Recent guidelines have, therefore, advocated the use of direct methods for measurement of LDL wherever possible. It may be useful to measure all lipoprotein subfractions (VLDL, IDL, LDL, and HDL) when assessing hypercholesterolemia and measurement of apolipoproteins and lipoprotein (a) can also be of value. Genetic screening is now advised if a form of familial hypercholesterolemia is suspected. Classification
Classically, hypercholesterolemia was categorized by lipoprotein electrophoresis and the Fredrickson classification. Newer methods, such as "lipoprotein subclass analysis", have offered significant improvements in understanding the connection with atherosclerosis progression and clinical consequences. If the hypercholesterolemia is hereditary (familial hypercholesterolemia), more often a family history of premature, earlier onset atherosclerosis is found. Screening method
The U.S. Preventive Services Task Force in 2008 strongly recommends routine screening for men 35 years and older and women 45 years and older for lipid disorders and the treatment of abnormal lipids in people who are at increased risk of coronary heart disease. They also recommend routinely screening men aged 20 to 35 years and women aged 20 to 45 years if they have other risk factors for coronary heart disease. In 2016 they concluded that testing the general population under the age of 40 without symptoms is of unclear benefit.In Canada, screening is recommended for men 40 and older and women 50 and older. In those with normal cholesterol levels, screening is recommended once every five years. Once people are on a statin further testing provides little benefit except possibly to determine compliance with treatment.
Insufficient blood supply to the legs may manifest as calf pain when walking, while in the intestines it may present as abdominal pain after eating a meal.Some types of hypercholesterolemia lead to specific physical findings. For example, familial hypercholesterolemia (Type IIa hyperlipoproteinemia) may be associated with xanthelasma palpebrarum (yellowish patches underneath the skin around the eyelids), arcus senilis (white or gray discoloration of the peripheral cornea), and xanthomata (deposition of yellowish cholesterol-rich material) of the tendons, especially of the fingers. Type III hyperlipidemia may be associated with xanthomata of the palms, knees and elbows. Causes
Hypercholesterolemia is typically due to a combination of environmental and genetic factors. Environmental factors include weight, diet, and stress. Loneliness is also a risk factor. Diet
Diet has an effect on blood cholesterol, but the size of this effect varies between individuals.A diet high in sugar or saturated fats increases total cholesterol and LDL. Trans fats have been shown to reduce levels of HDL while increasing levels of LDL.A 2016 review found tentative evidence that dietary cholesterol is associated with higher blood cholesterol. As of 2018 there appears to be a modest positive, dose-related relationship between cholesterol intake and LDL cholesterol. Medical conditions and treatments
A number of other conditions can also increase cholesterol levels including diabetes mellitus type 2, obesity, alcohol use, monoclonal gammopathy, dialysis therapy, nephrotic syndrome, hypothyroidism, Cushings syndrome and anorexia nervosa.