cholesterol /cho·les·ter·ol/ (kah-les´ter-ol) a eukaryotic sterol that in higher animals is the precursor of bile acids and steroid hormones and a key constituent of cell membranes. Most is synthesized by the liver and other tissues, but some is absorbed from dietary sources, with each kind transported in the plasma by specific lipoproteins. It can accumulate or deposit abnormally, as in some gallstones and in atheromas. Preparations are used as emulsfiers in pharmaceuticals. 
Cholesterol
cholesterol
cholesterol [ko-les´ter-ol]
)
Structure and metabolism of cholesterol.
HDL cholesterol , high-density–lipoprotein cholesterol (HDL-C) the serum cholesterol carried on high-density lipoproteins, approximately 20 to 30 per cent of the total.
LDL cholesterol , low-density–lipoprotein cholesterol (LDL-C) the serum cholesterol carried on low-density lipoproteins, approximately 60 to 70 per cent of the total.
cho·les·ter·ol (k -l s t-rôl , -r l)n. A white crystalline substance found in animal tissues and various foods, normally synthesized by the liver and important as a constituent of cell membranes and a precursor to steroid hormones. Its level in the bloodstream can influence the pathogenesis of certain conditions, such as the development of atherosclerotic plaque and coronary artery disease. |
Cholesterol
A fat-like substance that is made by the human body and eaten in animal products. Cholesterol is used to form cell membranes and process hormones and vitamin D. High cholesterol levels contribute to the development of atherosclerosis.
Mentioned in: Atherosclerosis, Cholesterol-Reducing Drugs, Hypolipoproteinemia, Lipoproteins Test, Rickets, Vitamin D Deficiency
cholesterol
[kəles′tərôl]
Etymology: Gk, chole + steros, solid
a waxy lipid soluble compound found only in animal tissues. A member of a group of compounds called sterols, it is an integral component of every cell in the body. It facilitates the absorption and transport of fatty acids. Cholesterol acts as the precursor for the synthesis of various steroid hormones, including cortisol, cortisone, and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone. It sometimes precipitates along with other compounds in the gallbladder to form gallstones. Cholesterol is found in foods of animal origin and is continuously synthesized in the body, primarily in the liver. Increased levels of low-density lipoprotein cholesterol may be associated with the pathogenesis of atherosclerosis, whereas higher levels of high-density lipoprotein cholesterol appear to lower the person's risk for heart disease. Normal adult levels of blood cholesterol are 150 to 200 mg/dL or 3.9 to 5.2 mmol/L (SI units). Also called cholesterin. See also high-density lipoprotein, low-density lipoprotein, sterol.
cholesterol [ko-les´ter-ol]
a steroid alcohol found in animal fats and oils, bile, blood, brain tissue, milk, egg yolk, myelin sheaths of nerve fibers, liver, kidneys, and adrenal glands. It is a precursor of bile acids and steroid hormones, and it occurs in the most common type of gallstone, in atheroma of the arteries, in various cysts, and in carcinomatous tissue. Most of the body's cholesterol is synthesized by the liver, but some is obtained in the diet from animal-derived foods. Plant-derived foods are cholesterol-free. Cholesterol is not transported free in the blood but is bound to certain proteins to form lipoproteins. Two important fractions of the serum lipoproteins are high-density lipoproteins (HDL) and low-density lipoproteins (LDL).
High levels of total serum cholesterol have been shown to be associated with a high risk for coronary artery disease and myocardial infarction. Research has drawn a distinction between HDL-C, the cholesterol carried on high-density lipoproteins and LDL-C, the cholesterol carried on low-density lipoproteins. The balance between HDL-C and LDL-C is more significant than the total concentration of cholesterol in the blood. The risk of coronary heart disease increases as LDL-C increases and HDL-C decreases.
Because HDL-C promotes the removal of excess cholesterol from the cells and its excretion from the body, it is thought to be beneficial rather than harmful. In contrast, LDL-C picks up cholesterol from ingested fats and from cells that synthesize it in the body and delivers it to blood vessels and muscles where it is deposited in the cells. The concentration of cholesterol in cells within the linings of the arteries contributes to the build-up of atherosclerotic plaques. (See also atherosclerosis.)
A third type of lipoprotein is known as very-low-density lipoprotein (VLDL). There is a preponderance of triglyceride and very little cholesterol in VLDL. Triglyceride is the basic type of lipid used for the storage of energy. The role of serum triglyceride in the formation of atherosclerotic plaques is not known. Those persons who are at high risk for heart disease, already have a heart condition, or are obese should limit the amount of fats and cholesterol in the foods they eat. LDL-C levels can be reduced by limiting dietary intake of saturated fat and cholesterol. Organ meats and egg yolks are high in cholesterol. HDL-C levels can be raised by exercise, stopping cigarette smoking, and losing excess body fat.
High levels of total serum cholesterol have been shown to be associated with a high risk for coronary artery disease and myocardial infarction. Research has drawn a distinction between HDL-C, the cholesterol carried on high-density lipoproteins and LDL-C, the cholesterol carried on low-density lipoproteins. The balance between HDL-C and LDL-C is more significant than the total concentration of cholesterol in the blood. The risk of coronary heart disease increases as LDL-C increases and HDL-C decreases.
Because HDL-C promotes the removal of excess cholesterol from the cells and its excretion from the body, it is thought to be beneficial rather than harmful. In contrast, LDL-C picks up cholesterol from ingested fats and from cells that synthesize it in the body and delivers it to blood vessels and muscles where it is deposited in the cells. The concentration of cholesterol in cells within the linings of the arteries contributes to the build-up of atherosclerotic plaques. (See also atherosclerosis.)
A third type of lipoprotein is known as very-low-density lipoprotein (VLDL). There is a preponderance of triglyceride and very little cholesterol in VLDL. Triglyceride is the basic type of lipid used for the storage of energy. The role of serum triglyceride in the formation of atherosclerotic plaques is not known. Those persons who are at high risk for heart disease, already have a heart condition, or are obese should limit the amount of fats and cholesterol in the foods they eat. LDL-C levels can be reduced by limiting dietary intake of saturated fat and cholesterol. Organ meats and egg yolks are high in cholesterol. HDL-C levels can be raised by exercise, stopping cigarette smoking, and losing excess body fat.
Structure and metabolism of cholesterol. From Dorland's, 2000.
Blood Cholesterol. Laboratory testing of cholesterol in the blood is often used as a preliminary test for a disorder of blood lipids. Although the normal values for total blood cholesterol vary according to age, diet, and nationality, levels above 200 mg/dl indicate a need for further testing and efforts to reduce the cholesterol level. In general, as the total cholesterol level rises above 150 mg/dl, the risk for coronary artery disease gradually increases. Persons with cholesterol levels above 260 mg/dl may require medication to lower their LDL-C levels and reduce the risk of heart disease.
Increased levels of cholesterol in the blood are found in cardiovascular disease and atherosclerosis, obstructive jaundice, hypothyroidism, nephrosis, and uncontrolled diabetes mellitus. Cholesterol exists in both a free and esterified form; the ratio of free to esterified cholesterol is significant in the diagnosis of certain diseases. For example, there is a markedly abnormal ratio of these two forms of cholesterol in hepatic biliary disease, infectious diseases, and extreme cholesterolemia.
Decreased levels of cholesterol in the blood are noted when there is malabsorption of cholesterol from the intestinal tract as in pernicious anemia, hemolytic jaundice, hyperthyroidism, and terminal cancer.
Increased levels of cholesterol in the blood are found in cardiovascular disease and atherosclerosis, obstructive jaundice, hypothyroidism, nephrosis, and uncontrolled diabetes mellitus. Cholesterol exists in both a free and esterified form; the ratio of free to esterified cholesterol is significant in the diagnosis of certain diseases. For example, there is a markedly abnormal ratio of these two forms of cholesterol in hepatic biliary disease, infectious diseases, and extreme cholesterolemia.
Decreased levels of cholesterol in the blood are noted when there is malabsorption of cholesterol from the intestinal tract as in pernicious anemia, hemolytic jaundice, hyperthyroidism, and terminal cancer.
cholesterol (k
·lesˑ·ter·
l),n organic compound produced in the liver and absorbed from food that is essential to the production of metabolic products and hormones.
)
Cholesterol.
cholesterol (k
les´trôl),n a lipid common to all animal, but not plant, cells. As a sterol, it contains the cyclopentanophenanthrene nucleus. High levels are found in nerve tissue, atheromas, gallstones, and cysts. Normally 140 to 220 mg are present in 100 ml of blood.
cholesterol
a steroid alcohol found in animal fats and oils, bile, blood, brain tissue, milk, egg yolk, myelin sheaths of nerve fibers, liver, kidneys and adrenal glands. It is a necessary component of all cell surface and intracellular membranes and a constituent of myelin in nervous tissue; it is a precursor of bile acids and steroid hormones, and it occurs in the most common type of gallstone, in atheroma of the arteries, in various cysts, and in carcinomatous tissue. Most of the body's cholesterol is synthesized, but some is obtained in the diet.
The preoccupation in human medicine with the relationship between cholesterol and the development of atheromatous plaques in the coronary arteries is not reflected in veterinary medicine. The importance of cholesterol to the veterinarian is limited to the measurement of blood cholesterol levels as an indicator of liver disease or thyroid activity.
cholesterol pneumonia
see endogenous-lipid pneumonia.
cholesterol
Biochemistry A precursor of steroid hormones and bile acids; it is an integral component of cell membranes and plasma lipoproteins, and found in animal fats, bile, blood, brain, milk, egg yolk, myelin sheaths, liver, kidneys, and
adrenal glands; it is absorbed from the diet and synthesized in the liver; diets high in saturated–animal fats ↑ cholesterol levels; it is the main component of the most common type of gallstones, and integral to arterial
atheromas, in cysts and in malignancy; it is a precursor of bile acids and important in the synthesis of steroid hormones; diets low in saturated fats ↓ cholesterol levels, as does exercise; ↑ cholesterol is associated with ASHD, CAD,
↑ risk of death due to acute MIs and strokes; total cholesterol–TC is measured in routine chemistry panels; cholesterol is transported in the circulation by carrier proteins, which are classified according to their
density–high-density lipoprotein—HDL, LDL, VLDL, based on density gradient ultracentrifugation; HDL-C is metabolized efficiently, and thus is 'good' cholesterol; 'bad cholesterol,' LDL-C, is inefficently
metabolized High risk for ASHD TC > 6.21 mmol/L–US > 240 mg/dL; LDL-C > 160 mg/dl, HDL-C
< 35 mg/dl Borderline risk 5.17-6.18 mmol/L–US: 200-239 mg/dL Low risk < 5.17 mmol/L–US 200 mg/dL, LDL-Cl < 130 mg/dL, HDL-C > 55 mg/dL ↑ in Hypercholesterolemia, nephrotic syndrome, hypothyroidism, biliary cirrhosis ↓ in Malnutrition, hyperthyroidism, colorectal CA Management, ↑ cholesterol Diet–↓ saturated fats, weight loss, regular exercise, medications. See Bad cholesterol, Fish, Good cholesterol, HDL, Hypercholesterolemia, LDL, RLP, VLDL.
< 35 mg/dl Borderline risk 5.17-6.18 mmol/L–US: 200-239 mg/dL Low risk < 5.17 mmol/L–US 200 mg/dL, LDL-Cl < 130 mg/dL, HDL-C > 55 mg/dL ↑ in Hypercholesterolemia, nephrotic syndrome, hypothyroidism, biliary cirrhosis ↓ in Malnutrition, hyperthyroidism, colorectal CA Management, ↑ cholesterol Diet–↓ saturated fats, weight loss, regular exercise, medications. See Bad cholesterol, Fish, Good cholesterol, HDL, Hypercholesterolemia, LDL, RLP, VLDL.
Patient discussion about cholesterol.
Q. How can I increase my HDL cholesterol levels? My Doctor told me that my cholesterol levels are not good and that I should lower my LDL and higher my HDL. I understand how to lower the cholesterol, but how can I increase the HDL?
A. Here are a few things you can do in order to raise your HDL levels:
Aerobic exercise
Lose weight
Stop smoking
Cut out the trans fatty acids from your diet.
Alcohol: one or two drinks per day can significantly increase HDL levels
Increase the monounsaturated fats in your diet.
Add soluble fiber to your diet.
Aerobic exercise
Lose weight
Stop smoking
Cut out the trans fatty acids from your diet.
Alcohol: one or two drinks per day can significantly increase HDL levels
Increase the monounsaturated fats in your diet.
Add soluble fiber to your diet.
Q. Can omega-3 make my cholesterol lower? My doctor told me that I have too much cholesterol in my blood, and that it can cause heart attack or stroke, but if I keep it low than my risk will be lower. He told me that because it’s not that high level I can try to change my diet before I have to start taking medication. I heard that omega-3 can make my cholesterol level low. Is that true? Do I have to take it in pills? Is it safe?
A. You can consume omega-3 either as pills or in fish oil, fatty fish (such as salmon) and vegetarian food such as flaxseed and flaxseed oil, canola oil, soybean oil, and nuts.
Q. What is a cholecystectomy and how is it done? My Doctor diagnosed me with gallstones and said I have to have a cholecystectomy surgery. What is this and how is it done?
A. Cholecystectomy is a surgery in which the gallbladder is removed. Don't be alarmed since you can live without your gallbladder. When the gallbladder is gone, bile flows directly from the liver into the small intestine.
You will probably have a laparoscopic cholecystectomy, which means a surgeon will make a small slit in your abdomen, then insert a tubelike instrument which has a camera and surgical instruments attached. This is used to take out the gallbladder with the stones inside it.
This procedure causes less pain than open surgery, is less likely to cause complications, and has a faster recovery time. This surgery is performed in an operating room and you will be under general anesthesia. It usually takes 20 minutes to one hour.
Read more or ask a question about cholesterolYou will probably have a laparoscopic cholecystectomy, which means a surgeon will make a small slit in your abdomen, then insert a tubelike instrument which has a camera and surgical instruments attached. This is used to take out the gallbladder with the stones inside it.
This procedure causes less pain than open surgery, is less likely to cause complications, and has a faster recovery time. This surgery is performed in an operating room and you will be under general anesthesia. It usually takes 20 minutes to one hour.
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