Cholesterol (cont.)
Is lowering LDL cholesterol enough?
Unfortunately, the prevention and treatment of atherosclerosis are more
complicated than just lowering LDL cholesterol levels. LDL cholesterol reduction
is only half of the battle against atherosclerosis. Individuals who have normal
or only mildly elevated LDL cholesterol levels can still develop atherosclerosis
and heart attacks even in the absence of other risk factors such as cigarette
smoking, high blood pressure, and diabetes mellitus. Additionally, successfully
lowering elevated LDL cholesterol levels cannot always prevent atherosclerosis
and heart attacks. In many clinical trials to lower LDL cholesterol, there were
patients who adhered to their assigned diets, faithfully took their
cholesterol-lowering medications, and successfully lowered their LDL cholesterol
to target levels, yet still suffered progressive atherosclerosis and heart
attacks. It is clear that while lowering LDL cholesterol below NCEP target
levels is an important step, there are other factors involved.
What is lipoprotein (a), (Lp(a)) cholesterol?
Lipoprotein (a) (Lp(a)) is an LDL cholesterol particle that is attached to a
special protein called apo(a). In large part, a person's level of Lp(a) in the
blood is genetically inherited. Elevated levels of Lp(a) (higher than 20 mg/dl
to 30 mg/dl) in the blood are linked to a greater likelihood of atherosclerosis
and heart attacks in both men and women. The risk is even more significant if
the Lp(a) cholesterol elevation is accompanied by high LDL/HDL ratios.
Certain diseases are associated with elevated Lp(a) levels. Patients on
chronic kidney dialysis and those with nephrotic syndromes (kidney diseases that
cause leakage of blood proteins into the urine) tend to have high levels of
Lp(a).
There are many theories as to how Lp(a) causes atherosclerosis although
exactly how Lp(a) accumulates cholesterol plaques on the artery walls has not
been well defined. Clinical trials conclusively proving that lowering Lp(a)
reduces atherosclerosis and the risk of heart attacks have not been conducted.
Currently, there is no international standard for determining Lp(a) cholesterol
levels and commercial sources of Lp(a) testing may not have the same accuracy as
research laboratories. Therefore, specifically measuring and treating elevated
Lp(a) cholesterol levels are not widely performed in this country.
How can Lp(a) cholesterol levels be reduced?
Most lipid-lowering medications such as statins, Lopid, and cholestyramine
have a limited effect in lowering Lp(a) cholesterol levels. Estrogen has been
shown to lower Lp(a) cholesterol levels by approximately 20% in women with
elevated Lp(a) cholesterol. Estrogen can also increase HDL cholesterol levels
when given to postmenopausal women. Additionally, nicotinic acid (Niacin or
Niaspan) in high doses has been found to be effective in lowering Lp(a)
cholesterol levels by approximately 30%.
Last Editorial Review: 4/13/2005
- Statins - Read about statins, cholesterol lowering medications like Levacor, Zocor, Pravachol, Lipitor, Crestor, and more. Side effects, drug interactions, and patient information is also provided.
- Homocysteine - Read about the test for homocysteine levels in the blood. High levesl of homocysteine include increased risk of heart attacks, strokes, blood clots, and Alzheimer's disease.
- Diabetes - Learn about type 1 and 2 diabetes (Diabetes Mellitus) symptoms including increased urination, thirst, weight loss, fatigue, nausea, vomiting, skin infections, and blurred vision. Causes and diagnosis information is provided in the information.
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