When referring to LDL and HDL, you're actually looking at your cholesterol levels. Both low-density lipoprotein (LDL) and high-density lipoprotein (HDL) can contribute to your overall cholesterol level, which begs the question "What's considered 'good' levels of LDL and HDL?"

Low-Density Lipoprotein

With low-density lipoprotein, you're dealing with "bad" cholesterol, so you really want a relatively low level of this in your blood. Under 100 mg/dL (milligrams of cholesterol per deciliter) is desired.

High-Density Lipoprotein

With high-density lipoprotein, you're dealing with "good" cholesterol, so you want a higher level of this in your blood. Anything over 60 mg/dL is optimal.

High Cholesterol

If your LDL cholesterol reaches anywhere above 159 mg/dL, you're said to have high blood cholesterol. In regards to HDL cholesterol, anything below 40 mg/dL puts you at greater risk of developing heart disease.

Complications

An LDL or HDL number outside the healthy range can lead to not only heart disease, but also coronary artery disease, atherosclerosis (narrowing of the arteries), heart attack and stroke.

Contributing Factors

Diets high in fat and cholesterol can greatly contribute to greater levels of LDL in your bloodstream, but diets lacking in fruits and vegetables can lead to low levels of HDL. Besides your diet, excess weight, sedentary lifestyles, smoking, high blood pressure and genetics can contribute to an increase in LDL and decrease in HDL.

Treatment

Since diet contributes to both LDL and HDL levels, treatment often begins with a change in diet, incorporating more fruits, vegetables, whole grain and low-fat dairy into your eating habits. From there, you may need medications, such as statins, fibrates, cholesterol absorption inhibitors and niacin.

Source:

Mayo Clinic: High Blood Cholesterol

Cleveland Clinic: High Cholesterol