There are no symptoms of high cholesterol; the only way to discover that blood cholesterol levels are out of range is via a blood test. Mayo Clinic recommends that everyone have a baseline cholesterol test at age 20 and then every 5 years or sooner after that to keep a check on cholesterol levels.
Cholesterol levels can be affected by a variety of things, including diet. Foods that contain cholesterol, trans fat and saturated fat can cause elevated levels of cholesterol. Being obese or overweight can lower good cholesterol levels, as can inactivity. Cholesterol starts to go up after age 20, so age plays a role in cholesterol levels. People with a family history of high cholesterol can also have higher than normal levels, according to WebMD.
In order to test cholesterol levels, a blood test called a lipid panel is used. This test measures the levels of fat that are found in the blood and returns a total cholesterol level and levels of HDL and LDL cholesterol.
High cholesterol is a marker for an increased risk of stroke and heart attack. Along with blood pressure, status of diabetic or nondiabetic, race, age, sex and smoking status, cholesterol is used by the medical profession to determine risk of disease and premature death.