The causes of increase and decrease in high density lipoprotein

Reducing the concentration of HDL-cholesterol less than 0.9 mmol / l is associated with an increased risk of atherosclerosis. Epidemiological studies have shown an inverse relationship between the concentrations of HDL-C and the prevalence of IHD. The definition of HDL-cholesterol helps identify the risk of developing coronary artery disease. Reducing the concentration of HDL-Cs for every 5 mg / dL, or 0.13 mmol / L below the average leads to an increased risk of developing CHD by 25%.

Elevated HDL-C concentration is regarded as an anti-atherogenic factor.

An increased level of HDL is considered if it is more than 80 mg / dL (> 2.1 mmol / l).

Elevated levels of HDL reduce cardiovascular risk; however, high levels of HDL, caused by some primary genetic abnormalities, may not protect against cardiovascular diseases due to concomitant metabolic disorders of lipids and metabolic disorders.

The primary causes are single or multiple genetic mutations, which result in hyperproduction or decreased HDL removal. Secondary causes of high levels of HDL are chronic alcoholism with an outcome in cirrhosis of the liver, primary biliary cirrhosis, hyperthyroidism and the use of certain medications (eg, glucocorticoids, insulin, phenytoin). In the case of unexpected clinical findings of high HDL-C levels in patients not taking lipid-lowering medications, a diagnostic assessment of the secondary causes of this condition development should be made without delay, with the mandatory measurement of ACT, ALT and TSH; A negative evaluation of the result indicates possible primary causes of dyslipidemia.

Deficiency of cholesterol ester of carrier protein (SBTR) is a rare autosomal recessive hereditary pathology due to the mutation of the CETP gene. CETP facilitates the transfer of cholesterol esters from HDL to other lipoproteins, and thus, the deficiency of CETP leads to a decrease in LDL cholesterol and a delayed elimination of HDL. Clinically, patients have no symptoms or signs of disease, but they have a HDL-C> 150 mg / dl. There is no reduction in cardiovascular risk. Treatment is not required.

Family hyperalipopoproteinemia is an autosomal dominant hereditary condition caused by various unknown sciences and known genetic mutations, including those that lead to hyperproduction of apolipoprotein A-1 and apolipoprotein C III type. Pathology is usually detected by chance when the HDL levels in the plasma are> 80 mg / dl. Patients do not experience any other clinical symptoms or signs. Treatment is not required.

Currently, the concentration of HDL-C in serum below 0.91 mmol / l is considered as an indicator of high risk of coronary heart disease, while a level above 1.56 mmol / l plays a protective role. To determine the tactics of treatment, it is important to simultaneously assess the concentration in the serum of total cholesterol and HDL-C. If a patient's HDL-C-cholesterol level is lower (less than 0.91 mmol / L) and total cholesterol is normal, exercise, stop smoking and reduce body weight are most effective in preventing IHD. With an increase in the total cholesterol concentration and a decrease in HDL-C (less than 0.91 mmol / L), medical intervention programs should be aimed at lowering the total cholesterol level with special diets or, if necessary, with drug therapy.

Having determined the content in the blood of HDL-cholesterol, it is possible to calculate the cholesteric coefficient of atherogenicity (К _хс ): К _хс = (General ХС-HDL-XC) / HDL-XC. К _хс actually reflects the ratio of the content in the blood of atherogenic LP to antiatherogenic. This coefficient is no more than 1 in newborns, in healthy men of 20-30 years it reaches 2.5, in healthy women of the same age it is 2.2. In men 40-60 years old without clinical manifestations of atherosclerosis K _xc is from 3 to 3.5. In individuals with IHD, he is more than 4, often reaching 5-6. It is noteworthy that К _{хс is} relatively low in long-livers: in individuals over 90 years it does not exceed 3. К _хс more accurately reflects the favorable and unfavorable combination of LP in terms of the risk of development of IHD and atherosclerosis.

When analyzing the results of the study, it should be taken into account that an increase or decrease in the content of HDL-cholesterol is possible in a number of diseases or conditions.

Diseases and conditions in which the concentration of HDL-C in the blood can change

Increased values	Low values
Primary biliary cirrhosis of the liver	Diabetes
Chronic hepatitis	Kidney and liver diseases
Alcoholism	GLP type IV
Other chronic intoxications	Acute bacterial and viral infections

However, the use of only HDL-XC indices to assess the risk of developing atherosclerosis can give potentially incorrect diagnostic information, so its values should be assessed in comparison with the concentration of total cholesterol and LDL-C.