Cholesterol – high density lipoprotein (HDL)

The concentration of cholesterol (in chemistry - cholesterol) in the blood is one of the key markers of the state of lipid (fat) metabolism in the body. In clinical hematology, analysis of HDL and LDL cholesterol is performed using a colorimetric, photometric or electrophoretic method.

The study is called a lipidogram, otherwise the lipid profile (status) of the patient. If prescribed by a doctor, indicators of cholesterol metabolism can be included in a detailed biochemical analysis of venous blood.

What are HDL and LDL in cholesterol metabolism?

Cholesterol refers to fat-containing alcohols. The substance is concentrated in cell membranes and serves to protect cells. The body needs cholesterol as a participant in the most important processes that support life:

• hormonal synthesis (steroid and sex hormones);
• production of bile acids;
• absorption of fat-soluble vitamins (A, E, D);
• maintaining pregnancy;
• interaction between the spinal cord and brain.

Cholesterol is divided into two types: exogenous, entering the body with animal fats (butter, meat, milk, etc.); endogenous, produced by liver cells (hepatocytes) inside the body.

Reference: The share of exogenous cholesterol is 20% of the total amount.

Cholesterol, like fat, cannot move through the bloodstream on its own. Once in the blood, its molecules combine with apoprotein proteins and other lipids (triglycerides, phospholipids), forming courier lipoproteins of different densities. The less protein there is in lipoproteins, the lower their density.

20% of cholesterol enters the body with food, and 80% is produced by liver cells

Triglycerides (TG or TG) are formed from fatty foods and are stored in fatty tissues. Essentially, this is the body's lipid reserves, used to replenish energy. Phospholipids are a special type of fat that is not synthesized by the body; they consist of fatty acids, polyhydric alcohols and phosphoric acid and are necessary for the construction of cell membranes.

Types of lipoproteins

Five main types of lipoproteins are involved in cholesterol metabolism.

Accepted classification of lipoproteins and main functions

LDL and VLDL are positioned as “bad” cholesterol. When moving through arteries and capillaries, they “cling” to microdamages in the intima (the inner layer of the vascular wall) and settle.

A cholesterol stain forms inside the vessel, on the basis of which a cholesterol plaque is subsequently formed, which becomes the cause of atherosclerosis. HDL is called “good” cholesterol because it escorts low-density and very low-density lipoproteins out of blood vessels, preventing them from sticking to the intima.

Components of lipoproteins in percentage

The table shows that chylomicrons and low-density lipoproteins contain the most fat (triglycerides).

Walnuts, almonds and other nuts

Benefits of nuts

Walnuts, almonds and other nuts can improve your cholesterol levels. Rich in mono- and polyunsaturated fatty acids, walnuts also help support vascular health.

Eating a handful of almost any type of nut (almonds, hazelnuts, peanuts, pecans, pine nuts, pistachios, walnuts) daily can reduce your risk of heart disease. When choosing nuts, make sure that they are without added salt or sugar.

All nuts are high in calories, so a handful (40-45 g) will be enough. To avoid overeating and weight gain, replace foods rich in saturated fat with nuts. For example, instead of cheese, meat or croutons, add a handful of walnuts or almonds to your salad.

Lipid profile parameters

The laboratory measurement value for total cholesterol and its fractions is mmol/l. Indicators included in the lipid profile:

Normal blood cholesterol levels

• OX (Cho);
• HDL;
• LDL;
• VLDL;
• HM;
• TG;
• KA (IA).

TC – total cholesterol level. KA – coefficient (otherwise, index) of atherogenicity. When assessed by electrophoretic method, fractions are divided:

• alpha lipoproteins or HDL;
• beta lipoproteins – LDL;
• prebeta lipoproteins – VLDL.

The CA value is a laboratory marker that reflects the degree of danger of atherosclerotic changes in blood vessels. It is calculated using the formulas: KA = (LDL + VLDL) / HDL or IA = (Cho – HDL) / HDL.

Ways to reduce low-density lipoproteins

Elevated LDL requires dietary adjustments, giving up bad habits, and sometimes its level decreases only with appropriate drug therapy.

First of all, it is necessary to adjust the menu to exclude harmful products from it. Healthy foods that can lower bad cholesterol include:

• chicken or turkey breast,
• veal,
• herring,
• salmon,
• tuna,
• mackerel,
• low-fat sour cream,
• yogurt,
• vegetables and fruits,
• durum wheat pasta,
• legumes,
• mineral water.

Medicines that affect cholesterol levels in the body should only be taken on the advice of a doctor.

There are also foods that you should absolutely not eat, as the level of bad cholesterol will increase even more:

• fatty meats,
• sausages,
• crabs,
• squid,
• egg yolk,
• cream and processed cheeses,
• fried vegetables,
• confectionery,
• carbonated drinks.

You can reduce bad cholesterol levels not only by adjusting your diet. This will also be facilitated by following the following recommendations:

• Try to avoid stressful situations. Increasingly, doctors agree that stress provokes the appearance of atherosclerotic plaques on blood vessels.
• Physical activity. Three 30-minute workouts per week are enough to start reducing LDL.
• Quit smoking and strong alcohol.

Traditional methods for reducing bad cholesterol

Traditional medicine also offers ways to reduce bad cholesterol. There are many recipes, the most popular are:

• Hawthorn infusion – 2 tbsp. l. flowers pour 3 tbsp. boiling water and boil for 10 minutes, leave until cool and take 1 glass three times a day half an hour before meals.
• Sweet clover officinalis. Take 4 tsp. herbs, pour 3 tbsp. boiling water, boil for 10 minutes and leave for 2 hours. Drink 3 times a day 20 minutes before meals.
• Rowan. 2 tbsp. l. fruits pour 600 ml of water and leave, drink 1 tbsp. before main meals.
• Pumpkin. It is necessary to include pumpkin seeds in the diet in an amount of at least 40–50 grams per day.

Sometimes patients need drug therapy to lower cholesterol. For this purpose, drugs of two groups are used: statins, or cholesterol absorption inhibitors, and lipid-lowering drugs. It is prohibited to take such drugs on your own, as they can cause significant harm to the body if the dosage is chosen incorrectly. If medications are prescribed, they should be taken according to the dosage regimen.

Controlling cholesterol levels in middle-aged people is very important. Timely measures to reduce bad cholesterol or increase good cholesterol can reduce the likelihood of heart attack and stroke and improve a person’s quality of life.

Preparing to donate blood for a lipid profile

Preliminary preparation for analysis is necessary to obtain accurate results. 2-3 days before the prescribed procedure, it is recommended to refuse foods rich in animal fats and alcoholic beverages (including weak alcohol), and stop taking any medications other than those necessary for medical reasons.

The day before the procedure:

• reduce physical activity;
• limit sugar intake.

Blood sampling is performed strictly on an empty stomach. The fasting regime should be at least 8 hours.

Normal lipid status

The norms for total cholesterol do not depend on gender. For men and women from 20 to 45 years old, the indicators should fall within the range of 3.2-5.2 mmol/l. If the result is equal to or greater than 6.7 mmol/l, then the patient is diagnosed with hypercholesterolemia.

At values ​​below the norm of 3.2 mmol/l – hypocholesterolemia. Both disorders are considered pathologies. Reference values ​​for high-density and low-density lipoproteins differ by gender and age category.

Normal indicators

The values ​​of triglycerides and very low density lipoproteins for men and women are identical:

• TG – 0.41-1.8 mmol/l;
• VLDL – 0.26-1.04 mmol/l.

For the atherogenicity coefficient, only inflated values ​​are of diagnostic value. The higher the KA, the higher the risk of atherosclerosis.

CA norm table

Deviation from normal levels of LDL and HDL

Non-standardized lipoprotein values ​​should be considered only in conjunction with triglyceride values ​​and the level of total cholesterol in the blood. When HDL cholesterol is elevated with normal levels of TC and other fractions, this indicates good lipid metabolism. An unfavorable combination is when the level of LDL and TC is increased, and the level of HDL is decreased.

The following indicators accompany chronic diseases:

• hepatobiliary system (hepatosis, cirrhosis, cholecystitis, cholangitis, etc.);
• renal apparatus (pyelonephritis, nephritis, etc.);
• endocrine system (diabetes mellitus, hypothyroidism);
• cardiovascular system (hypertension, atherosclerosis, coronary heart disease, pericarditis, myocarditis, endocarditis, etc.).

As well as some autoimmune and oncological pathologies. If there are no such diagnoses, then the cause may be an unhealthy lifestyle:

• unhealthy diet (predominance of animal fats in the diet, deficiency of vegetables and fruits);
• alcohol and nicotine addiction;
• sedentary lifestyle;
• long-term stress.

In this case, the results of the lipid profile should be regarded as a high risk of developing atherosclerosis and heart disease. With a decrease in HDL, “bad” cholesterol settles on the inner wall of blood vessels, forming cholesterol spots, from which atherosclerotic plaques eventually form. Such growths inside the vessel block blood flow, which causes heart attack, stroke, and dry gangrene of the lower extremities.

Hypocholesterolemia is also harmful to the body. Lack of cholesterol threatens hemorrhagic stroke, destruction of cell membranes, anemia (anemia), osteoporosis, neuropsychological disorders and depression.

With cholesterol deficiency, the synthesis of sex hormones is disrupted. As a result, libido decreases, men experience problems with potency, women's menstrual cycles become disrupted, and there is a risk of infertility.

Lipid profile, screening

Reference values

For people over 18 years of age, normal cholesterol levels are less than 5.0 mmol/L.
However, this number is arbitrary, since the doctor must take into account other indicators of the lipid spectrum (LDL and triglyceride levels will be important). Decoding indicators

The result of a lipid spectrum study should be interpreted depending on the purpose of the examination and the specific clinical situation, in conjunction with the data of a medical examination and the results of other studies.

Total cholesterol

– an indicator reflecting the totality of all cholesterol fractions circulating in the blood.
Cholesterol itself is insoluble in the blood. To transport cholesterol in the body, complex compounds are formed by binding to protein molecules. Such complexes are called lipoproteins
.

Depending on the particle size and their functions, high-density lipoproteins (HDL, HDL-C), low-density lipoproteins (LDL, LDL-C), very low-density lipoproteins (VLDL, VLDL-C), cholesterol not associated with high-density lipoproteins are isolated density (non-HDL), and a number of other substances.

Why is cholesterol needed in the body? Cholesterol is formed in the liver, intestines and skin, and also comes from food of animal origin. It is impossible to completely avoid consuming cholesterol in food for a number of reasons. Firstly, it is one of the main building materials for all cells. Secondly, cholesterol is actively involved in the formation of various hormones, including sex hormones. Cholesterol is also important for the digestion process - it is involved in the formation of bile in the liver. Cholesterol is a precursor to vitamins D, which, in particular, help strengthen bones.

High density lipoproteins (HDL)

- the only fraction of cholesterol that is called “good”, “healthy” cholesterol. HDL significantly reduces the risk of developing atherosclerosis. These molecules remove excess “bad” cholesterol from the body by transporting it from the tissues to the liver, where the cholesterol is converted into bile acids and then released into the intestines.

If the HDL result is below reference values, the risk of developing atherosclerosis and serious cardiovascular pathology increases significantly. Also, low levels of HDL can be observed in the following conditions: familial dyslipidemia, chronic liver diseases with symptoms of bile stagnation (cholestasis), chronic kidney disease, diabetes mellitus, obesity, long-term use of certain medications (beta blockers, diuretics, progestins, androgens). A diet rich in simple carbohydrates or saturated fatty acids also helps lower HDL levels.

Low-density lipoproteins (LDL)

are considered a “harmful”, “atherogenic” fraction of cholesterol, that is, they provoke the development of atherosclerosis. With this disease, the risk of developing life-threatening conditions such as stroke, acute myocardial infarction, coronary heart disease, and heart failure increases significantly.

A decrease in LDL cholesterol does not play a significant role in the diagnosis of diseases. A significant decrease in the level of LDL in the blood is possible with severe liver diseases, cancer, infections, burns, hyperthyroidism, and malnutrition.

Very low density lipoproteins (VLDL)

also belong to the “bad” fraction of cholesterol, since they serve as the main precursors of LDL. VLDL transports fats from the liver to body tissues and actively participates in the formation of atherosclerotic plaques. In people with diabetes, VLDL accelerates the development of atherosclerosis.

VLDL and LDL can increase in many diseases: obesity, diabetes mellitus, chronic kidney disease, hypothyroidism, chronic pancreatitis, systemic lupus erythematosus, hereditary disorders of fat metabolism, pregnancy, alcohol abuse.

A decrease in VLDL concentration has no diagnostic value.

Intermediate density lipoproteins (IDL)

– a transitional form between HDL and LDL, part of the group of atherogenic (“harmful”) cholesterol fraction. The study is used in conjunction with other lipid profile indicators to assess the risk of developing atherosclerosis.

Lipoprotein (a) (LP(a))

- a molecule similar to LDL, also classified as atherogenic and having a protein component. The study of Lp(a) is carried out when treatment for dyslipidemia is ineffective and is a genetic risk factor for the development of cardiovascular diseases, regardless of the level of other atherogenic fractions of cholesterol.

Cholesterol not bound to high-density lipoprotein

(non-HDL), is the sum of all atherogenic cholesterol fractions (LDL + VLDL + LDLP + LP(a)). This indicator allows for better control of treatment for mild to moderate increases in triglyceride levels, since in such a situation the measurement and calculation of LDL is less accurate.

Triglycerides

They are one of the main sources of energy in the body. They come from food and are formed in the intestines, liver and adipose tissue. With an excess intake of calories and a sedentary lifestyle, adipose tissue deposits triglycerides as an energy source.

Transport of triglycerides in the body is carried out using protein complexes, mainly in the form of very low density lipoproteins (VLDL).

An increase in the level of triglycerides in the blood plasma often occurs when the principles of a healthy diet are violated, with obesity, alcohol abuse, diabetes mellitus, various kidney diseases, and liver diseases. In rare cases, an increase in triglyceride levels may be a consequence of hereditary disorders of lipid metabolism (in such situations, the study results exceed the upper limit of values ​​tens of times). Along with this, an increase in the concentration of triglycerides, like other types of fats in the blood, leads to an increased risk of developing cardiovascular diseases.

Reduced triglyceride levels are not significant in diagnosis. It is most often found in intestinal pathologies associated with malabsorption of nutrients, during a period of strict diet, fasting, and hyperthyroidism.

Atherogenic index

– the ratio of non-HDL cholesterol to HDL cholesterol. This indicator is calculated in a laboratory or by a doctor to assess the risk of cardiovascular disease. An increase in the atherogenic index indicates an increased risk of pathology.

For additional diagnosis of atherosclerotic changes and damage to internal organs, use:

1. Biochemical blood test - indicators of liver function: total protein, albumin, alanine aminotransferase (ALAT), aspartate aminotransferase (AST), bilirubin and its fractions.

Results

HDL and LDL are the most important participants in cholesterol metabolism, the amount of which in the blood must meet certain standards. Low-density lipoproteins supply the body's cells with cholesterol, which is produced by the liver. High-density lipoproteins cleanse blood vessels of excess fat, preventing the development of atherosclerosis.

Dyslipidemia, otherwise an imbalance of LDL and HDL, accompanies a number of chronic diseases or is a consequence of unhealthy eating behavior, bad habits, and physical inactivity. You can check your fat metabolism levels by donating blood for a special test - a lipid profile.