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Cholesterol:
How Low Can it Go?
By: Dr. Stefanie Kelley
"What is your particle
size?" "How low are your LDL's?"
No, these are not the new pick up lines for the "over 65" crowd.
These are the new questions in the trend to monitor cholesterol in adults
more closely. No longer is monitoring cholesterol a concern for those
65 and over, high cholesterol is becoming a concern for adults starting
at age 20, and even in children.
The National Cholesterol
Education Program (NCEP) released the latest Adult Treatment Panel III
(ATP III) which recommends more aggressive treatment of high cholesterol
and identifies new levels of cholesterol as major risk factors for heart
disease. Total cholesterol levels less than 200mg/dL continue to be desirable.
High density lipoprotein (HDL) cholesterol is now recommended to be over
40mg/dL. The main change in the ATP III recommendations is that low density
lipoprotein (LDL) cholesterol should be less than 130mg/dL or optimal
LDL less than 100mg/dL. For more information on the ATP III at a glance
go to www.nhlbi.nih.gov/guidelines/cholesterol/atglance.htm.
The elevation of low
density lipoprotein (LDL) cholesterol is now a major risk factor for the
development of coronary heart disease (CHD). Lowering LDL cholesterol
is one of the main recommendations of the ATP III. This change focuses
on lowering the low density lipids (LDL) cholesterol to:
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below 100mg/dL for
persons with CHD
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below 130mg/dL for
persons with 2 or more CHD risk factors
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below 160 mg/dL
for persons with 0-1 CHD risk factors |
The presence of clinical
atherosclerotic disease that places a person at high risk for CHD includes:
clinical CHD, symptomatic carotid artery disease, peripheral arterial
disease, and abdominal aortic aneurysm. Major risk factors for CHD include:
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elevated LDL >
160mg/dL
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low HDL cholesterol
< 40mg/dL
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cigarette smoking
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hypertension (BP
> 140/90 mmHg) OR currently on antihypertensive medication
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family history of
premature CHD (CHD in male first degree relative <55 years OR CHD
in female first degree relative < 65 years)
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Age (men 45 years
or older OR women 55 years or older) |
The ATP III now recommends
a fasting complete lipoprotein profile (total cholesterol, LDL cholesterol,
HDL cholesterol, and triglycerides) as the preferred initial test. LDL
cholesterol can be estimated using the Friedewald equation in which lab
values are expressed in mg/dL:
LDL cholesterol = [Total cholesterol] - [HDL cholesterol] - [Triglycerides]/5.
The complete lipoprotein analysis is suggested to be performed every 5
years for persons 20 years and older. If a person continues to be at low-risk
for CHD, cholesterol screening can occur every 5 years. If CHD risk increases,
the lipoprotein analysis is suggested to be a guide for clinical management.
The ATP III does not make recommendations for cholesterol screening in
children. However, the National Heart, Lung, and Blood Institute (NHLBI)
recommends that children of "high-risk" families (parents with
total cholesterol > 240 or a parent or grandparent that has CHD at
55 years or younger) should be screened.
As the LDL cholesterol
takes on a greater concern for health care providers and patients, further
understanding of the LDL measurement is important. The LDL cholesterol
lab value is most accurate when the person has been fasting for 9 to 12
hours. The LDL lab value measures the amount of low density lipoproteins
that carry cholesterol. This form of cholesterol has been found to cause
athrosclerotic plaques in blood vessels that contribute to heart disease
and stroke. The LDL measurement is a representation of a concentration
of potentially athrogenic cholesterol particles, apolipoprotein B (apoB).
These athrogenic particles can be small and dense OR soft and fluffy.
The small and dense athrogenic particles are sticky and are thought to
be more often associated with atherosclerosis than the large fluffy particles.
Measuring the apoB is a newer method for predicting risk of developing
heart disease. Knowing particle size could allow health care providers
to initiate therapeutic lifestyle changes (TLC) early in order to prevent
plaque formation. More information on measuring apoB can be found at www.americanheart.org/presenter.jhtml?identifier=3016380.
Clinical management of
elevated cholesterol and LDL cholesterol requires multidimensional treatment.
Initiating therapeutic lifestyle changes (TLC) is the first line treatment
of elevated cholesterol. ATP III recommends the TLC Diet:
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Saturated fat <7%
of calories, cholesterol < 200 mg/day
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Increased soluble
fiber (10-25g/day) and plant stanols/sterols 2g/day
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Saturated fats, which
are the main dietary cause of high cholesterol, are found in animal foods
(beef, veal, pork, poultry, and dairy products made from whole milk) and
some plant foods (tropical (palm, coconut) oils and cocoa butter). Hydrogenated
fats that raise cholesterol are found in most margarine and shortening.
Use hydrogenated fats only if there are fewer than 2 grams of saturated
fat per tablespoon. Polyunsaturated and monounsaturated fats may lower
cholesterol and can be used in limited amounts in place of saturated fats.
Weight management and increased physical activity are key components included
in lifestyle changes. Drug therapy for lowering cholesterol should be
considered if after 3 months there is no change in LDL levels or additional
CHD risk factors are assessed.
The NCEP ATP III recommendations
and continued efforts by researchers, health care providers, and patients
represent the ongoing effort to reduce the morbidity and mortality of
elevated blood cholesterol. As the body of knowledge on CHD increases
cholesterol management continues to be a dynamic medical challenge.
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