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MLSCI360 > LIPIDS AND CARDIAC MARKERS > Flashcards

LIPIDS AND CARDIAC MARKERS Flashcards

1
Q

What are lipoproteins ?

A

Proteins that transport lipids in the plasma

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2
Q

What are fatty acids ?

A
  • linear hydrocarbon chains that terminate in a carbonyl group
  • oxidation of free fatty acids = acetyl-CoA enters kerbs cycle for ATP
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3
Q

What are triglycerides ?

A
  • 3 fatty acid molecules + glycerol
  • neutral lipids
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4
Q

What is cholesterol ?

A
  • amphipathic
  • esterified cholesterol (cholesteryl ester) is conjugated to fatty acids = neutral lipid
  • used to synthesize many hormones
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5
Q

What is phospholipids ?

A
  • amphipathic molecule
  • two esterified fatty acids, glycerol, an phospholipid group
  • found in cell membrane
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6
Q

What are apolipoproteins ?

A
  • amphipathic
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7
Q

How are lipoproteins classified ?

A

By density (from least dense):
- chylomicrons
- VLDL
- IDL
- LDL
- HDL
- lipoprotein

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8
Q

As density of lipoproteins increases, the proportion of triglycerides __, and the proportion of cholesteryl ester __.

A

As density of lipoproteins increases, the proportion of triglycerides DECREASES, and the proportion of cholesteryl ester INCREASES.

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9
Q

What are chylomicrons ?

A
  • transport dietary lipids (apolipoprotein B-48) to the liver and peripheral cells
  • largest and least dense lipoprotein
  • forms the creamy layer on top of serum
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10
Q

What are VLDL ?

A

Very Low Density Lipoproteins:
- produced in liver
- carries endogenous triglycerides from liver to peripheral cells (used as energy during fasting)
Ie. apolipoprotein B-100

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11
Q

What are LDL ?

A

Low Density Lipoproteins:
- formed from lipolysis of VLDL
- readily taken up by liver and peripheral cells
- LDL that move into extracellular space of blood vessel walls and ingested by macrophages = foam cells that can develop into atherosclerotic plaques
Ie. apolipoprotein B-100

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12
Q

What are HDL ?

A

High Density Lipoproteins:
- synthesized in liver and intestines
- removes cholesterol away from peripheral cells back to the liver
- anti-atherogenic
Ie. apolipoprotein A-1

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13
Q

Clinical significance of abnormal [lipid]

A
  • coronary heart disease; narrowing of blood vessels
  • atherosclerosis; cholesterol deposits on vessel walls, macrophage invasion, and plaque formation = myocardial infarction, strokes, peripheral vascular disease
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14
Q

Interferences of Triglycerides enzymatic assay

A
  • endogenous free glycerol (corrected by reagent blank)
  • bilirubin, ascorbic acid/ vitamin C (corrected by enzymes)
  • hemolysis = false positive
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15
Q

Sample types for Triglyceride enzymatic assay ?

A
  • 12-hour fasting
  • no alcohol 24 hours prior testing
  • lying down vs standing, exercise = false increase
  • nicotine = false increase
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16
Q

Interferences of Total Cholesterol Enzymatic Assay

A
  • bilirubin and ascorbic acid/ vitamin C reacts with H2O2 = false decrease
  • hemolysis = false positive
17
Q

Sample type for Total Cholesterol Enzymatic Assay ?

A
  • 12-hour fasting
  • laying down vs standing, exercise = false decrease
  • nicotine = false increase
  • prolonged tourniquet use = false increase
18
Q

Why is the HDL cholesterol method advantageous ?

A
  • homogenous assay
  • no pretreatment/ centrifugation required
19
Q

How does the HDL cholesterol method work ?

A
  • detergent solubilizes only HDL lipoproteins and releases HDL cholesterol = reacts with cholesterol esterase/ oxidase to produce a chromogen
  • same detergent also inhibits reactions with LDL, VLDL, and chylomicron lipoproteins by adsorbing to surfaces
  • change in absorbance = DIRECTLY PROPORTIONAL to [cholesterol]
20
Q

Friedewald formula

A

LDL Cholesterol = Total cholesterol - [Triglyceride /2.2] - [ HDL cholesterol]

21
Q

What is a MI ?

A

Myocardial Infarction:
- result of an obstruction in circulatory pathway of heart = necrosis of heart muscle

22
Q

Cardiac marker of MI

A

Troponin

23
Q

What is congestive heart failure ?

A
  • heart is unable to pump blood to maintain oxygenation of tissues
  • characterized by edema due to sodium and water retention, and lack of oxygen
24
Q

Cardiac marker for congestive heart failure

A
  • B-type natriuretic peptide (BNP)
  • NT-pro-BNP
25
Q

What are troponins ?

A
  • cardiac marker for MI
  • TnC, TnT, TnI
  • part of the actin-myosin contractile unit of muscle
26
Q

Which isoforms of troponin are cardiac-specific ?

A

TnT and TnI

27
Q

How are TnT and TnI measured ?

A
  • cardiac-specific troponins are detectable via immunoassay
  • TnI* and TnT approximately rise 2-6 hours after onset of symptoms
  • collection of TnI sample at 0 hours and 6 hours later to rule out MI
  • remains elevated 4-10 days after MI

*more specific to MI

28
Q

Interference for TnI testing

A
  • heparin
  • heterophilic an autoantibodies
  • hemolysis/ fibrin
  • rheumatoid factors
29
Q

What are B-type Natriuretic Peptides ?

A
  • hormones secreted by ventricles of the heart
  • preproBNP cleaved into proBNP cleaved into N-terminal portion (NT-proBNP) and C terminal (active BNP)
  • BNP is a marker of cardiac stretch
  • used for identifying severe congestive heart failure and for risk assessment
30
Q

Sample type for BNP and NT-proBNP testing

A

BNP: EDTA in PLASTIC tube

NT-proBNP: serum or heparin plasma in a glass or plastic tube

31
Q

How are both BNP and NT-proBNP measured ?

A

Via immunoassay

32
Q

BNP level to diagnose heart failure

A

> 500 pg/mL

33
Q

What are CRPs ?

A

C Reactive Protein:
- values above normal but below those seen in infection indicate atherosclerosis, a factor for heart disease

34
Q

How are CRPs measured ?

A

High sensitivity C reactive protein assay (hsCRP assay)

MLSCI360 (22 decks)

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