Cholesterol

Our body produces a fat-like waxy substance known as cholesterol. It is found in the bloodstream of the body and helps to make various hormones, vitamin D, and several other substances that help in the digestion of food such as bile.

Although the presence of cholesterol is important for the body to function properly excess of cholesterol can impart disastrous consequences on the health status.

When cholesterol continues to accumulate, it narrows the blood vessel causing poor blood flow to the heart ultimately causing the heart attack. High cholesterol is inheritable but lifestyle and food also contribute to the elevation of cholesterol level.

Good and bad cholesterol

High-density lipoprotein (HDL) is considered good cholesterol. HDL helps to remove excess cholesterol from cells, tissues, and plaque in blood vessels this is why HDL is called the good cholesterol. Moreover, it takes cholesterol back to the liver.

Low-density lipoprotein or LDL Is considered as bad cholesterol. LDL travels in the bloodstream and transports cholesterol to the relevant cells. Sometimes, your body forms plaque which is a type of fatty deposit that is formed by having a lot of LDL in the body. With the passage of time, this phenomenon reduces your blood flow and that’s why it is considered to be bad cholesterol for your body.

Different perspective studies have shown that there is a reverse relationship between the chances of coronary heart disease and HDL. (1)

Furthermore, every 1 mg/dL increase in HDL decrease the risk of CHD by 2% in men and 3% in the woman. (2)

Symptoms

There are usually no signs or symptoms of high blood cholesterol but it can be detected with a blood test. One is likely to have high cholesterol if any member of the family has it. Following symptoms are observed in familial hypercholesterolemia

  • Tendon xanthomas
  • Xanthelasma
  • Corneal arcus
  • Premature atherosclerosis
  • Angina
  • Aortic stenosis

Causes.

A diet high in bad cholesterol or LDL can increase cholesterol levels and lead to heart disease. There are genetic factors as well as acquired causes of hypercholesterolemia. Genetic mutations in the LDL receptor gene increases LDL-C in blood. This defect accounts for about 85% of familial hypercholesterolemia.

Being overweight is a major part of having high cholesterol. Many people, struggling with obesity, consume too much LDL or bad cholesterol.

Smoking lowers HDL and increases LDL causing Hypercholesterolemia.

Older people are at greater risk of getting high cholesterol that’s because most of them have minimal physical activity. Women and men over 45 are automatically at a greater risk of getting high cholesterol.

Another cause of hypercholesterolemia is uncontrolled diabetes. In insulin deficiency, chylomicrons and VLDL breakdown lipoprotein lipase, and it increases LDL in the bloodstream. (3)

Complications.

If plaque builds up in the artery it can lead to

Arteriosclerosis.  It refers to the coagulation of fats and cholesterol inside the artery walls which restricts the blood flow.

Coronary heart disease. Fatty deposits completely block the blood flow. As a result, the heart does not get enough of the oxygen rich blood, which then leads to coronary heart disease.

Angina.

When the heart gets less amount of blood and oxygen due to hypercholesterolemia then a person feels pain and pressure in the chest which is known as angina.

Heart attack.

Sometimes fatty deposits rupture in the artery leading to the heart and cause blood to clot at the side of injury this causes a heart attack.

Stroke.

If atherosclerosis occurs in the artery leading to the brain then decrease blood flow and oxygen towards the brain can cause a stroke.

Diagnosis

Usually, hypercholesterolemia does not show any signs and symptoms and a person needs to have a lipid profile or lipid panel.

Lipid profile or lipid panel typically reports.

  • LDL cholesterol
  • HDL cholesterol
  • total cholesterol
  • Triglycerides

For accurate results, a patient must not eat or drink anything for 9 to 12 hours before giving the blood sample.

Interpretation of results

LDL cholesterol below 70 mg/dL is considered good for the patient who is diabetic and has heart disease. LDL cholesterol less than 129 mg/dL is considered optimal for a normal person but it is high for a heart patient. If the value is more than 129 mg/dL then it is high for both normal as well as a heart patient.

HDL cholesterol level above 60 mg/dL is considered best for both men and women. if it is below 50 mg/dL and 40 mg/dL then it is poor for women and men respectively.

Total cholesterol level below 200 mg/dL is considered desirable and above 250 mg/dL is interpreted as very high.

Treatment

Treatment of familial hypercholesterolemia mainly aims to reduce LDL levels to decrease the risk of cardiovascular disease. lifestyle modifications help in lowering LDL. These include quitting smoking, alcohol, and lowering the number of saturated fats in the diet like those found in dairy and fast food.

Along with lifestyle modifications treatment with pharmacological agents is also important to reduce LDL.

  1. Statins lower the LDL by inhibiting a substance, a liver need to make cholesterol. It also aids the body to reabsorb cholesterol from arterial fatty deposits and potentially decreases the risk of Coronary artery disease.

Statins include fluvastatin, atorvastatin, lovastatin, simvastatin, and rosuvastatin.

  1. The small intestine absorbs the cholesterol from the food and delivers it to the bloodstream. Ezetimibe reduces this absorption of cholesterol from the intestine.
  2. Colestipol, cholestyramine, and colesevelam binds to the bile acids. It prompts the liver to utilize more cholesterol to make more bile acids. This lowers cholesterol concentration in the bloodstream.
  3. Fibrates like fibrates also reduce cholesterol by reducing the liver activity of producing very-low-density lipoprotein VLDL and cholesterol.
  4. Niacin also functions the same as fibrates. by limiting the liver’s function of producing cholesterol.
  5. Another class of drugs named PCSK9 inhibitors is also introduced. It is given intravenously. It aids the liver to absorb LDL cholesterol thus lowering their amount in the bloodstream. The combination therapy of PCSK9 and statins causes more than 60% reduction in LDL.

References

  1. http://dx.doi.org/10.1056/NEJMoa064278
  2. https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/symptoms-causes/syc-20350800
  3. https://www.heart.org/en/health-topics/cholesterol/about-cholesterol