p.28
Genetic Disorders Related to Lipoproteins
What blood morphology is observed in Sitosterolemia?
Stomatocytes and large platelets.
p.38
Familial Hypercholesterolemia and Its Types
What are the typical HDL levels in individuals with Tangier disease?
Very low or undetectable HDL levels.
p.31
Types of Lipoproteins
What is the consequence of defective LPL in lipoprotein lipase deficiency?
Inability to clear chylomicrons (CMs).
p.15
Types of Lipoproteins
How do lipoproteins compare in density to other macromolecules?
Lipoproteins have lower densities than other macromolecules.
p.15
Types of Lipoproteins
Which lipoprotein classes are the most lipid-rich and buoyant in plasma?
VLDL and chylomicrons (CMs).
p.33
Familial Hypercholesterolemia and Its Types
How are HDL-C levels affected in hepatic lipase deficiency?
They are normal or increased.
p.33
Role of Apolipoproteins
What ability do patients with hepatic lipase deficiency have regarding VLDL?
They can convert large VLDL to smaller VLDL particles.
p.29
Familial Hypercholesterolemia and Its Types
What is the condition of LDL receptors in Autosomal-Recessive Hypercholesterolemia?
LDLR is normal but LDL clearance is low.
p.17
Measurement of Cholesterol and Triglycerides
What happens to cholesterol estimation in VLDL with high triglyceride concentrations?
It leads to overestimation of cholesterol in VLDL and underestimation of calculated LDL-C.
p.16
Types of Lipoproteins
Which lipoprotein is the fastest during electrophoresis?
HDL; it moves with alpha1-globulins.
p.18
Measurement of Cholesterol and Triglycerides
What is the function of Reagent 2 in direct LDL-C measurement?
Releases cholesterol from LDL to be measured enzymatically.
What is the primary function of VLDL?
To supply tissues with triglycerides of endogenous origin and cholesterol.
p.29
Statin Therapy and Its Indications
Which medications are used to treat Autosomal-Dominant Hypercholesterolemia?
Statins, Alirocumab, and Evolocumab.
p.15
Types of Lipoproteins
What is the basis for the separation of different lipoprotein classes?
Different densities of each lipoprotein class.
p.1
Lipids and Their Solubility
How do lipids behave in polar solvents?
They are relatively insoluble in polar solvents (like water).
What is HDL primarily composed of?
Mostly of protein, cholesterol, and phospholipids.
p.18
Measurement of Cholesterol and Triglycerides
What is the purpose of direct LDL-C measurement?
It is useful when triglycerides are elevated and not subject to interference by triglycerides.
p.31
Familial Hypercholesterolemia and Its Types
What symptoms do children with lipoprotein lipase deficiency typically present?
Abdominal pain and pancreatitis.
p.29
Familial Hypercholesterolemia and Its Types
What is the effect of the PCSK9 gene mutation on LDL cholesterol levels?
Increased plasma LDL-C and increased risk of coronary heart disease (CHD).
p.32
Genetic Disorders Related to Lipoproteins
What factors can affect ApoC-III levels?
Age, alcohol consumption, and oral contraceptive use.
p.22
Statin Therapy and Its Indications
Which age group with diabetes should consider statin therapy?
Individuals 40 to 75 years of age with LDL-C 70 to 189 mg/dL without clinical ASCVD.
p.3
Role of Apolipoproteins
What is the function of HDL?
To perform reverse cholesterol transport, returning excess cholesterol from tissues to the liver.
How is VLDL hydrolyzed?
By lipoprotein lipase (LPL).
p.17
Measurement of Cholesterol and Triglycerides
What is the Friedewald formula for LDL-C?
LDL-C = [Total Cholesterol] – [HDL-C] – VLDL.
p.33
Role of Apolipoproteins
What conversion is impaired in patients with hepatic lipase deficiency?
Conversion of VLDL to IDL and LDL from IDL.
p.18
Measurement of Cholesterol and Triglycerides
What does Reagent 1 do in the direct LDL-C measurement process?
Removes non-LDL lipoproteins and inhibits LDL from reacting with enzymes.
p.38
Genetic Disorders Related to Lipoproteins
What is the primary dysfunction in Tangier disease?
Inability to transfer cholesterol and phospholipids from within the cell onto nascent apoA1 proteins in the plasma.
p.32
Genetic Disorders Related to Lipoproteins
In which conditions are ApoC-III levels increased?
In diabetes mellitus type 2, hyperbilirubinemia, kidney deficiency, and thyroid dysfunction.
p.19
Role of Apolipoproteins
What is the best single measurement to predict coronary artery disease risk?
Apolipoprotein measurement (ApoA-I and ApoB).
p.20
Role of Apolipoproteins
How is oxLDL taken up by cells?
By scavenger receptors in macrophages.
p.1
Lipids and Their Solubility
In which type of solvents are lipids soluble?
Nonpolar organic solvents (like chloroform and ether).
p.20
Measurement of Cholesterol and Triglycerides
What does oxLDL serve as a marker for?
Coronary Heart Disease (CHD).
p.17
Measurement of Cholesterol and Triglycerides
Why is the Friedewald formula unsuitable for nonfasting samples?
Because they may contain chylomicrons (CMs) or B-VLDL.
p.35
Role of Apolipoproteins
What happens to apoB in Abetalipoproteinemia?
It is misfolded and destroyed by the endoplasmic reticulum.
p.1
Role of Apolipoproteins
What are apolipoproteins?
The protein moiety of lipoproteins, arrayed on the surface.
p.34
Metabolic Syndrome Criteria
What are the components of metabolic syndrome?
Visceral adipose tissue, insulin resistance, and dyslipidemia.
p.22
Statin Therapy and Its Indications
What LDL-C level qualifies for statin therapy?
Primary elevations of LDL-C of 190 mg/dL or higher.
p.20
Types of Lipoproteins
What is oxLDL?
Modified lipoprotein in the form of oxidized LDL.
p.29
Familial Hypercholesterolemia and Its Types
What gene mutation is associated with Autosomal-Recessive Hypercholesterolemia?
ARH (LDLRAP1) gene mutation.
p.36
Familial Hypercholesterolemia and Its Types
What is the effect of hypobetalipoproteinemia on cardiovascular disease risk?
Decreased risk for cardiovascular disease.
p.20
Genetic Disorders Related to Lipoproteins
What is the main source of oxLDL?
ROS-induced lipid peroxidation and lipoxygenase.
p.27
Familial Hypercholesterolemia and Its Types
What are common clinical manifestations of Familial defective ApoB?
Tendinous xanthomas, xanthelasma, and premature coronary disease.
p.9
Specimen Considerations for Lipid Testing
What is considered abnormal regarding chylomicrons after fasting?
Presence of chylomicrons after a 12-hour fast.
p.35
Familial Hypercholesterolemia and Its Types
What vitamin deficiencies occur due to malabsorption in Abetalipoproteinemia?
Fat-soluble vitamins A, K, and E.
p.12
Measurement of Cholesterol and Triglycerides
What is a potential interference in the cholesterol measurement?
Cholesterol oxidase can react with other sterols, such as plant sterols.
p.9
Specimen Considerations for Lipid Testing
How long should tourniquets be applied during blood sampling?
No longer than 1 to 2 minutes.
p.24
Familial Hypercholesterolemia and Its Types
What are the cholesterol levels for heterozygous and homozygous familial hypercholesterolemia?
Heterozygous: >200 mg/dL; Homozygous: >400 mg/dL.
p.4
Chylomicrons and Their Function
What is the primary function of chylomicrons?
To transport lipids of dietary origin to the tissues.
What does VLDL stand for?
Very Low-Density Lipoprotein.
p.13
Measurement of Cholesterol and Triglycerides
What do triglycerides measure based on?
The hydrolysis measurement of glycerol.
p.38
Genetic Disorders Related to Lipoproteins
What are some clinical features of Tangier disease?
Hepatosplenomegaly, peripheral neuropathy, orange tonsils, and premature coronary disease.
p.30
Familial Hypercholesterolemia and Its Types
What are the typical triglyceride levels in familial hypertriglyceridemia?
TGs ranging from 200 to 500 mg/dL.
p.27
Familial Hypercholesterolemia and Its Types
How does Familial defective ApoB affect LDLR?
It interferes with the recognition of apoB-100 by the LDL receptor (LDLR).
p.33
Types of Lipoproteins
What is notable about HDL and LDL particles in hepatic lipase deficiency?
They are enriched with triglycerides.
p.10
Specimen Considerations for Lipid Testing
How long can samples be stored at 4 °C until analyzed?
Indefinitely, as long as they are not in contact with cells overnight.
p.35
Role of Apolipoproteins
What apolipoproteins are absent in the plasma of individuals with Abetalipoproteinemia?
Neither apoB-48 nor apoB-100.
p.17
Measurement of Cholesterol and Triglycerides
What does the Martin-Hopkins formula improve?
Accuracy for LDL-C determination.
What are the main types of lipoproteins?
Chylomicrons (CM), Very Low Density Lipoproteins (VLDL), Low Density Lipoproteins (LDL), and High Density Lipoproteins (HDL).
p.31
Genetic Disorders Related to Lipoproteins
What is defective or absent in lipoprotein lipase deficiency?
Lipoprotein lipase (LPL).
p.3
Role of Apolipoproteins
What is the primary function of ApoB-containing lipoproteins?
To deliver lipids to tissues for storage and energy use.
p.27
Familial Hypercholesterolemia and Its Types
What type of genetic disorder is Familial defective ApoB?
An autosomal-dominant disorder.
p.17
Measurement of Cholesterol and Triglycerides
What is the Friedewald formula used for?
To calculate LDL-C levels.
p.20
Chylomicrons and Their Function
What process leads to lipid accumulation and foam cell formation?
The uptake of oxLDL by macrophages.
p.28
Genetic Disorders Related to Lipoproteins
What cardiovascular condition is associated with Sitosterolemia?
Premature atherosclerosis.
p.27
Familial Hypercholesterolemia and Its Types
What type of mutation is involved in Familial defective ApoB?
A missense mutation in the LDLR-binding domain.
p.1
Role of Apolipoproteins
What is the characteristic of free cholesterol?
It has a hydrophilic surface.
p.9
Specimen Considerations for Lipid Testing
What are chylomicrons (CMs) usually produced after?
Meals, leading to increased triglycerides (TG).
What is found in the hydrophobic core of lipoproteins?
Cholesteryl esters and triglycerides.
What is the primary function of HDL?
Reverse cholesterol transport.
What are some of the protective functions of HDL?
Anti-inflammatory, antioxidant, antithrombotic, and nitric oxide-producing.
p.14
Types of Lipoproteins
What is the most abundant phospholipid in the body?
Phosphatidylcholine (70%-75%).
p.29
Familial Hypercholesterolemia and Its Types
What type of mutation is associated with Autosomal-Dominant Hypercholesterolemia?
Gain of function mutation of the PCSK9 gene.
p.36
Genetic Disorders Related to Lipoproteins
What type of mutation is associated with hypobetalipoproteinemia?
Missense mutation in the apoB gene.
p.37
Familial Hypercholesterolemia and Its Types
What must be absent to diagnose familial hypoalphalipoproteinemia?
Disease or factors leading to secondary effects of hypoalphalipoproteinemia.
p.28
Genetic Disorders Related to Lipoproteins
Which gene mutations are involved in Sitosterolemia?
ABCG8 or ABCG5 gene mutations.
p.30
Familial Hypercholesterolemia and Its Types
What is increased in familial hypertriglyceridemia that affects VLDL?
VLDL triglyceride production.
p.17
Measurement of Cholesterol and Triglycerides
How is VLDL calculated in mmol/L?
VLDL = [Plasma TG/2.175].
Why is LDL considered atherogenic?
Because it contributes to the formation of atherosclerosis.
p.12
Measurement of Cholesterol and Triglycerides
What is the Abell-Kendall method used for?
It is a reference method for measuring cholesterol.
p.25
Statin Therapy and Its Indications
What is the mechanism of action of Mipomersen?
Inhibits production of apoB-100.
p.16
Types of Lipoproteins
Where does VLDL move during electrophoresis?
Intermediate between LDL and HDL; moves with B2-globulins.
p.24
Familial Hypercholesterolemia and Its Types
What happens in Class II familial hypercholesterolemia?
LDLR is not properly transported.
p.32
Role of Apolipoproteins
What is the effect of excess ApoC-III on LPL activity?
It interferes with the activity of LPL.
p.37
Familial Hypercholesterolemia and Its Types
What are the HDL-C level thresholds for men and women with familial hypoalphalipoproteinemia?
Less than 30 mg/dL in men and less than 40 mg/dL in women.
p.25
Familial Hypercholesterolemia and Its Types
What are some signs and symptoms of hypercholesterolemia?
Corneal arcus, xanthomas, xanthelasma.
p.8
Role of Apolipoproteins
Where is ApoA-I produced?
In the liver and small intestine.
p.35
Chylomicrons and Their Function
Does vitamin D require chylomicrons for absorption?
No, it does not require chylomicrons.
p.12
Measurement of Cholesterol and Triglycerides
How does ascorbic acid affect cholesterol measurement?
It competes with chromogenic substrates, leading to lowered levels.
p.23
Familial Hypercholesterolemia and Its Types
What is polygenic hypercholesterolemia?
Hypercholesterolemia from multifactorial causes.
p.11
Specimen Considerations for Lipid Testing
Why should specimens not be stored in self-defrosting freezers?
Because the freeze-thaw cycle enhances specimen deterioration.
p.23
Familial Hypercholesterolemia and Its Types
How does age affect cholesterol levels in polygenic hypercholesterolemia?
There are age-related increases in cholesterol that do not respond to lifestyle modification.
p.34
Metabolic Syndrome Criteria
How many criteria must be met to diagnose metabolic syndrome?
Three or more of the specified criteria.
p.37
Familial Hypercholesterolemia and Its Types
What familial pattern is considered in the diagnosis of familial hypoalphalipoproteinemia?
Presence of a similar lipoprotein pattern in a first-degree relative.
How is LDL produced?
Through the metabolism of VLDL (Very Low-Density Lipoprotein) and IDL (Intermediate-Density Lipoprotein).
What forms do lipids take when complexed with lipoproteins?
Cholesterol and triglycerides.
p.10
Specimen Considerations for Lipid Testing
What should be done with blood samples after drawing?
Cool in an ice bath immediately.
p.7
Role of Apolipoproteins
What is the function of ApoB-100?
It acts as a ligand for hepatic LDL receptors (LDLRs).
p.17
Measurement of Cholesterol and Triglycerides
What is the triglyceride concentration threshold that makes the Friedewald formula unsuitable?
Greater than 200 to 400 mg/dL.
p.16
Types of Lipoproteins
Which lipoprotein is the slowest during electrophoresis?
LDL; it moves with beta-globulins.
p.12
Measurement of Cholesterol and Triglycerides
How are the byproducts of the Abell-Kendall method quantified?
By measuring hydrogen peroxide from the cholesterol oxidase reaction.
p.12
Measurement of Cholesterol and Triglycerides
What role does hemoglobin play in cholesterol measurement?
It exhibits pseudoperoxidase activity, leading to elevated levels.
p.32
Role of Apolipoproteins
How does ApoC-III affect the binding of lipoproteins?
It binds to the carboxy-terminal of ApoB, preventing binding of lipoproteins to the LDLR.
p.13
Measurement of Cholesterol and Triglycerides
What does each glycerol molecule represent?
One triglyceride molecule.
p.37
Familial Hypercholesterolemia and Its Types
What is one of the criteria for diagnosing familial hypoalphalipoproteinemia?
Low HDL in the presence of normal VLDL and LDL cholesterol.
p.29
Role of Apolipoproteins
What role does PCSK9 play in cholesterol metabolism?
It leads to intracellular degradation of LDL receptors (LDLR).
p.14
Specimen Considerations for Lipid Testing
What is required for the estimation of lipid phosphorous?
Lipid extraction from the sample.
p.28
Genetic Disorders Related to Lipoproteins
What is the consequence of ABCG8 or ABCG5 mutations?
Disruption of the channel to pump back absorbed plant sterols into the intestinal lumen.
What are the main components of LDL?
Cholesterol (50%), Protein (25%), and Phospholipid (20%).
p.25
Statin Therapy and Its Indications
What is the desired response to therapy for LDL-C levels?
Achieve LDL-C reduction of 50% or more from baseline.
p.25
Statin Therapy and Its Indications
What is the mechanism of action of Lomitapide?
Inhibits MTP, decreasing LDL production.
p.16
Measurement of Cholesterol and Triglycerides
What stains are used to visualize lipoproteins in electrophoresis?
Oil Red O, Fat Red 7B, or Sudan Black B.
p.9
Specimen Considerations for Lipid Testing
What effect does prolonged venous occlusion have on cholesterol levels?
It can increase cholesterol levels by 10% to 15%.
p.24
Familial Hypercholesterolemia and Its Types
What occurs in Class IV familial hypercholesterolemia?
LDLR bound to LDL does not properly cluster in clathrin-coated pits for endocytosis.
What are the two forms of cholesterol contained in lipoproteins?
Free cholesterol and cholesteryl ester.
p.10
Specimen Considerations for Lipid Testing
Is there more or less protein aggregation in serum compared to plasma?
Less protein aggregation in serum.
p.35
Measurement of Cholesterol and Triglycerides
What laboratory findings are associated with Abetalipoproteinemia?
Decreased apoB, triglycerides (TGs), and total cholesterol (TC).
p.24
Familial Hypercholesterolemia and Its Types
What is the consequence of LDLR gene mutations?
Loss of LDLR activity in the clearance of LDL-C.
p.24
Statin Therapy and Its Indications
What is the mechanism of action of statins?
Inhibit HMG-CoA reductase.
p.17
Measurement of Cholesterol and Triglycerides
What does the Martin-Hopkins formula apply to the TG:VLDL-C ratio?
An adjustable factor based on TG and non-HDL-C concentrations.
p.9
Specimen Considerations for Lipid Testing
How long should patients be seated before sampling?
For 5 minutes to prevent hemoconcentration.
p.35
Familial Hypercholesterolemia and Its Types
What effect does vitamin E replacement have in Abetalipoproteinemia?
It improves retinal and peripheral neuropathy.
p.34
Metabolic Syndrome Criteria
What are the blood pressure criteria for hypertension in metabolic syndrome?
Systolic > 130 mmHg; Diastolic > 85 mmHg.
p.24
Statin Therapy and Its Indications
Name two examples of statins.
Atorvastatin and Simvastatin.
p.4
Chylomicrons and Their Function
What do chylomicrons primarily consist of?
Very rich in triglycerides but very poor in free cholesterol, phospholipids, and protein.
p.9
Specimen Considerations for Lipid Testing
Can total cholesterol (TC) and HDL-C be measured in non-fasting samples?
Yes, they can be measured in non-fasting samples.
p.9
Specimen Considerations for Lipid Testing
What requires fasting for accurate measurement?
Triglycerides (TG) and LDL-C.
p.24
Familial Hypercholesterolemia and Its Types
What characterizes Class I familial hypercholesterolemia?
LDLR is not synthesized at all.
p.24
Familial Hypercholesterolemia and Its Types
What is the issue in Class III familial hypercholesterolemia?
LDLR does not properly bind LDL.
p.4
Chylomicrons and Their Function
What role does ApoC-II play in relation to chylomicrons?
It is an activator of lipoprotein lipase.
p.4
Chylomicrons and Their Function
How are chylomicron remnants removed by the liver?
Through interaction of apoE with LDLR.
p.24
Familial Hypercholesterolemia and Its Types
What causes familial hypercholesterolemia?
Mutations in the LDLR gene.
What is the role of CETP in HDL metabolism?
Transfers triglycerides from B-LPs into HDL and cholesteryl esters from HDL to B-LPs for clearance.
p.12
Measurement of Cholesterol and Triglycerides
What effect does bilirubin have on cholesterol measurement?
It increases measured cholesterol values due to light absorbance.
p.4
Chylomicrons and Their Function
What happens to triglycerides during the interaction of chylomicrons with lipoprotein lipase (LPL)?
Depletion of triglycerides occurs, leading to chylomicron remnants.
p.24
Familial Hypercholesterolemia and Its Types
What is the problem in Class V familial hypercholesterolemia?
LDLR is not recycled back to the cell surface.
