Guidelines for healthy cholesterol levels on available on medical websites such as WebMD, Drugs.com and Heart.org by the American Heart Association. Doctors determine overall cholesterol levels after examining a blood test known as a lipoprotein profile, according to WebMD.
Lipoprotein profiles include total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides, notes WebMD. Doctors may interpret an LDL cholesterol reading of 190 milligrams per deciliter of blood or more as very high, and health professionals may recommend medication and dietary changes to lower that number. Triglycerides of 500 or more are "very high," and these substances may increase someone's risk of coronary artery disease.
Patients with levels of HDL cholesterol at 60 milligrams per deciliter or higher generally develop less atherosclerosis, says Drugs.com. Individuals with 40 milligrams per deciliter or less of HDL cholesterol have a greater risk of developing cholesterol deposits in arteries. Usually, doctors consider an LDL cholesterol level of less than 100 to be ideal.
A total cholesterol level of less than 180 milligrams per deciliter represents an optimal score, according to the American Heart Association. Doctors calculate this number by adding HDL cholesterol, LDL cholesterol and 20 percent of the triglyceride total. Higher HDL levels combined with lower LDL levels may help maintain a healthier heart. The American Heart Association advocates people over the age of 20 have their cholesterol levels checked every four to six years.