Lipid Profile Flashcards
What is the Total cholesterol test used for and what are the normal values?
Cholesterol testing used to determine risk for coronary artery disease and for evaluation of hyperlipidemias
Normal < 200 mg/dL
Cholesterol can vary day to day by 15% and may show an 8% difference within the same day
Total cholesterol is not a good preditor of heart disease by itself. What else is looked at to determine risk?
Total cholesterol done as part of a lipid profile as well as looking at other risk factors:
Gender, age, blood pressure, diabetes, smoker, etc.
What is the main lipid associated with arteriosclerotic vascular disease?
LDL
Where does most cholesterol come from and what is produced from it?
Most comes from foods of animal origin and is metabolized by the liver to its free form and is then transported by lipoproteins.
Required for production of steroids, sex hormones, bile acids, and cellular membranes
Cholesterol is bound to LDL and HDL. What % of cholesterol is bound to each one?
75% is bound to low density lipoproteins (LDL)
25% is bound to high density lipoproteins (HDL).
Which lipoprotein is most directly associated with increased risk for CAD?
LDL
This algorithm determines the risk for an ischemic event over the course of the next decade.
Framingham Coronary Prediction algorithm
This algorithm takes into account:
AGE, Total Cholesterol, HDL cholesterol, Blood pressure, diabetes, smoker
Total cholesterol interfering factors
Pregnancy associated with elevation
Oophorectomy and postmenopausal states associated with elevation
Recumbent position associated with decreased levels
Drugs that cause increased levels include anabolic steroids, beta blockers, corticosteroids, oral contraceptives, thiazide diuretics
Drugs that cause decreased levels include androgens, captopril, clofibrate, colestipol, niacin, and statins
Causes of Increased Total cholesterol
Familial hypercholesterolemia and familial hyperlipidemia – enzymatic deficiencies in lipid metabolism
Hypothyroidism, uncontrolled diabetes mellitus, nephrotic syndrome, pregnancy, high cholesterol diet, hypertension, MI, atherosclerosis, biliary cirrhosis, stress
Causes of decreased level of Total Cholesterol
Malabsorption, malnutrition, and advanced cancer – dietary intake is decreased so fat levels and cholesterol levels fall
Hyperthyroidism, cholesterol lowering medications, pernicious anemia, hemolytic anemia, sepsis, liver disease, and MI
What are the four types of lipoproteins?
HDL
LDL
VLDL
Chylomicrons
What are lipoproteins predictors of and what are the normal ranges?
Accurate predictor of heart disease. Performed to identify people at risk for developing heart disease and to monitor therapy if abnormalities are found.
Normal findings
HDL: Male: > 45 mg/dL, Female: > 55 mg/dL
LDL: < 130 mg/dL
VLDL: 7-32 mg/dL
What is the function of Lipoproteins in the body?
Lipoproteins are proteins in the blood that transport cholesterol, triglycerides, and other insoluble fats. They are markers indicating levels of lipids in the bloodstream and are classified by their measured density.
What is the order of lipoproteins from largest and least dense(more fat) to smaller and most dense(more protein)
Chylomicron
VLDL
LDL
HDL
What is the function of chylomicrons?
carry triacylglycerol (fat) from intestines to liver, skeletal muscle, and adipose tissue
What is the function of VLDL’s?
carry newly synthesized triacylglycerol from liver to adipose tissue
What is the function of LDL’s?
carry cholesterol from liver to cells of the body – “bad cholesterol”
What is the function of HDL’s?
collect cholesterol from body’s tissues and vascular endothelium (reverse cholesterol transport provides protective effect against heart disease) and brings it back to the liver for excretion – “good cholesterol”
This lipoprotein measurement is an independent inverse risk factor for CAD
Total HDL is an independent inverse risk factor for CAD. Levels < 35 mg/dL increase risk for CAD while levels > 60 mg/dL are protective
This lipoprotein is cholesterol rich and deposits cholesterol in the lining of the blood vessels?
LDLs are cholesterol rich, but most cholesterol carried by LDL gets deposited into the lining of the blood vessels and has increased risk for CAD and peripheral vascular disease. High levels of LDL are atherogenic.
This lipoprotein mainly carrier triglycerides.
VLDL carries small amounts of cholesterol but mainly carries triglycerides.
This lipoprotein can be converted to LDL by lipoprotein lipase in skeletal muscle.
VLDLs are associated with increased risk for CAD as they can be converted to LDL by lipoprotein lipase in skeletal muscle
Interfering factors for Lipoprotein mesaurements.
Smoking and alcohol decrease HDL
Binge eating can alter lipoprotein levels
HDL values are age and sex dependent
HDL values and cholesterol decrease for up to 3 months after an MI
HDL is elevated with hypothyroid and decreased in hyperthyroid
Drugs can alter lipoprotein levels:
Beta blockers increase triglycerides, decrease HDL , decrease LDL size
Alpha blockers decrease triglycerides, increase LDL, increase LDL size
Dilantin increases HDL
Steroids increase triglycerides
Estrogens increase triglycerides
Causes of increased HDL
Familial HDL lipoproteinemia
Excessive exercise – HDL can rise with chronic exercise for 30 minutes 3 times a week
Causes of decreased HDL
Metabolic syndrome – decreased HDL, increased triglycerides, elevated fasting glucose, high blood pressure, and abdominal obesity
Familial low HDL
Hepatocellular disease (hepatitis, cirrhosis) – HDL normally made in liver
Hypoproteinemia (nephrotic syndrome, malnutrition) – HDL not made and levels fall due to loss of proteins
Causes of increased LDL and VLDL
Familial LDL lipoproteinemia
Nephrotic syndrome – loss of protein diminishes plasma oncotic pressures, which stimulates hepatic synthesis of LDL
Glycogen storage diseases – VLDL synthesis increased and excretion decreased
Hypothyroidism – VLDL and LDL catabolism diminished so levels rise
Alcohol consumption
Chronic liver disease (hepatitis, cirrhosis) – liver normally catabolizes LDL
Hepatoma – normal inhibition of LDL synthesis by eating dietary fats doesn’t occur
Gammopathies (multiple myeloma) – high levels of gamma globulins (IgG and IgM) attach to VLDL and LDL to decrease metabolism
Familial hypercholesterolemia – LDL receptors are altered, and LDL is produced at an increased rate
Cushing syndrome – VLDL synthesis is increased and converted to LDL
Apoprotein C-II deficiency – genetic defect with deficiency of lipoprotein lipase, so VLDL and chylomicrons accumulate
Causes of decreased LDL and VLDL
Familial hypoproteinemia
Hypoproteinemia (malabsorption, severe burns, malnutrition)
Hyperthyroidism – catabolism of LDL and VLDL is increased
What is the triglyceride (TG) test used for and what are the normal ranges?
Test is used to identify risk of developing CAD, also part of lipid profile and is performed on patients with suspected fat metabolism disorders
Normal range:
Males 40-160 mg/dL
Females 35-135 mg/dL
What are Triglycerides and where are they produced?
TG are a form of fat in the bloodstream and are transported by VLDL and LDL.
TG is produced in the liver using glycerol and other fatty acids and act as a storage source for energy
When levels are high they are deposited in fatty tissues.
Most of the fat in the body is in what form?
Triglycerides
Interfering factors of triglycerides
Ingestion of fatty meals may elevate TG levels
Alcohol ingestion may elevated TG by increasing production of VLDL
Pregnancy may increase levels
Drugs that increase TG levels are estrogens and oral contraceptives
Drugs that decrease TG levels are ascorbic acid, clofibrate, colestipol, fibrates, and statins
Causes of increased triglycerides
Glycogen storage disease (von Gierke disease) – VLDL synthesis is increased and catabolism decreased
Familial hypertriglyceridemia
Apoprotein C-II deficiency – lipoprotein lipase deficiency leads to TG accumulation
Hyperlipidemias
Hypothyroidism – TG catabolism decreased
High carbohydrate diet – excess carbs converted to TG
Poorly controlled diabetes – increased synthesis of VLDL and decreased catabolism leads to increased TG levels
Nephrotic syndrome – loss of proteins decreases oncotic pressure to stimulate synthesis of VLDL and LDL
Chronic renal failure – high insulin levels as insulin is normally excreted by the kidney. Insulin increases lipogenesis so TG levels rise. Also have deficiency of lipoprotein lipase that clears TG from the blood
Causes of decreased triglycerides
Malabsorption syndrome – poor fat absorption from the GI tract
Abetalipoproteinemia – malabsorption of fat and defective synthesis of apoprotein B (TG carrying lipoproteins)
Malnutrition – diminished fat in the diet
Hyperthyroidism – catabolism of VLDL is increased so TG levels decrease
