Hypercholesterolemia
The content of the article:
- Causes
- Forms of hypercholesterolemia
- Signs
- Diagnostics
- Treatment of hypercholesterolemia
- Diet for hypercholesterolemia
- Prevention
- Consequences and complications
Hypercholesterolemia (hyperlipidemia, hyperlipoproteinemia, dyslipidemia) is a pathological condition in which there is an abnormal increase in blood cholesterol levels. Hypercholesterolemia is one of the main risk factors for the development of atherosclerosis and cardiovascular pathology. In this case, the risk increases in proportion to the increase in the concentration of low-density lipoproteins in the patient's blood.
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Cholesterol is an organic compound that is found in the cell membranes of all living organisms, except non-nuclear ones. Cholesterol is not soluble in water, but soluble in organic solvents and fats. Approximately 80% of cholesterol is produced by the human body itself, the rest enters the body with food. The compound is necessary for the production of steroid hormones by the adrenal glands, the synthesis of vitamin D, and also ensures the strength of cell membranes and regulates their permeability.
Atherogenic, i.e., contributing to the formation of cholesterol, lipid metabolism disorders include an increase in blood levels of total cholesterol, triglycerides, low density lipoproteins and a decrease in high density lipoproteins.
Causes
The main reason for the development of primary hypercholesterolemia is a genetic predisposition. Familial hypercholesterolemia is a genetically heterogeneous autosomal dominant disorder that is associated with the inheritance of mutant genes encoding the low density lipoprotein receptor. To date, four classes of low-density lipoprotein receptor mutations have been identified, which result in impaired synthesis, transport, binding and clustering of low-density lipoproteins in the cell.
The secondary form of hypercholesterolemia develops against the background of hypothyroidism, diabetes mellitus, obstructive liver diseases, heart and vascular diseases, due to the use of a number of drugs (immunosuppressants, diuretics, beta-blockers, etc.).
Risk factors include:
- male gender;
- age over 45;
- excessive amounts of animal fats in the diet;
- overweight;
- lack of physical activity;
- exposure to stress.
Forms of hypercholesterolemia
Hypercholesterolemia is subdivided into primary and secondary.
In accordance with the classification by the World Health Organization, the following forms of hypercholesterolemia are distinguished:
- type I (hereditary hyperchylomicronemia, primary hyperlipoproteinemia) - the frequency of occurrence is 0.1%, occurs with insufficient lipoprotein lipase or defects in the activator protein of this enzyme, manifested by an increase in the level of chylomicrons that transport lipids from the intestine to the liver;
- type IIa (hereditary hypercholesterolemia, polygenic hypercholesterolemia) - the frequency of occurrence is 0.2%, it can develop against the background of inappropriate nutrition, as well as be polygenic or hereditary, manifesting itself as xanthomas and early onset of cardiovascular pathology;
- type IIb (combined hyperlipidemia) - the incidence of 10%, occurs due to excessive production of triglycerides, acetyl-CoA and apolipoprotein B, or slow clearance of low density lipoproteins; accompanied by an increase in blood triglycerides in the composition of very low density lipoproteins;
- type III (hereditary dys-beta-lipoproteinemia) - the frequency of occurrence is 0.02%, can develop with homozygosity for one of the isoforms of apolipoprotein E, is manifested by an increase in the level of intermediate density lipoproteins and chylomicrons;
- type IV (endogenous hyperlipemia) - the frequency of occurrence is about 1%, manifested by an increase in the concentration of triglycerides;
- type V (hereditary hypertriglyceridemia) - manifested by an increase in the level of very low density lipoproteins and chylomicrons.
The more rare forms of hypercholesterolemia that are not included in this classification include hypo-alpha-lipoproteinemia and hypo-beta-lipoproteinemia, the frequency of which is 0.01–0.1%.
Familial hypercholesterolemia can be homozygous or heterozygous.
Signs
Hypercholesterolemia is a laboratory indicator that is determined during a biochemical blood test.
In patients with hypercholesterolemia, xanthomas often occur - skin neoplasms of altered cells, which are compacted nodules, inside which lipid inclusions are contained. Xanthomas accompany all forms of hypercholesterolemia, being one of the manifestations of lipid metabolism disorders. Their development is not accompanied by any subjective sensations, in addition, they are prone to spontaneous regression.
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Xanthomas are classified into several types:
- eruptive - small yellow papules, localized mainly on the thighs and buttocks;
- tuberous - they look like large plaques or tumors, which, as a rule, are located in the buttocks, knees, elbows, on the back of the fingers, face, scalp. Neoplasms can have a purple or brown hue, a reddish or cyanotic border;
- tendon - localized mainly in the area of the extensor tendons of the fingers and Achilles tendons;
- flat - most often found in the folds of the skin, especially on the palms;
- Xanthelasmas are flat xanthomas of the eyelids, which are yellow plaques raised above the skin. More often found in women, not prone to spontaneous resolution.
Another manifestation of hypercholesterolemia is cholesterol deposits along the periphery of the cornea (lipoid arch of the cornea), which have the appearance of a white or grayish-white rim. The lipoid arch of the cornea is more common in smokers and is almost irreversible. Its presence indicates an increased risk of developing coronary heart disease.
With the homozygous form of familial hypercholesterolemia, a significant increase in blood cholesterol levels is observed, which is manifested by the formation of xanthomas and lipoid arch of the cornea already in childhood. In puberty, such patients often experience atheromatous lesions of the aortic orifice and stenosis of the coronary arteries of the heart with the development of clinical manifestations of ischemic heart disease. In this case, acute coronary insufficiency is not excluded, which can cause death.
The heterozygous form of familial hypercholesterolemia, as a rule, remains unnoticed for a long time, manifesting itself as cardiovascular insufficiency already in adulthood. Moreover, in women, the first signs of pathology develop on average 10 years earlier than in men.
An increase in blood cholesterol levels provokes the development of atherosclerosis, which, in turn, is manifested by vascular pathology (mainly atherosclerotic lesions of the blood vessels of the lower extremities, but damage to the cerebral, coronary vessels, etc. is also possible).
Diagnostics
The main method for detecting hypercholesterolemia is a biochemical blood test. In this case, in addition to the lipidogram, the content of total protein, glucose, uric acid, creatinine, etc. is determined. In order to identify concomitant pathology, a general blood and urine test, immunological diagnostics are prescribed, and a genetic analysis is performed to identify the possible cause of hypercholesterolemia. In order to exclude hypothyroidism, a study of the level of thyroid hormones (thyroid-stimulating hormone, thyroxine) in the blood is carried out.
On objective examination, attention is paid to cholesterol deposits (xanthomas, xanthelasmas, lipoid arch of the cornea, etc.). Blood pressure in patients with hypercholesterolemia is often elevated.
To diagnose vascular changes, they resort to instrumental diagnostics - angiography, magnetic resonance angiography, Doppler sonography, etc.
Treatment of hypercholesterolemia
Drug therapy for hypercholesterolemia consists in the appointment of statins, bile acid sequestrants, fibrates, inhibitors of cholesterol absorption in the intestine, and fatty acids. When concomitant arterial hypertension is detected, drugs that normalize blood pressure are used.
In the course of lipid metabolism correction, xanthomas usually regress. If this does not happen, they are removed surgically, or by cryodestruction, laser or electrical coagulation.
In homozygous patients with familial hypercholesterolemia, drug therapy is usually ineffective. In such a situation, they resort to plasmapheresis with a two-week interval between procedures. In severe cases, liver transplantation is required.
An important component of the normalization of fat metabolism is the correction of excess body weight and a healthier lifestyle: good rest, adequate physical activity, smoking cessation, and diet.
Diet for hypercholesterolemia
The basic principles of a diet for hypercholesterolemia:
- reducing the amount of fat in the diet;
- reduction or complete elimination of high-cholesterol foods;
- limiting saturated fatty acids;
- an increase in the proportion of polyunsaturated fatty acids;
- eating a lot of plant fiber and complex carbohydrates;
- replacement of animal fats with vegetable;
- limiting the use of table salt to 3-4 grams per day.
It is recommended to include white poultry meat, veal, beef, lamb, fish in the diet. Choose lean meats (tenderloin and fillets preferred), remove skin and fat. In addition, the diet should contain fermented milk products, coarse bread, cereals, vegetables and fruits. Eggs can be eaten, but their number is limited to four per week.
Fatty meats, sausages, offal (brain, liver, kidneys), cheese, butter, coffee are excluded from the diet.
Food is prepared in gentle ways that reduce the fat content in ready-made dishes: boiling, stewing, baking, steaming. If there are no contraindications (for example, intestinal diseases), you should increase the content of fresh vegetables, fruits and berries in the diet.
Prevention
In order to prevent the development of disorders of fatty and other types of metabolism, it is recommended:
- balanced diet;
- maintaining a normal body weight;
- rejection of bad habits;
- sufficient physical activity;
- avoidance of mental stress.
Consequences and complications
Hypercholesterolemia can lead to the development of atherosclerosis. In turn, this causes vascular damage, which can have various manifestations.
Violation of normal blood circulation in the lower extremities contributes to the formation of trophic ulcers, which in severe cases can lead to tissue necrosis and the need for limb amputation.
When the carotid arteries are damaged, cerebral circulation is impaired, which is manifested by a disorder of the cerebellar function, memory impairment, and can lead to a stroke.
When atherosclerotic plaques are deposited on the wall of the aorta, it becomes thinner and loses its elasticity. Against this background, a constant blood flow leads to stretching of the aortic wall, the resulting expansion (aneurysm) has a high risk of rupture with the subsequent development of massive internal hemorrhage and a likely fatal outcome.
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Anna Aksenova Medical journalist About the author
Education: 2004-2007 "First Kiev Medical College" specialty "Laboratory Diagnostics".
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
