When LDL levels are too high, LDL cholesterol can build up in the artery walls, eventually causing blockages that cause heart attacks, explains Mayo Clinic. Most people should aim for an LDL level below 130 milligrams per deciliter to reduce their risk of heart disease.
An LDL cholesterol level between 130 and 159 milligrams per deciliter is considered borderline high, while a level between 160 and 189 milligrams per deciliter is considered high, according to Mayo Clinic.
Patients whose LDL levels are 190 milligrams per deciliter or higher are placed in the "very high" category.
LDL is also known as "bad" cholesterol, and patients whose levels are too high can take several actions to reduce them, explains Mayo Clinic. Quitting smoking, eating more soluble fiber, losing weight, and getting at least 30 minutes of exercise per day all help reduce LDL cholesterol levels. When lifestyle changes do not lower LDL cholesterol enough, prescription medications may be used to lower them further.
Those at a high risk for heart disease may be advised by their physicians to aim for an LDL cholesterol level as low as 100 or even 70 milligrams per deciliter, notes Mayo Clinic. LDL levels are measured with a simple blood test called a lipid panel, which also measures HDL, or "good" cholesterol levels, as well as total cholesterol and triglyceride levels.