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24 Cards in this Set

  • Front
  • Back
What are the major families of lipoproteins?
-Chylomicrons
-VLDL
-IDL
-LDL
-HDL
Describe chylomicrons
-Originate in the intesting from exogenous (dietary) fat and are componsed primarily of triglycerides
-Serve to transport dietary fat from the intestine to sites of utilization and storage in the body
-Usually rapidly shorn of much of their triglyceride through intravascular lipolysis
-Chylomicron remnants are removed by the liver
-Absent from plasma after 12-14 hours of fasting
Describe VLDL
-Originate in the liver and small intestine
-Composed primarily of triglycerides of endogenous origin
-Major function is triglyceride transport
-Cholesterol:triglyceride ratio = 1:5
-15-25g of VLDL triglycerized released into bloodstream daily
-VLDL undergoes rapid lipolysis to a IDL (30% cholesterol, 40% triglyceride) and then to LDL
Describe LDL
-Major product of intravascular metabolism of VLDL
-50% cholesterol by weight
-Removed from blood stream by specific LDL receptors on hepatic and peripheral cells
-Elevation of LDL causes increased risk of coronary heart disease (CHD)
Describe HDL
-Arises from liver and intestin
-Accepts cholesterol and other lipid nad protein fragments from VLDL and chylomicrons during intravascular lipolysis
-Also transports cholesterol from peripheral tissue to the liver (reverse cholesterol transport)
-Involves ABC-A1 and ABC-G1 transporters in peripheral tissues and scavenger receptor B1 (SR-B1) in the liver
-HDL level inversely related to CHD
What is the major carrier of cholesterol in the blood stream?
LDL, transporting 60-75% of the total plasma cholesterol
HDL accounts for less than 25% of the total plasma cholesterol
Describe HDL levels between males nad females
Even in both sexes until pubescence when HDL concentrations in males falls ~20%
What determines HDL and LDL levels?
-Genetics and environment
-Strongest environmental factor is diet
-Diet with high saturated fat and cholesterol cause high LDL
-Higher HDL levels associated with moderate alcohol intake, exercise, and body leanness
-Cigarette smoking, sedentary behaviour, insulinopenic diabetes, and obesity can lower HDL levels
-Blacks have higher HDL levels than white
Describe Lp(a)
-Cholesterol-rich lipoprotein
-Contains apoB-100 covalently linked to a protein with homology to plasminogen
-Plasma levels of Lp(a) associated with prevalent of CHD
-Not modified by dietary maneuvers or by most lipid-altering mediactions
-Levels fall in response to treatment with nicotinic acid or estrogens
How does Lp(a) predispose to CHD
-Delivering cholesterol to the vessel wall
-Interfering with thrombolytic events
-Inhibiting expression of tissue factor
-Carrying pro-inflammatory oxidized phospholipids
What are the categories of LDL levels?
-Optimal (<100 mg/dl)
-Near optimal (100-130 mg/dl)
-Borderline high (130-159 mg/dl)
-High (160-189 mg/dl)
-Very high (>190 mg/dl)
What are the categories of HDL levels?
-Low (<40 mg/dl)
-Normal (40-59 mg/dl)
-High (>60 mg/dl)
What are the three risk categories of LDL levels?
-CHD/10-yr CHD risk >20% (LDL goal <100 mg/dl)
->2 Risk Factors (10-yr risk <10%) (<130 mg/dl)
-0-1 Risk Factor (<160 mg/dl)
Who are in the highest risk category for LDL levels?
-Those who already have developed CHD or who have a 10yr CHD risk similar to those with established CHD
-Other clinical forms of atherosclerosis (perip. arterial disease, abdom. aortic aneurysm, cerebrovascular disease)
-Diabetes mellitus
-Multiple risk factors conferring a 10yr risk of CHD >20%
Who are in the middle risk category for LDL levels?
-Those with at least 2 risk factors for CHD (other than high LDL) conferring 10yr risk <20%
What are the CHD risk factors?
a. Cigarette smoking
b. Hypertension (SBP>140, DBP>90 or taking antihypertensive medication)
c. Low HDL cholesterol (<40mg/dl) (HDL-c>60mg/dl is a negative risk factor, reduced total count by 1)
d. Family history of premature CHD
a. Male first degree relative <55yo
b. Female first degree relative <65yo
e. Age (men>45yo, women>55yo)
What is the primary target in hyperlipidemia treatment? Secondary target?
Primary target: LDL
Secondary target: Non-HDL cholesterol in individuals with fasting triglyceride levels in the 200-499 range
What are the categories of triglyceride levels?
-Normal (<150mg/dl)
-Borderline high (150-199mg/dl)
-High (200-499 mg/dl)
-Very high (>500 mg/dl)
What are some clear reasons to treat elevated triglyceride levels?
-Very high levels pose a risk of pancreatitis and xanthomatosis
-High levels often occur as a manifestation of metabolic syndrome, an atherogenic constellation of effects of obesity and insulin resistance
-High levels reduce concentration of HDL
What should people with low HDL do?
-Exercise
-Achieve and maintain ideal weight
-Cessation of smoking
-Pharmacological measures in patients with CHD or CHD risk equivalent who have HDL <40md/dl
Describe how lipid levels change through time
Serum lipid and lipoprotein concentrations normally increase with age. An acceptable level for cholesterol in a person 40 to 50 years old would be alarmingly high in a 10 yo child
How are cholesterol levels affected by MI?
Serum lipoprotein levels change dramatically immediately and for 6 weeks after a myocardial infarction. The plasma cholesterol, LDL and HDL levels may fall by as much as 60% in the first days after a heart attack
How does one estimate LDL levels
LDL = TC - Tg/5 - HDL
Tg = Fasting triglyceride levels
Tg/5 is an estimate of VLDL
What are the potential causes of secondary hyperlipidemia?
-Diabetes
-Hypothyroidism
-Alcohol use
-Nephrotic syndrome
-Uremia
-Hepatic disease
-Dysglobulinemia
-Porphyria