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What cholesterol is and what blood tests for cholesterol show

Discussion in 'JF Doctor' started by MziziMkavu, Jul 21, 2010.

  1. MziziMkavu

    MziziMkavu JF-Expert Member

    Jul 21, 2010
    Joined: Feb 3, 2009
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    [FONT=&quot]About high cholesterol [/FONT]

    [FONT=&quot]About two in three adults have a cholesterol level that is higher than recommended. Having high cholesterol affects your heart and blood vessels and increases your risk of developing cardiovascular disease (CVD). High cholesterol causes fatty deposits (known as plaques) to build up inside your blood vessels.[/FONT]
    [FONT=&quot]In time, the blood vessels supplying your heart may become so narrow that they can't deliver enough oxygen to the heart muscle, particularly when you're exerting yourself. This can cause you to feel chest pain (angina). If a fatty plaque breaks off, it may cause a blood clot which can block blood flow to your heart (heart attack) or brain (stroke).[/FONT]
    [FONT=&quot]What are the functions of cholesterol? [/FONT]

    · It builds and maintains cell membranes (outer layer), it prevents crystallization of hydrocarbons in the membrane
    · It is essential for determining which molecules can pass into the cell and which cannot (cell membrane permeability)
    · It is involved in the production of sex hormones (androgens and estrogens)
    · It is essential for the production of hormones released by the adrenal glands (cortisol, corticosterone, aldosterone, and others)
    · It aids in the production of bile
    · It converts sunshine to vitamin D

    · It is important for the metabolism of fat soluble vitamins, including vitamins A, D, E, and K
    · It insulates nerve fibers
    [FONT=&quot]Types of cholesterol [/FONT]

    [FONT=&quot]Cholesterol is transported around your body attached to a protein in your blood. This combination of fat and protein is called a lipoprotein. There are different types of lipoprotein, depending on how much fat there is in relation to protein. [/FONT]
    [FONT=&quot]HDL (high-density lipoprotein)[/FONT]

    [FONT=&quot]A small amount of cholesterol is transported as HDL, which is mostly protein and not much fat. The role of HDL is to transport excess cholesterol from the tissues (including the walls of arteries) to the liver for disposal. As HDL helps prevent cholesterol building up in your blood vessels, you have a decreased risk of heart disease if you have high levels of this type. HDL is considered to be the "good" type of cholesterol. Women tend to have higher HDL levels than men. HDL can be increased by physical exercise.[/FONT]
    [FONT=&quot]LDL (low-density lipoprotein) [/FONT]

    [FONT=&quot]Most of your body's cholesterol (around 70 percent) is transported in this form. It consists mainly of fat, with not much protein. LDLs are chiefly involved in transporting cholesterol from the liver to the cells. High levels of LDL are associated with an increased risk of CVD as LDL causes cholesterol to be deposited in your blood vessels. LDL is considered to be the "bad" type of cholesterol.[/FONT]
    [FONT=&quot]VLDL (very low-density lipoprotein) and chylomicrons[/FONT]

    [FONT=&quot]These lipoproteins account for a small percentage of your body's cholesterol, but they are rich in triglycerides and transport them to the tissues. [/FONT]
    [FONT=&quot]Triglycerides [/FONT]

    [FONT=&quot]Triglycerides are a different type of fat, mostly coming from fats in your food. Energy from food that is eaten and not used immediately is converted into triglycerides and transported to fat cells for storage. This provides you with an important source of stored energy.[/FONT]
    [FONT=&quot]Although most triglycerides are stored as fat, low levels are also found in your blood. A raised level of blood triglycerides together with high LDL can increase your risk of heart disease, particularly if you have diabetes.[/FONT]
    [FONT=&quot]Total cholesterol (TC)[/FONT]

    [FONT=&quot]Having a high TC level is a risk factor for future health problems. However, it's important to consider the relative amounts of HDL and LDL. This is often referred to as the TC:HDL ratio. You should aim for a high level of HDL and a low level of LDL (a low TC:HDL ratio). [/FONT]

    Cholesterol is carried in the blood by molecules called lipoproteins. A lipoprotein is any complex or compound containing both lipid (fat) and protein. The three main types are:
    · LDL (low density lipoprotein) - people often refer to it as bad cholesterol. LDL carries cholesterol from the liver to cells. If too much is carried, too much for the cells to use, there can be a harmful buildup of LDL. This lipoprotein can increase the risk of arterial disease if levels rise too high. Most human blood contains approximately 70% LDL - this may vary, depending on the person.
    · HDL (high density lipoprotein) - people often refer to it as good cholesterol. Experts say HDL prevents arterial disease. HDL does the opposite of LDL - HDL takes the cholesterol away from the cells and back to the liver. In the liver it is either broken down or expelled from the body as waste.
    · Triglycerides - these are the chemical forms in which most fat exists in the body, as well as in food. They are present in blood plasma. Triglycerides, in association with cholesterol, form the plasma lipids (blood fat). Triglycerides in plasma originate either from fats in our food, or are made in the body from other energy sources, such as carbohydrates
    . Calories we consume but are not used immediately by our tissues are converted into triglycerides and stored in fat cells. When your body needs energy and there is no food as an energy source, triglycerides will be released from fat cells and used as energy - hormones control this process.

    [FONT=&quot]Symptoms of high cholesterol[/FONT]

    [FONT=&quot]A high cholesterol level may only be revealed if you develop symptoms of heart disease. Sometimes, yellow patches (known as xanthomas) may develop around your eyes or elsewhere on your skin - these are cholesterol deposits and indicate that you have high cholesterol levels in your blood.[/FONT]
    [FONT=&quot]Symptoms of high cholesterol (hypercholesterolaemia) [/FONT]

    Symptoms of high cholesterol do not exist alone in a way a patient or doctor can identify by touch or sight. Symptoms of high cholesterol are revealed if you have the symptoms of atherosclerosis, a common consequence of having high cholesterol levels. These can include:
    · Narrowed coronary arteries in the heart (angina)
    · Leg pain when exercising - this is because the arteries that supply the legs have narrowed.
    · Blood clots and ruptured blood vessels - these can cause a stroke
    or TIA (mini-stroke

    · Ruptured plaques - this can lead to coronary thrombosis (a clot forming in one of the arteries that delivers blood to the heart). If this causes significant damage to heart muscle it could cause heart failure

    · Xanthomas - thick yellow patches on the skin, especially around the eyes. They are, in fact, deposits of cholesterol. This is commonly seen among people who have inherited high cholesterol susceptibility (familial or inherited hypercholesterolaemia).
    [FONT=&quot]Complications of high cholesterol[/FONT]

    [FONT=&quot]There is an increased risk of heart disease, arterial disease and strokes. Your GP will discuss possible complications of high cholesterol with you. [/FONT]
    [FONT=&quot]Dangers of high cholesterol levels[/FONT]

    High cholesterol levels can cause:
    · Atherosclerosis - narrowing of the arteries.
    · Higher coronary heart disease risk - an abnormality of the arteries that supply blood and oxygen to the heart.
    · Heart attack - occurs when the supply of blood and oxygen to an area of heart muscle is blocked, usually by a clot in a coronary artery. This causes your heart muscle to die.
    · Angina - chest pain or discomfort that occurs when your heart muscle does not get enough blood.
    · Other cardiovascular conditions - diseases of the heart and blood vessels.
    · Stroke and mini-stroke - occurs when a blood clot blocks an artery or vein, interrupting the flow to an area of the brain. Can also occur when a blood vessel breaks. Brain cells begin to die.
    [FONT=&quot]If both blood cholesterol and triglyceride levels are high, the risk of developing coronary heart disease
    rises significantly.[/FONT]

    [FONT=&quot]Causes of high cholesterol[/FONT]

    [FONT=&quot]There are several factors that may contribute to you having high blood cholesterol. These include: [/FONT]

    • a diet high in saturated fat and cholesterol
    • a lack of exercise - this can increase your LDL levels and decrease your HDL levels
    • family history - you're more likely to have high cholesterol if you have a close male relative aged under 55 or a female relative aged under 65 affected by heart disease
    • being overweight
    • age and gender - your cholesterol levels generally rise with increasing age, and men are more likely to be affected than women
    • drinking more than the recommended daily amount of alcohol
    Lifestyle causes

    • Nutrition - although some foods contain cholesterol, such as eggs, kidneys, eggs and some seafoods, dietary cholesterol does not have much of an impact in human blood cholesterol levels. However, saturated fats do! Foods high in saturated fats include red meat, some pies, sausages, hard cheese, lard, pastry, cakes, most biscuits, and cream (there are many more).
    • Sedentary lifestyle - people who do not exercise and spend most of their time sitting/lying down have significantly higher levels of LDL (bad cholesterol) and lower levels of HDL (good cholesterol).
    • Bodyweight - people who are overweight/obese are much more likely to have higher LDL levels and lower HDL levels, compared to people who are of normal weight.
    • Smoking - this can have quite a considerable effect on LDL levels.
    • Alcohol - people who consume too much alcohol regularly, generally have much higher levels of LDL and much lower levels of HDL, compared to people who abstain or those who drink in moderation
    [FONT=&quot]Rarely, high cholesterol can be caused by a condition which may run in your family - this is called 'familial hypercholesterolaemia'. About one in 500 people have this condition. [/FONT]
    [FONT=&quot]Other conditions such as poorly controlled diabetes, certain kidney and liver diseases, and an underactive thyroid may also cause high cholesterol. Some medicines such as beta-blockers, steroids or thiazides (a type of diuretic) may also affect blood lipid levels. [/FONT]
    [FONT=&quot]Diagnosis of high cholesterol[/FONT]

    [FONT=&quot]Measuring cholesterol involves a blood test. Usually you will be asked not to eat for 12 hours before the test so that your food is completely digested and doesn't affect the test. A blood sample may be taken either by a needle and a syringe, or by a finger prick. You can have this test done at your GP surgery, at hospital, or as part of a health assessment examination.[/FONT]
    [FONT=&quot]Home-testing kits for cholesterol are also available but may not be very accurate. Speak to your pharmacist about your result if you choose to use a kit.[/FONT]
    [FONT=&quot]The amount of cholesterol in your blood is measured in units called millimoles per litre of blood, usually shortened to 'mmol/litre', 'mmol/L' or 'mM'. Current UK guidelines state that it's desirable to have a total cholesterol level under 5mmol/L, and an LDL level under 3mmol/L. However, you should aim to have a total cholesterol level under 4mmol/L and an LDL level under 2mmol/L if you're at high risk of heart disease. [/FONT]
    [FONT=&quot]Who should have a cholesterol test?[/FONT]

    [FONT=&quot]You should have your cholesterol levels regularly checked by your GP if you have CVD (or are at high risk of CVD) or if you have a family history of high cholesterol.[/FONT]
    [FONT=&quot]Treatment of high cholesterol[/FONT]

    [FONT=&quot]There are two ways to help lower high cholesterol. The first is with lifestyle changes including changing your diet, managing your weight and increasing exercise. The second is to combine lifestyle changes with cholesterol-lowering medicines.[/FONT]
    [FONT=&quot]Self-help [/FONT]

    [FONT=&quot]Healthy eating can reduce cholesterol. Your diet should be low in saturated fats in particular, and low in fat overall. Biscuits, cakes, pastries, red meat, hard cheese and butter all tend to be high in saturated fats, so cut down on these foods. [/FONT]
    [FONT=&quot]Some foods contain cholesterol. These foods include eggs, prawns and offal such as liver and kidneys. This type of cholesterol is known as dietary cholesterol and it has a much lower effect on blood cholesterol than saturated fat in your diet. You don't need to cut down on these foods unless your doctor has advised you to. [/FONT]
    [FONT=&quot]It's also important to eat plenty of fibre, especially soluble fibre, which is thought to lower cholesterol. Soluble fibre is found in fruits and vegetables, beans and oats. Aim to eat at least five portions of fruit and vegetables each day. Foods containing substances called plant sterols or stanols may help to lower cholesterol.[/FONT]
    [FONT=&quot]If you're overweight, an excess weight loss plan may help you to reduce your LDL levels and increase your HDL levels. Increasing your physical activity may enhance the cholesterol-lowering effects of diet.[/FONT]
    [FONT=&quot]As high cholesterol can increase your risk of heart disease, you should reduce any additional risk of developing heart disease, eg by stopping smoking.[/FONT]
    [FONT=&quot]Medicines [/FONT]

    [FONT=&quot]Your GP may prescribe cholesterol-lowering medicines if you already have heart disease, or are at high risk of getting it because you have other risk factors. The aim of treatment is to reduce your total cholesterol levels by a quarter or to less than 4mmol/L. [/FONT]
    [FONT=&quot]The main group of medicines for lowering cholesterol are the statins. Available statins include atorvastatin (Lipitor), fluvastatin (Lescol), pravastatin (Lipostat), rosuvastatin (Crestor) and simvastatin (Zocor). They work by reducing the production of cholesterol in the liver. These medicines can have side-effects such as indigestion and muscle pains. [/FONT]
    [FONT=&quot]Other types of medicines to reduce cholesterol include fibrates, nicotinic acid and cholesterol-absorption inhibitors such as ezetimibe (Ezetrol), but these are generally less effective than statins or have more side-effects. Your GP can tell you more about these medicines and suggest the most suitable treatment for you.[/FONT]
    [FONT=&quot]Prevention of high cholesterol[/FONT]

    [FONT=&quot]You may be able to prevent the development of high cholesterol by maintaining a healthy weight, eating a healthy diet, stopping smoking, not drinking excessive amounts of alcohol and taking regular exercise. However, if your family has a history of high cholesterol, it may be difficult to prevent yourself from having it too.[/FONT]