Atherogenic index – what is it? What is the norm?
Author Ольга Кияница
The atherogenic coefficient (CA) is calculated using certain cholesterol fractions. Under favorable conditions, “bad” cholesterol goes into a bound state, that is, turns into low-density lipoproteins.
The atherogenic coefficient is used in diagnostics most often when precise determination of the state of fat metabolism is required.
Together with the atherogenic coefficient, an atherogenic plasma index is often determined. The use of these indicators today is strongly recommended for early diagnosis and preventive measures to control various cardiovascular diseases, including IHD.
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Characteristics of atherogenicity
Assessment of atherogenic cardiovascular risk is important in the treatment of dyslipidemia associated with antiretroviral therapy (ART). Most often, the Castelli Risk Index (CRF), atherogenic plasma index (AIP) and atherogenic index (CA) are the most useful indicators as predictors of cardiovascular risk (CVD).
Atherogenicity is the ratio between harmful and beneficial forms of cholesterol, to determine which biochemical blood test is used.
Lipids of low and very low density (respectively, LDL and VLDL) are considered to be harmful or “bad” cholesterols .Their dimensions are so large that they cannot penetrate into the tissues, but it also turns out to circulate in the blood for a long time, so they are deposited on the inner walls of the vessels. This leads to the definition of atherosclerotic plaque, which in turn contributes to the formation of other pathologies. For this reason, “bad” fats are also called atherogenic.
“Good” cholesterol is the popular definition of high-density lipoprotein (HDL). Their molecules also have large sizes, but at the same time HDL are involved in the transport of fatty alcohol (a harmful compound) to the liver cells (hepatocytes). Therefore, it is believed that high-density lipoproteins are important in the functioning of the body and therefore are useful.
To determine the concentration of lipids in the blood used various types of laboratory tests. Recently, more and more published clinical guidelines calling for indicators of CVD risk predictors to be taken into account. In particular, if necessary, the level of the atherogenicity coefficient is determined, which best indicates the degree of atherogenicity in a particular person.
CA indicator allows you to identify the degree of risk in the following diseases:
- Pathology of the liver.
- Thyroid disease.
Additionally, CA is required to assess a person’s condition during a routine examination and to determine the effectiveness of a drug exposure.
Atherogenic coefficient calculation
The level of spacecraft is determined using biochemical analyzes. In particular, the concentration of total cholesterol and HDL (anti-atherogenic lipids) in the blood is determined. Additionally, other indicators of fat metabolism can be calculated, which makes it possible to assess the situation on a wider scale. A similar study is referred to as lipid profile analysis:
- Total cholesterol is a generalized definition for all forms of lipoprotein, both “good” and “bad”.
- High-density lipoproteins - are considered anti-atherogenic, because they prevent the formation of atherosclerotic plaques.
- Low and very low density lipoproteins and - directly involved in the development of atherosclerosis.
- Triglycerides are esters from the discharge of higher fatty acids, also belong to atherogenic factors, because after the release, VLDL is transported in the liver.
Some indicators from lipid profile analysis are used to calculate CA, for which a simple formula is used:
KA = (total cholesterol - HDL) / HDL
Subtracting HDL from total cholesterol allows you to find out the concentration of LDL and VLDL. Thus, almost all indicators from the analysis of the lipid profile, except for triglycerides, take part in the calculation of CA. By the way, they can significantly complicate the research.
In some laboratory institutions, the calculation of spacecraft is carried out according to a slightly modified formula:
KA = (LDL + VLDL) / HDL
Here, the LDL is separately determined by their precipitation during the analysis. In addition, the concentration of triglycerides is calculated and the resulting value is equal to the amount of VLDL. If spacecraft are calculated with direct participation of triglycerides (TG), then the following formula is used:
KA = LDL + TG / 2.2
As can be seen from the above calculations, the values of CA mainly depend on total cholesterol, which includes LDL and VLDL, as well as antiatherogenic HDL.
What does increasing atherogenicity mean
The normal value of a spacecraft is 2-3 conventional units . If the index is determined in the region of 3-4, then this indicates a possible dyslipidemia, which, in the absence of correction of everyday life, can achieve a high level of atherogenicity.
Increased CA is considered if this indicator is more than 4. In such cases, there is a very high probability that the walls of blood vessels will gradually become blocked by atherogenic lipoproteins. They have nowhere to go from the bloodstream, so an atherosclerotic plaque is formed.
The increase in CA is observed in all different ways. One, as they say, everything is possible and at the same time the indicator does not change significantly. Others need only a minor error in the diet, so that CA can grow several times.This may be due to the presence of other risk factors that have a direct effect on the level of lipoproteins in the blood. In particular, attention should be paid to the following predisposing situations:
- Family predisposition to various disorders of fat metabolism.
- Emotional overstrain on an ongoing basis.
- Determination of extra pounds.
- The presence of bad habits by type of smoking, alcoholism, drug addiction or substance abuse.
- Disorders of the endocrine glands, such as diabetes.
- Insufficient physical activity.
It should be noted that the increase in CA is often observed in conditions such as pregnancy or menstruation, since during these periods there is a significant hormonal activity. Also, “fast” fasting can lead to the release of fat reserves in the blood, which will immediately lead to changes in laboratory parameters.
With a high probability of the formation of atherosclerosis and similar diseases to it, the doctor may prescribe the necessary drugs, statins or hormones. Their use is often associated with the development of serious side effects, but most often of the two evils choose the lesser.
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Atherogenic rate in women
The female body during the period of hormonal activity is able to cope well with atherogenic lipoproteins, not allowing them to exceed the permissible level. But this is only if a healthy lifestyle is not disturbed and the woman is not pregnant or does not celebrate red days.
It is believed that in women, the spacecraft normally should not exceed 3.2, then the risk of developing atherosclerosis will be minimal.
The situation changes markedly in the postmenopausal period. Then significantly increases the risk of developing cardiovascular diseases compared with women in premenopause due to an increase in the atherogenic lipid profile.
The researchers confirmed the presence of atherogenic indicators correlation with the following factors:
- Body mass index.
- Systolic blood pressure.
- Diastolic blood pressure [1 - Gita Khakurel, Rajat Kayastha, Sanat Chalise, Prabin K Karki Atherogenic Index of Plasma in Postmenopausal Women, 2018].
These data do not give the right to women under the age of 50 not to follow the diet or violate other rules of a healthy lifestyle. Such recommendations are relevant for all people of any age and gender who wish to preserve their health.
Male atherogenic index
KA in men may be slightly higher than in women. The definition of a high level of spacecraft similarly indicates a significant risk of developing CVD.
Normally, for males, spacecraft should not exceed 3.5 conventional units.
Due to the greater predisposition of men to various violations of the rules of a healthy lifestyle, this category of the population often develops CVDs. In view of this, it is necessary to carefully follow the existing recommendations to reduce the risk of atherosclerosis, which will allow the body to be kept in the right form both up to 50 years old and after.
It should be pointed out that a low level of spacecraft is not associated with any painful conditions, therefore, as a rule, they do not pay attention to a decrease in the index. Sometimes the results of spacecraft will be lower than normal, especially if a person practices low-cholesterol nutrition, takes a type of statin, or engages in professional sports.
Recommendations to reduce atherogenicity
Medical management of patients with increased atherogenicity first involves changing risk factors — for example, by stopping smoking and practicing a restrictive diet. Prevention usually consists of proper nutrition, exercise, quitting smoking and maintaining a healthy weight.
Up to 90% of cardiovascular diseases can be prevented by avoiding established risk factors [2 - McGill HC, McMahan CA, Gidding SS (March 2008). "Preventing heart disease in the 21st century: Implications of the Pathobiological Detergent of Atherosclerosis in Youth (PDAY) study". Circulation. 117 (9): 1216–27].
Changes in nutrition can help prevent the development of many diseases associated with high CA. Preliminary evidence suggests that a diet containing dairy products does not affect or reduce the risk of CVD.
A diet based on fruits and vegetables significantly reduces the risk of CVD and death. There is also evidence that a Mediterranean diet can improve the functioning of the heart and blood vessels. However, some researchers suggest that the Mediterranean diet is often more beneficial than food with a low content of fatty substances. It provides long-term changes in CVD risk factors (for example, lowering cholesterol concentrations and blood pressure).
- Physical exercise
The program of controlled exercises is struggling with factors that increase spacecraft. As a result, blood circulation and vascular functionality are improved. Exercises are also used to control weight in patients with obesity, hypertension and cholesterol.
Often, lifestyle modification is combined with drug therapy. For example:
- Statins help lower cholesterol.
- Antiplatelet agents such as aspirin help prevent clots.
- Various antihypertensive drugs are commonly used to control blood pressure.
If combined efforts to modify risk factors and drug therapy are insufficient to control the symptoms or combat the inevitable threat of ischemic manifestations, the doctor may resort to interventional or surgical procedures to eliminate vascular obstruction.
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