Definition of the disease. Causes of the disease
High cholesterol is a disorder in the composition of fats in the blood, accompanied by an increase in its cholesterol concentration. It is a subset of lipid disorders, as an increase in blood cholesterol levels is only a symptom and not a separate disease in itself. Therefore, the doctor needs to determine the relationship between high cholesterol in each specific case, although this is not always possible, and in most cases, moderate elevation in blood cholesterol levels is due to the characteristics of the modern Western lifestyle.
Fats – are biological substances insoluble in water and soluble in organic solvents due to their composition properties. Fats are the most common (but not the only) representatives of lipids. Fats also include cholesterol and its esters, phospholipids, waxes, and some other substances.
What is fat metabolism?
These are processes related to the absorption of fats from food and their absorption in the digestive system, transport in the blood, entry into cells, and all the chemical transformations accompanying these substances, in addition to their excretion and the excretion of their chemical transformation products from the body. All these processes fall under the concept of “metabolism,” and any disorder in any of these numerous stages is a disorder in fat metabolism, and disorders in cholesterol metabolism are one of these disorders, but they are probably the most common.
There are two main causes of high cholesterol – poor diet and genetic predisposition/genetic abnormalities. In addition, some diseases (such as diabetes, hyperthyroidism, and chronic glomerulonephritis) are associated with an increase in blood cholesterol concentration. Taking certain medications (such as steroids, hormonal contraceptives, and beta-adrenergic blockers) can also lead to high cholesterol levels.
It has been proven that dietary habits that have become common among most people within the framework of what is known as the Western lifestyle over the past century lead to disorders in cholesterol metabolism, especially when these factors increase with decreased physical activity and smoking. These include excessive intake of calories, high fat content in meat, fatty dairy products, processed foods, pastries, fat, palm oil, sweets, and sweet products, and conversely, decreased consumption of vegetables, fruits, legumes, and whole grains.
Symptoms of High Cholesterol
The tricky aspect of high cholesterol is that it may not show for many years, and a person can feel completely healthy. Disorders can only be detected through changes in chemical indicators in the blood – often such indicators as total cholesterol, low-density lipoprotein cholesterol (“bad cholesterol”), high-density lipoprotein cholesterol, and triglycerides are determined. Some of the potential signs of high cholesterol can include:
- Accumulation of fatty plaques in the blood vessels.
- Appearance of yellowish deposits on the eyelids known as “xanthelasma.”
- Appearance of yellowish or orange deposits on the skin or tendons, often on the Achilles tendons, leading to tendon enlargement.
- Presence of a fatty ring around the cornea, which is diagnostically significant only for individuals under 45 years old and appears as a white arc or halo around the iris of the eye.
Note: Absence of yellowish nodules and xanthelasma does not necessarily mean absence of the disease or that cholesterol levels are normal.
Classification and Stages of Cholesterol Elevation
Classifications of lipid metabolism disorders are often not helpful to the patient, as they largely depend on changes in blood lipid indicators. In the initial division, all lipid disorders can be divided into:
- High cholesterol – elevated levels of total cholesterol and low-density lipoprotein cholesterol (“bad cholesterol”).
- High triglycerides – increased concentration of triglycerides (fats) in the blood, which are not present alone but mostly in the form of low-density lipoproteins. Elevated cholesterol increases the risk of developing artery-related diseases. If high-density lipoprotein cholesterol (“good cholesterol”) is low – less than 1.0 mmol/L for men and less than 1.2 mmol/L for women – this is also undesirable because it accelerates the development of artery hardening. Significant elevation in triglycerides can lead to acute pancreatitis (inflammation and destruction of the pancreas), while moderate elevation in triglycerides accelerates the development of artery hardening.
Complications of High Cholesterol
If high levels of cholesterol in the blood persist for a long period (years), especially if there are other unfavorable factors present simultaneously, such as high blood pressure, smoking, and diabetes, fatty deposits may accumulate in the arteries, narrowing or sometimes completely blocking their passage. The accumulation may be small, but if broken, its contents coming into contact with the blood can quickly form a clot, and may completely block the vessel’s passage within minutes. In this case, it can cause a heart attack (if one of the vessels supplying the heart is blocked) or a stroke (if one of the vessels supplying the brain is affected). Usually, this rule holds true: the higher the cholesterol level in the blood (especially if there is a sub-elevation in low-density lipoprotein cholesterol), the greater the risk of affecting the internal arteries with platelet accumulation, the greater the risk of heart attack or stroke, and the greater the risk of developing diseases related to narrowed blood flow in this or that organ, such as:
- Angina pectoris – manifests with pain/discomfort in the chest during physical activity (walking or running).
- Peripheral arterial disease of the lower extremities – manifests with pain/burning or rapid fatigue in leg muscles during walking.
Diagnosing High Cholesterol
A comprehensive evaluation of changes in biochemical indicators in the blood that distinguish fat metabolism disorders is key to diagnosing lipid disorders and cholesterol metabolism as a specific condition of lipid disorders. Typically, four indicators are assessed:
- Total cholesterol.
- Low-density lipoprotein cholesterol (LDL-C).
- High-density lipoprotein cholesterol (HDL-C).
- Triglycerides.
Under “total cholesterol” here, it refers to the sum of its concentration, while cholesterol in the blood is distributed among different fractions – in low-density lipoproteins, high-density lipoproteins, and some other types.
In a simplified manner, doctors often refer to cholesterol found in low-density lipoproteins as “bad,” while that found in high-density lipoproteins as “good.” This simplified childhood description stems from the fact that low-density lipoprotein concentration in the blood is associated with the development of artery hardening (appearance and increase of fatty plaques in blood vessels), while high-density lipoproteins act in the opposite direction. Direct concentrations of these lipoproteins in the biochemical laboratory cannot be determined, so cholesterol concentrations in each branch of lipoproteins are estimated.
As part of routine screening for adults, the total cholesterol concentration in the blood is determined for everyone. If it is elevated (more than 5 mmol/L for individuals without cardiovascular diseases), it is logical to measure concentrations of “bad” and “good” cholesterol, in addition to triglycerides. By obtaining this comprehensive picture of lipid profile in the blood, the type of lipid metabolism disorder in the individual can usually be determined with a high degree of probability. The treatment recommended by the doctor will largely depend on that.
However, a good doctor diagnoses and treats the whole person, not just the biochemical results. Therefore, the main thing the doctor must assess in a patient with lipid metabolism disorders is the risk of adverse cardiovascular events, such as heart attacks, strokes, death from heart and vascular causes, development of angina pectoris, as well as increased risk of acute pancreatitis, which sharply increases when triglyceride concentration exceeds 10 mmol/L. Therefore, the doctor takes into account the major risk factors for developing artery hardening: age, smoking, high blood pressure, diabetes, and others. Special scales and calculators may be used to calculate the risk of occurrence.
The doctor examines the patient, paying attention to the skin and tendons (where there may be fatty deposits with elevated concentration in the blood), and the condition of the cornea in the eye (where a specific arc may appear on the corneal edge due to fat deposits there). Sometimes, a search is made for fatty plaques in blood vessels, which can be easily accessed for non-invasive investigation (not associated with violating the integrity of the skin and mucous membranes), such as the carotid arteries, which are examined using ultrasound. If there is a reason to suspect artery hardening in other blood vessels (such as the heart, brain, lower extremities, and kidneys) based on the analysis of the entire clinical picture, appropriate tests are performed to confirm the presence of this condition.
Treatment of hypercholesterolemia
Treatment for high cholesterol aims primarily to prevent serious complications or at least reduce their risks. This is achieved by achieving an intermediary goal, which is correcting the cholesterol level in the blood, as well as by influencing other known factors associated with the risks of atherosclerosis.
When a balance in the cholesterol level in the blood is achieved and maintained within an ideal range for a long period, there is a gradual reduction in the risk of conditions like angina, stroke, and death due to heart and vascular causes. Therefore, it is crucial to maintain cholesterol levels in the blood (especially LDL cholesterol) within the optimal range for as long as possible, preferably lifelong.
In many cases, lifestyle changes alone are not enough to achieve this, especially with the numerous temptations individuals face. In cases of high risk of cardiovascular complications, low cholesterol treatments should be pursued regardless of the patient’s willingness to improve their lifestyle.
Currently, the concept of a “normal cholesterol level” has been abandoned in cardiology. Instead, the term “optimal cholesterol level” is used, which depends on the total risk of cardiovascular diseases. Based on available information about the patient, the doctor calculates these risks:
- For very high risk (including all patients already suffering from ischemic heart disease or stroke, those with diabetes, and certain other categories), the optimal level for LDL cholesterol is less than 1.8 mmol/L.
- For high risk (if the patient does not yet have atherosclerotic heart or vascular disease, but has several risk factors, such as a 50-year-old male smoker with high blood pressure and a cholesterol level of 6 mmol/L), the optimal level for LDL cholesterol would be less than 2.6 mmol/L.
- For all others without high or serious cardiovascular risks, the optimal level for LDL cholesterol should be less than 3.0 mmol/L.
If there is a genetic predisposition behind high cholesterol, lifestyle changes (such as diet, physical activity, and quitting smoking) can only somewhat improve the blood chemistry composition. Therefore, most of the time, additional drug therapy is necessary.
Lifestyle changes that can help reduce cholesterol levels and decrease the risk of cardiovascular diseases include:
- Reducing intake of saturated fats, such as fatty meats, fatty dairy products, sweets, and sugary foods.
- Quitting smoking completely.
- Losing weight by at least 10% of the original weight if overweight or obese.
- Increasing regular physical activity, such as running, cycling, sports, swimming, etc., for at least 4-5 times a week for 30-40 minutes each session.
All these mentioned measures to change the blood lipid composition lead to improvements and significantly reduce the risk of cardiovascular diseases associated with atherosclerosis (such as heart attack, stroke, ischemic heart diseases, etc.).
Drug therapy for lowering cholesterol levels and reducing the risk of cardiovascular diseases depends on the individual’s health condition and specific needs. However, here is a general arrangement that may be helpful:
- Statins: These are the first-line drugs usually used to lower cholesterol levels. They include atorvastatin (Lipitor), rosuvastatin (Crestor), simvastatin (Zocor), pravastatin (Pravachol), and others.
- Ezetimibe: Used as an additional treatment to statins in some cases for further cholesterol reduction.
- PCSK9 inhibitors (Alirocumab and Evolocumab): Used in cases where statins or ezetimibe are not effective, or in cases of familial hypercholesterolemia.
- Bile acid sequestrants (e.g., Colesevelam): Can be used in some cases as an option to lower cholesterol in individuals who cannot tolerate statins or PCSK9 inhibitors.
General precautions: Drug therapy should be prescribed according to a comprehensive evaluation of the patient, including medical history and specific factors.