LDL levels aren't measured according to normalcy or age but fall into one of six categories for adults, notes the American Heart Association. A desirable LDL level for an adult of any age is 100 mg/dL or less. One hundred to 129 mg/dL is also good and considered near optimal.
An LDL level of 130 to 159 mg/dL is considered borderline high, while an LDL level of 160 to 189 mg/dL is considered high risk, states the American Heart Association. Any LDL level over 190 mg/dL is considered very high risk. It is recommended that all adults have their cholesterol levels checked every five years or more often for men over 45 and women over 50, according to Heart Disease Research Institute.