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Several factors may contribute to high blood cholesterol, and most common is a diet high in saturated fats and, less so, high in cholesterol. The cause could also be a lack of exercise, which may increase LDL (“bad” cholesterol) and decrease HDL (“good” cholesterol). Family history could predispose some people to have a higher risk of high cholesterol, especially if they have a direct male relative aged under 55 or a female relative aged under 65 affected by coronary heart disease. Being overweight may increase LDL cholesterol and decrease HDL cholesterol as well. We should also consider age and sex, since cholesterol generally rises slightly with increasing age, and men are more likely to develop hypercholesterolemia than women are. Drinking alcohol excessively also contributes to this problem.
Rarely, high cholesterol levels develop because of a condition that runs in the family called a lipid disorder, or familial hypercholesterolemia. Some other health conditions such as poorly controlled diabetes, certain kidney and liver diseases, and an under-active thyroid gland may also cause cholesterol levels to rise. Some medicines such as beta-blockers, steroids or thiazides may also affect blood lipid levels and cause hypercholesterolemia.
How does diet affect blood cholesterol?
Only about 20% of cholesterol comes directly from the diet, while the other 80% is produced by the liver. However, a diet high in saturated fats and cholesterol can cause the liver to produce more LDL cholesterol. The amount of diet-based influence on cholesterol levels varies from person to person, and is probably an inherited characteristic. Some people who eat high-fat diets have high cholesterol levels. At the same time, others may have normal or low cholesterol levels.
Who should have a cholesterol test?
Anyone who has any cardiovascular disease, such as coronary heart disease, peripheral vascular disease, or stroke, should have his or her cholesterol measured by a doctor. Anyone, even children, with a family history of familial hypercholesterolemia should have cholesterol measured. Anyone aged 35 or over should consider having their cholesterol measured if they have some risk factors for CHD, or coronary heart disease. These risk factors are family history of early heart disease, diabetes, high blood pressure, or smoking.
Diagnosis of hypercholesterolemia
Having a high cholesterol level does not cause symptoms, so most people find out they have high cholesterol when they have their blood cholesterol measured as part of a medical check-up. Alternatively, a doctor could identify hypercholesterolemia after diagnosing other health problems, such as heart disease.