B P4 C27 Lipoprotein Disorders and Cardiovascular Disease Flashcards
A young patient with eruptive xanthomas and a plasma triglyceride level of 22 mmol/L (2000 mg/dL) probably has _____ as a result of LPL deficiency or other monogenic defects
Familial hyperchylomicronemia
A 38-year-old woman with a strong family history of ASCVD, tendinous xanthomas, and an untreated LDL-C of 240 mg/dL (6.4 mmol/L) likely has _____.
Heterozygous familial hypercholesterolemia (HeFH)
An obese,hypertensive middle-aged man with a cholesterol level of 6.4 mmol/L (245 mg/dL), a triglyceride level of 3.1 mmol/L (274 mg/dL), an HDL-C level of 0.8 mmol/L (31 mg/dL), and a calculated LDL-C level of 4.2 mmol/L (162 mg/dL) probably has _____.
Metabolic syndrome
Affected subjects with FH have an elevated LDL-C level greater than the 95th percentile for age and sex, approximately ____ mg/dL (5.0 mmol/L) in adults.
In adulthood, clinical manifestations include tendinous xanthomas over the _____; corneal arcus and xanthelasma are less specific signs of FH.
190 mg/dL
Extensor tendons (MCP joints, patellar, triceps, and Achilles tendons)
- Transmission: Autosomal codominant
- High risk for the development of CAD by the third to fourth decade in men and approximately 8 to 10 years later in women
- Remarkably, prompt recognition in childhood or early adulthood and treatment (statins) can normalize life expectancy.
Gain-of- function mutations in the _____ gene decrease surface availability of the LDL-R protein and cause accumulation of LDL-C in plasma
PCSK9
- A loss-of-function mutation in PCSK9 confers lower LDL-C than in individuals without the mutation
- Black Americans had a higher prevalence of this protective mutation than did whites in the ARIC (Athero- sclerosis Risk in Communities) study, and subjects with life-long low LDL-C because of a mutation at the PCSK9 gene locus had a marked reduction in coronary events, thus confirming that genetically low LDL-C states lower cardiovascular risk.
A rare condition of increased intestinal absorption and decreased excretion of plant sterols (sitosterol and campesterol) can mimic severe FH with extensive xanthoma formation.
Sitosterolemia
- Premature atherosclerosis, often apparent clinically well before adulthood, occurs in patients with sitosterolemia.
- Diagnosis requires specialized analysis of plasma sterols documenting an elevation in sitosterol, campesterol, cholestanol, sitostanol, and campestanol.
- Patients with sitosterolemia have normal or reduced plasma cholesterol levels, and normal triglyceride concentrations.
- Patients with sitosterolemia have rare homozygous (or compound heterozygous) mutations in the ABCG5 and ABCG8 genes.
Conversely, an obese middle- aged man with a plasma triglyceride level of 7 mmol/L (620 mg/dL) probably has mutations in several genes associated with _____ levels.
Plasma triglyceride levels
Disorders of LDL
Familial hypercholesterolemia
LDLR gene defect
Familial defective ApoB
G-O-F of PCSK9
Polygenic hypercholesterolemia
Nonfasting triglycerides are higher than fasting levels (by approximately 0.3 mmol/L or 27 mg/dL), and guidelines consider nonfasting triglycerides _____ mmol/L (_____ mg/dL) as abnormal, while for fasting triglycerides the corresponding level is _____ mmol/L (_____ mg/dL).
Nonfasting:
> 2 mmol/L
> 175 mg/dL
Fasting:
> 1.7 mmol/L
>150 mg/dL
The 2018 American Heart Association/American College of Cardiology (AHA/ACC) cholesterol guideline and the 2019 AHA/ACC prevention guideline consider fasting or nonfasting triglycerides greater than ____ mg/dL as a risk enhancing factor that could prompt consideration for initiating or intensifying statin therapy.
175 mg/dL
There are some differences in the guideline cutpoints for severe hypertriglyceridemia, defined as fasting triglycerides greater than _____ mmol/L (_____ mg/dL) in European guidelines or _____mg/dL (_____mmol/L) in US guidelines
EU: >10 mmol/L or 885 mg/dL
US: > 5.7 mmol/L or 500mg/dL
Because the triglyceride to cholesterol ratio in TRLs progressively increases as the hypertriglyceridemia becomes more severe, the Friedewald equation (which assumes a fixed triglyceride to cholesterol ratio of triglycerides/5 [mg/dL] or triglycerides/2.2 [mmol/L]) to calculate LDL-C is inaccurate when triglycerides are greater than 4.5 mmol/L (400 mg/dL), as it underestimates the true LDL-C at high triglyceride levels. Instead, it is preferable to use _____ instead of calculated LDL-C for LDL-related treatment decisions in patients with hypertriglyceridemia, as direct LDL-C assays may also be inaccurate
Non-HDL-C or apo B
Primary causes of hypertriglyceridemia: Mild-to-moderate HTG (TG 2.0–9.9mmol/L)
Multifactorial or polygenic HTG (formerly HLP Type 4 or familial HTG)
Complex genetic susceptibility (see above)
Dysbetalipoproteinemia (formerly HLP Type 3 or dysbetalipoproteinemia)
Complex genetic susceptibility (see above), plus
APOE E2/E2 homozygosity or
APOE dominant rare variant heterozygosity
Combined hyperlipoproteinemia (formerly HLP Type 2B or familial combined hyperlipidemia)
Complex genetic susceptibility (see above), plus
Accumulation of common small effect LDL-C-raising polymorphisms
Primary causes of hypertriglyceridemia: Severe HTG (TG >10 mmol/L)
Monogenic chylomicronemia (formerly HLP Type 1 or familial chylomicronemia syndrome)
Lipoprotein lipase deficiency (Bi-allelic LPL gene mutations)
Apo C-II deficiency (Bi-allelic APOC2 gene mutations)
Apo A-V deficiency (Bi-allelic APOA5 gene mutations)
Lipase maturation factor 1 deficiency (Bi-allelic LMF1 gene mutations)
GPIHBP1 deficiency (Bi-allelic GPIHBP1 gene mutations)
Multifactorial or polygenic chylomicronemia (formerly HLP Type 5 or mixed hyperlipidemia)
Complex genetic susceptibility, including
Heterozygous rare large-effect gene variants for monogenic chylomicronemia (see above); and/or
Accumulated common small-effect TG-raising polymorphisms (e.g., numerous GWAS loci including APOA1-C3-A4-A5; TRIB1, LPL, MLXIPL, GCKR, FADS1-2-3, NCAN, APOB, PLTP, ANGPTL3)
Other
Transient infantile HTG (glycerol-3-phosphate dehydrogenase 1 deficiency) from bi-allelic GPD1 gene mutations
______ results from both common and rare genetic variants that result in increased VLDL particles.
Polygenic hypertriglyceridemia (formerly Type IV hyperlipidemia)
- Fasting plasma concentrations of tri- glycerides range between 2.3 to 5.7 mmol/L (200 to 500 mg/dL).
- After a meal, plasma triglycerides may exceed 11.3 mmol/L (1000 mg/dL).
- Polygenic hypertriglyceridemia does not associate with clinical signs such as corneal arcus, xanthoma, and xanthelasmas.
Polygenic hypertriglyceridemia does not associate with clinical signs such as ______.
Corneal arcus, xanthoma, and xanthelasmas
Polygenic hypertriglyceridemia has a weaker relationship with _____ than combined hyperlipoproteinemia (familial combined hyperlipidemia), and not all studies support this association
CAD
Lifestyle modifications should be the first step in treatment of Polygenic hypertriglyceridemia, including:
(1) Weight reduction in overweight individuals
(2) Limiting alcohol intake
(3) Reducing caloric intake
(4) Increasing exercise
(5) Withdrawal of hormones (estrogens and progesterone or anabolic steroids)
An unrelated X–linked genetic disorder,_____, may mimic familial hypertriglyceridemia because most measurement techniques for triglycerides use the measurement of glycerol after enzymatic hydrolysis of triglycerides.
Diagnosis of of this disease requires ultracentrifugation of plasma and analysis of glycerol.
Familial glycerolemia
A less common subset of patients have more severe hypertriglyceridemia which is characterized by a more severe elevation in both VLDL and chylomicrons and are classified as having _____.
Polygenic chylomicronemia (formerly Type V hyperlipidemia)
A rare disorder of HDL deficiency, identified in a proband from Tangier Island in Virginia, Tangier disease and familial HDL deficiency result from mutations in the _____ gene
ABCA1 gene
Reduced plasma levels of _____ consistently correlate with the development or presence of ASCVD
HDL-C
_____ all associate with reduced HDL-C levels.
Monogenic hyperchylomicronemia
Polygenic hypertriglyceridemia
Combined hyperlipoproteinemia
C-H-oMP
Plasma triglyceride and HDL-C levels vary inversely. Several mechanisms contribute to this association:
(1) Decreased lipolysis of TRLs decreases the availability of substrate (phospholipids) for HDL maturation
(2) HDL enriched with triglyceride has an increased catabolic rate and hence reduced plasma concentration
(3) The augmented pool of TRLs saps cholesterol from the HDL compartment by CETP-mediated exchange.
Hypothyroidism often elevates ____ or both.
An increased _____ provides the key to the diagnosis, and the lipoprotein abnormalities often revert to normal after correction of thyroid status.
LDL-C, triglycerides, or both
TSH
Estrogens can elevate plasma _____, because of increases in both hepatic VLDL and apoA-I production.
Triglyceride and HDL-C levels
Oral contraceptives should be avoided in premenopausal women with _____.
In postmenopausal women, estrogens may reduce LDL-C by up to ___%. Use of estrogens for the treatment of lipoprotein disorders is no longer recommended
Premenopausal women with:
* Hypercholesterolemia (LDL-C >4 mmol/L, 160 mg/dL)
* Multiple risk factors
* High thrombotic risk
Postmenopausal women:
15% reduction in LDL-C
Both ____ increase during pregnancy.
Cholesterol and triglycerides
Rarely, pregnancy (particularly in the third trimester) causes severe increases in triglycerides on a background of LPL deficiency or other genetic defects, even if such mutations do not result in dyslipidemia in the non-pregnant state
Male sex hormones and anabolic steroids can increase ______ activity and have been used for the treatment of hypertriglyceridemia in men; however, these agents can also contribute to an elevated triglyceride level, reduced HDL-C, increased blood pressure, and other features of metabolic syndrome.
Hepatic lipase activity
Growth hormone can reduce _____ and increase _____ but is not recommended for the treatment of lipoprotein disorders.
Reduce: LDL-C
Increase: HDL-C
The most frequent secondary cause of dyslipoproteinemia is the constellation of metabolic abnormalities seen in patients with metabolic syndrome.
The finding of _____ and represents the major components of metabolic syndrome
Increased visceral fat (abdominal obesity)
Elevated blood pressure
Impaired glucose tolerance
Increased plasma triglycerides
Reduced HDL-C level
The main cause of dyslipoproteinemia in patients with metabolic syndrome is _____, the substrates for TRL synthesis.
Insulin resistance
Associated increase in FFAs
Overt diabetes, especially type 2 diabetes, frequently elevates plasma _____ and reduces _____.
While LDL-C may be normal or nonelevated due to the excess of small dense LDL particles, increased concentrations of apo B or non-HDL-C are often present and result in a “discordant” lipid profile.
Elevated: TG
Reduced: HDL-C
____ lipodystrophy, a genetic disorder with features of metabolic syndrome, results from mutations within the lamin A/C gene and is associated with limb-girdle fat atrophy. Excess plasma triglycerides often accompany glycogen storage disorders.
Dunnigan lipodystrophy
In patients with glomerulonephritis and protein-losing nephropathies, a marked increase in secretion of hepatic lipoproteins can raise _____, which may approach the levels seen in those with FH.
LDL-C
By contrast, patients with chronic renal failure have a pattern of ______.
Hypertriglyceridemia
Increased small dense LDL particles
Lp(a) - may also be elevated
Reduced:
HDL-C
In the Cholesterol Treatment Trialists meta-analysis of 28 trials of patients with varying degrees of renal impairment, statins reduced cardiovascular risk among patients with _____ chronic kidney disease (estimated glomerular filtration rate >/=30 mL/min/1.73 m2) with smaller benefit among patients with more _____ renal failure, and there was no benefit for patients with _____.
Reduceed CV risk: mild to moderate CKD
Small benefit: advanced renal failure
No benefit: ESRD undergoing dialysis
After organ transplantation, the immunosuppressive regimen (glucocorticoids and cyclosporine) typically elevates _____, reduces ____, and increases _____. Because transplant recipients generally have an increase in cardiovascular risk, this secondary hyperlipidemia may warrant treatment.
Increased:
Triglycerides
VLDL
small dense LDL
Reduced: HDL-C
The Kidney Disease International Improving Outcomes (KDIGO) recommends _____ treatment for patients with chronic kidney disease but does not recommend lipid lowering treatment initiation in patients undergoing long-term dialysis.
Statin or statin plus ezetimibe
Obstructive liver disease, especially primary biliary cirrhosis, may lead to the formation of an abnormal lipoprotein termed _____.
This type of lipoprotein, also associated with LCAT deficiency, consists of an LDL-like particle with a marked reduction in cholesteryl esters.
Extensive xanthoma formation on the ____ areas can result from accumulation of lipoprotein-x.
Lipoprotein-x
Xanthomas of face and palmar areas
Factors contributing to _____, such as an imbalance between caloric intake and energy expenditure, lack of physical activity, and a diet rich in saturated fats and refined sugars, contribute in large part to the lipid and lipoprotein lipid levels within a population.
Obesity
Excessive alcohol intake stimulates _____ and decreased _____.This results in TRL accumulation in the plasma and the liver, and increases hepatic fat accumulation and insulin resistance.
Stimulation of:
Chylomicron and VLDL secretion
VLDL overproduction
Decreased:
LPL activity, and fatty acid oxidation
Several medications can alter lipoproteins:
Thiazide diuretics - increase TG
Beta-blockers (non–beta1-selective agents): increase TG, lower HDL-C
Retinoic acid and estrogens - increase TG.
Corticosteroids and immunosuppressives - increase TG , lower HDL-C.
Estrogens - increase HDL-C and TG.
Anabolic steroids (by endurance or body-building athletes) - hypertriglyceridemia and very low HDL-C.
Atypical antipsychotics -lipoprotein abnormalities, metabolic disorders, and weight gain.
Highly active antiretrovirals - severe lipoprotein disorders and an increase in CAD in patients with chronic human immunodeficiency virus infection
Statins inhibit cholesterol synthesis by inhibiting the enzyme _____ and preventing the formation of mevalonate, the rate-limiting step of sterol synthesis.
HMG- CoA reductase
Atherosclerosis involves inflammation and statins have anti-inflammatory effects. The effect of statins include ____.
(1) Decrease the inflammatory biomarker CRP independent of LDL-C lowering
(2) Augment the collagen content of atherosclerotic plaque
(3) Alter endothelial function
(4) Decrease the inflammatory component of plaque
Statins lower LDL-C in a dose-response manner which is nonlinear: for every doubling of the statin dose, LDL-C drops by about an additional _____%.
6%
Statins vary in intensity from high-intensity (_____) to moderate-intensity (_____) and low-intensity (_____).
High: average lowering of LDL-C by 50%
Atorvastatin 40 to 80 mg/day
Rosuvastatin 20 to 40 mg/day;
Moderate: 30% to 49%
Low: <30%
Statins reduce LDL-C and non-HDL-C more than reducing apo B (by ___<%), triglycerides (by ___%, depending on baseline levels), and may increase HDL-C (by ___%). Statins do not reduce Lp(a)
Reduction:
apo B: 30%
TG: 10-20%
Increase:
HDLC: 1-10%
No reduction: Lp(a)
Statins differ in several aspects including their lipophilicity, plasma protein binding, and absorption, and many statins (except for _____) undergo hepatic metabolism via cytochrome P450 isoenzymes.
Pravastatin
Rosuvastatin
Pitavastatin
PRP - No care sa Liver
Concomitant drugs that interfere with the metabolism of statins by inhibiting the cytochrome P-450 3A4 (which metabolizes ______) and 2C9 can increase plasma concentrations of statins.
Lovastatin
Simvastatin
Atorvastatin
LSA 3A4
Common substances that may interact with statins include:
Amiodarone
Antibiotics (e.g., erythromycin, clarithromycin, rifampin)
Antifungal medications (e.g., azoles)
Antiviral drugs (e.g., lopinavir and ritonavir)
Grapefruit juice
Calcium channel blockers
Colchicine
Cyclosporine
Warfarin
For patients who cannot tolerate daily statin, switching to an alternative appropriate statin with daily dosing (_____ may have less muscle toxicity), or lowering the dose to a small dose of a high-intensity statin every other day or less frequently is usually tolerated and results in considerable LDL-C lowering although outcomes trials have not evaluated this alternate dosing approach.
Pravastatin
Pitavastatin
Fluvastatin
Less muscle/leg work - less P2F
The 2013 ACC/AHA cholesterol guidelines recommended against routine measurement of ___ in all
CK