Hypercholesterolemia is an increase in the concentration of total cholesterol in the blood plasma above 5 mmol / l. The causes of this laboratory abnormality can be varied - from nutritional errors and obesity to endocrine disorders and genetic diseases. Most often clinically asymptomatic. In some cases, xanthomas (nodular formations on the skin in the area of the joints), xanthelasmas (yellowish plaques in the eyelids), and a lipoid arch on the cornea are observed. The level of cholesterol is examined in the venous blood before meals. Correction is carried out with the help of diet and prescription of statins.
Most often in clinical practice, the classification of hypercholesterolemia according to Friderikson is used, which is based on the division according to the predominance of one or another cholesterol fraction:
By origin, hypercholesterolemia is divided into:
1. Primary . This form, in turn, is divided into:
2. Secondary . High blood cholesterol, which develops against the background of certain diseases, endocrine disorders or medications.
According to the degree of increase in the level of cholesterol in the blood, there are:
Cholesterol values can also exceed the norm in healthy people. For example, changes in the balance of female sex hormones during pregnancy cause an increase in cholesterol levels. After childbirth, the indicators return to normal. In case of improper preparation before taking a biochemical blood test (eating fatty foods on the eve of blood donation), cholesterol is higher than normal.
This group of diseases is called "hereditary (familial) hypercholesterolemia". They are caused by mutations in genes encoding the expression of lipoprotein receptors (LDLR, ApoB-100, PCSK9) or the lipoprotein lipase enzyme. This leads to a violation of catabolism and absorption of lipoproteins by cells, as a result of which the concentration of cholesterol in the blood begins to increase significantly.
A distinctive feature of familial forms of hypercholesterolemia is the detection of very high cholesterol levels (in homozygous patients it can reach 2 mmol / l) from early childhood (5-7 years). All this is associated with the rapid progression of atherosclerosis and the development of serious cardiovascular complications already at the age of 20-25. Aggressive lipid-lowering therapy is required to normalize cholesterol levels.
Xanthelasma on the eyelids - a sign of hypercholesterolemia
Excess weight ranks first among the etiological factors of hypercholesterolemia and accounts for more than 90% of all its cases. The pathogenesis of the influence of excess weight on cholesterol levels is as follows. Adipocytes secrete a large amount of biologically active substances that reduce the sensitivity of cells to insulin, insulin resistance is formed.
As a result, lipolysis and the release of free fatty acids (FFA) are activated. From the excess of FFA entering the liver, a large amount of VLDL is synthesized - one of the fractions of cholesterol. Hypercholesterolemia increases slowly and is directly proportional to the degree of obesity, it can gradually return to normal with weight loss, but with a long course it becomes irreversible.
The cause of hypercholesterolemia can be kidney diseases accompanied by nephrotic syndrome: the initial stage of glomerulonephritis, diabetic or hypertensive nephropathy, nephropathy with multiple myeloma. An increase in cholesterol levels is associated with the loss of carrier proteins and enzymes involved in lipid catabolism (lecithin-cholesterol acetyltransferase, lipoprotein lipase) in the urine.
The severity of hypercholesterolemia correlates with the degree of proteinuria. After specific therapy of the underlying disease and relief of the nephrotic syndrome, the cholesterol level usually normalizes, however, in some cases it remains elevated for a long time, which may require additional therapeutic measures to prevent the progression of atherosclerosis.
A special place in the structure of the causes of hypercholesterolemia is occupied by diseases of the endocrine system. Insufficiency or excess production of one or another hormone causes significant changes at different stages of lipid metabolism.
An increase in serum cholesterol levels can be observed in diseases of the liver and biliary tract, accompanied by intra- or extrahepatic cholestasis (bile stasis). Hypercholesterolemia is caused by impaired utilization of cholesterol for the production of bile acids. Its degree correlates with the severity of cholestasis.
The highest rates are observed in primary sclerosing cholangitis, primary and secondary biliary cirrhosis, less pronounced in parenchymal liver diseases (alcoholic, viral hepatitis, fatty degeneration of the liver). Elimination of cholestasis leads to a fairly rapid normalization of cholesterol.
Laboratory hypercholesterolemia is detected in the study of venous blood. In addition to the concentration of total cholesterol, the determination of its fractions and triglycerides is more informative. For differential diagnosis, the patient's age and other anamnestic data are important - medication intake, the presence of close relatives with a confirmed familial form of hypercholesterolemia. To clarify the etiological factor, the following examination is carried out:
For drug correction of hypercholesterolemia, different groups of drugs are prescribed.
If hypercholesterolemia is detected, it is imperative to consult a doctor to find out the cause of this laboratory phenomenon and select the right treatment. Much attention is paid to the fight against the underlying disease (immunosuppressive therapy for nephrotic syndrome, hormone replacement therapy for hypothyroidism, choleretic therapy for cholestasis), since its elimination can lead to normalization of cholesterol levels without additional intervention.
Non-drug methods for correcting hypercholesterolemia include a complete cessation of smoking, limiting alcohol consumption. Also, patients suffering from obesity, in order to reduce body weight, it is necessary to follow a diet with a decrease in the proportion of animal fats in the diet (butter, fried meat, sausages) and an increase in vegetable fats (vegetables, seafood), fruits and whole grains, regularly perform various physical exercises.
For the medical correction of hypercholesterolemia, the following drugs are used:
One of the prerequisites for the effective treatment of hypercholesterolemia is the normalization of body weight. Patients with morbid obesity (body mass index above 40), especially in combination with type 2 diabetes, with the failure of conservative methods, bariatric surgery is indicated - gastric banding, gastric bypass or resection.
If hypercholesterolemia is caused by cholestasis due to gallstone disease, surgical removal of the gallbladder (cholecystectomy) is performed. Patients with Itsenko-Cushing's disease undergo endoscopic transnasal adenomectomy (removal of pituitary adenoma). With Itsenko-Cushing's syndrome, bilateral adrenalectomy is used.
Hypercholesterolemia leads to the deposition of cholesterol on the walls of arterial vessels, the formation of atherosclerotic plaques, narrowing of the lumen and deterioration of the blood supply to organs and tissues. It has the main clinical significance for the coronary and cerebral arteries. Therefore, a long-term increase in cholesterol concentration is an unfavorable prognostic factor for cardiovascular diseases and is associated with such formidable complications as acute myocardial infarction and acute cerebrovascular accident.