Antonio. In essence,
cholesterol tests only measure the number of leaves on trees in
a forest, not the total number of trees, which is more important,
In a study released last October
in the journal Circulation, Haffner and his colleagues reported
that blood levels of apolipoprotein B (ApoB) appear to be a better
measure of heart disease risk than normal LDL ("bad") cholesterol
levels. That study examined the results of blood tests and compared
them to other measures of heart risk among 1,522 patients.
ApoB tests measure a component of
LDL cholesterol, "the stuff that gets into the arterial wall as
part of the atherosclerosis process," Berenson says.
"It is a better predictor in general"
of heart disease, and could reveal problems in patients who have
normal cholesterol levels, Haffner says.
ApoB also appears to be more related
to potential risks factors such as insulin resistance than traditional
LDL cholesterol, Haffner says. If patients have high ApoB levels,
they can lower them by taking statin drugs, the same medications
that are used to lower cholesterol.
ApoB tests are not yet routine, however.
Haffner says they can be useful in patients at high risk of heart
But at least one doctor isn't quite
ready to embrace ApoB tests.
It's true that LDL cholesterol levels
can miss the full threat of clogged arteries, says Dr. Alistair
Fyfe, chief of cardiology at Medical City Dallas Hospital. But ApoB
tests don't do a much better job, he says, because they can't pinpoint
how much cholesterol is floating around. Other types of new tests
can measure the size of cholesterol particles and will make ApoB
tests "obsolete," he says.
When the costs of these particle-size
tests become reasonable, they "will wipe everything else off the
map," Fyfe says. He adds that other tests will also give doctors
a better handle on which drugs to use.
Berenson says both kinds of tests
-- those that measure ApoB levels and particle sizes -- are important,
but the ApoB tests remain much cheaper. By combining traditional
cholesterol tests with ApoB tests, he says, doctors can still get
an "excellent measure" of what's going on in your arteries.
To learn more about ApoB testing,
visit the University
of California, San Francisco. Get the lowdown on cholesterol
figures from the National
Heart, Lung, and Blood Institute.
Reference Source 101