Lipids Flashcards
What are the main reasons to assess lipids?
- diagnose lipid/lipoprotein metabolism disorders
- Diagnose lipid storage disorders/mitochondrial oxidation disorders
- cardiovascular risk assessment
ON THE TEST: WHat were the data points used in the traditional framingham risk score?
age, gender, smoking status, total cholesterol, HDL, systolic BP and HTN Rx
Where do most patients fall in the framingham risk score? Why is this an issue?
76% fell in the low risk category, but people in this category still had CV events
What do we use now instead of framingham?
the 2013 ACC/AHA guidelines, which has new pooled cohort equations for ASCVD risk assessment with different equations for nonwhite populations
Statin therapy is recommended in what 4 groups under the ACC/AHA guidelines?
- Diabetics
- LDL > 190
- ASCVD risk > 7.5% with LDL 70-189
- Secondary prevention in other high risk groups ??
True or false: the ACC/AHA guidelines have no LDL or non-HDL treatment targets
true
What risk factors are taken into account for the ACC/AHA ASCVD risk calculator?
sex, age, race, total chol, HDL, SBP, BP treatment, Diabetes, Smoker status
What are the 6 major classes of lipoproteins?
chylomicrons VLDL IDL LDL HDL Liproprotein A
Which lipoprotein particle is the causal agent in atherosclerosis?
LDL particle - the more LDL a person has, the higher the risk for plaque buildup
Is LDL cholesterol and LDL particle?
No - LDL cholesterol is just the cholesterol that makes up the LDL particle. As such, it’s not a perfect measure of LDL and LDL_attributable risk
Reduction in LDL cholesterol by 40 mg/dL reduces CHD risk by ___%
20%
What is the optimal LDL liprotein level?
50-70 mg/DL
There is NO atherosclerosis progression at LDL-C < 67 mg/dL
ON THE TEST: What equation is the most common method for reporting LDL?
The Friedewald equation, which assumes al cholesterol is VLDL, LDL and HDL
cLDL = [Tot Chol] - [HDL chol] - [Tg]/5
When should the Friedewald equation not be used?
when the TG > 400 because it assumed chylomicrons, IDL and liporpotein A are not signficant, but if you have a TG > 400, you definitely have some chylomicrons floating around
If someone does have elevated TGs, what is a better number to use for risk prediction beyond the LDL-C?
the non-HDL-c
What are the two primary reasons to perform lipid screening in pediatrics?
- identify childhood dyslipidemia (in pediatric obesity and T2DM)
- ID genetic hyperlipidemia (with fam hx of early CV)
note: we can differentiate normal lipids from abnormal lipid by age 2
Describe familial hypercholesterolemia.
an inheritable, AD disorder of mutation in the LDL receptor; resulting in severe hypercholesterolemia present starting in chldhood with CVD early in life
one of the most commonly occurring genetic disorders (1:200 to 500)
What LDL level would you expect with a heterozyote FH? Homozygote?
hetero > 190
Homo > 600-1000
How can cholesterol testing be used to make a phenotypic diagnosis of FH?
> 190 makes it likely
160 with positive family hx
135 with positive genetic dx in family
What secondary causes should be ruled out before you move to genetic testing for FH
thyroid disease liver disease renal disease medication effect obesity
Ideally, when should you screen for discrimination of FH?
in childhood! Lipid screening is most effective in early childhood (ages 1-9)
Should we universally screen all children ages 1-9 then?
Hard to say. Some organizations say yes. USPSTF says inconclusive.
If strong family hx of early CV or physical findings of FH in the child, consider screening as early as age 2
In adult HF patients, what is the treatment titration goal?
get an LDL-C reduction of at least 50% from baseline
What is the treatment strategy to get to this goal?
start with mod to high statin monotherapy
then add ezetimibe
then add things like bile acid sequestrants, fibrates, nicotinic acids
apheresis is last resort for treatment in heterozygous FH, but actually a first-line therapy in homozygous FH because it won’t respond to drugs or lifestyle modifications
ON THE TEST: Apo-A1 is associated which which lipoproteins? Functioning as what?
HDL - part of HDL structure
Chylomicrons: LCAT ativator
ON THE TEST: Apo-B100 is associated with what lipoproteins? Functioning as what?
VLDL, IDL, LDL
It binds the LDL receptor and is part of structure for all three
ON THE TEST: ApoB48 is associated with which lipoprotein? Function?
Chylomicron - structural
ON THE TEST: What are the two most common hyperlipidemia phenotype in the US?
IV (45%)
IIb (40%)
ON THE TEST: Describe phenotype I. WHat’s elevated?
Mainly chylomicrons
so plasma cholesterol level is up, triglycerid level is waaay up
ON THE TEST: Describe phenotype IIa. What’s up?
LDL is up
so plasma cholesterol is high but TGs are normal. very high athero-genicity
ON THE TEST: Describe phenotype IIb. What’s up?
LDL and VLDL
so high cholesterol, high TGs and high athero-genicity
ON THE TEST: Describe phenotype III. WHat’s up?
IDL
high cholesterol and very high TGs; high ahtero-genicity
ON THE TEST: Describe phenotype IV. What’s up?
VLDL
normal to high plasma cholesterol. mildly elevated TGs. relatively low athero-genicity
ON THE TEST: Describe phenotype V. What’s up?
VLDL and chylomicrons
so mildly increased cholesterol, very high TGs. relatively low athero-genicity
What phenotype is familial hypercholesterolemia?
IIa
