Cholesterol Levels and Influencing Factors

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Questions and Answers

What is recommended for patients before measuring lipoproteins?

Maintaining their usual diet for 2 weeks without gaining or losing weight (correct)

Engaging in strenuous exercise for 1 week

Following a very low-fat diet for 1 week

Fasting for 24 hours

Why should lipoproteins measurement be delayed after child birth?

Because of the recovery period

To minimize the effect of childbirth on lipoprotein levels (correct)

Because of hormonal changes

Because of changes in diet

What is true about season and cholesterol levels?

Cholesterol levels are slightly higher in cold periods (correct)

Cholesterol levels decrease in cold periods

Cholesterol levels increase in warm periods

Cholesterol levels remain constant throughout the year

What is the product of the Lierbermann-Burchardt Reaction?

Bluish green solution Signup and view all the answers

How long should lipoproteins measurement be delayed after acute illness?

At least 8 weeks Signup and view all the answers

What is the primary cause of Arteriosclerosis?

Deposition of esterified cholesterol in artery walls Signup and view all the answers

What is the primary characteristic of Familial Hypercholesterolemia?

Elevated cholesterol associated with increased LDL Signup and view all the answers

What is a factor that increases cholesterol levels?

Daily intake of high amounts of fat Signup and view all the answers

What is a lifestyle factor that increases cholesterol levels?

Sedentary lifestyle and poor diet habits Signup and view all the answers

Which method is used to extract cholesterol in the Bloors Method?

Alcohol ether mixture Signup and view all the answers

What is the enzymatic method used to measure cholesterol?

Cholesteryl oxidase Signup and view all the answers

What is the term for elevated levels of cholesterol in the blood?

Hypercholesterolemia Signup and view all the answers

What is the preferred sample for lipid tests?

Serum Signup and view all the answers

What is the required fasting period for a fasting lipid test?

12 hours Signup and view all the answers

What is the name of the enzyme that serves as a good marker of extra hepatobiliary disorders?

Alkaline Phosphatase (ALP) Signup and view all the answers

What is the component of cell membranes and a precursor for steroid hormones and bile acids synthesized by body cells?

Cholesterol Signup and view all the answers

What is the recommended dilution ratio for samples exceeding the measuring range?

1:4 with NaCl solution (9 g/L) Signup and view all the answers

In which condition are ALP levels physiologically increased?

Pregnancy Signup and view all the answers

What is the purpose of centrifugation at 4000 r.p.m. for 20 minutes?

To separate the supernatant from the precipitate Signup and view all the answers

What is the term for the complexes between lipids and apolipoproteins?

Lipoproteins Signup and view all the answers

What are the five major classes of lipoproteins?

Chylomicrons, HDL, LDL, VLDL, IDL Signup and view all the answers

What is the unit of measurement for HDLc concentration in the sample?

mg/dL Signup and view all the answers

What is the term for the elevation in the test that would most likely suggest cholestasis?

Alkaline Phosphatase (ALP) Signup and view all the answers

What is the recommended incubation period at room temperature?

10 minutes Signup and view all the answers

What is the limit of detection for triglycerides in this assay?

2 mg/dL Signup and view all the answers

What is the wavelength used for calculating HDLc concentration?

546 nm Signup and view all the answers

What is the recommended centrifugation speed for 2 minutes?

12000 r.p.m. Signup and view all the answers

What is the purpose of adding R (Precipitating Reagent)?

To precipitate the lipoproteins Signup and view all the answers

What is the unit conversion factor to convert mg/dL to mmol/L?

0.02586 Signup and view all the answers

What is the borderline high risk range for cholesterol levels in mmol/L?

5.2-6.2 mmol/L Signup and view all the answers

What is the lower limit of detection for the cholesterol test in mg/dL?

3 mg/dL Signup and view all the answers

What is the composition of the NaCl solution used for dilution in the cholesterol test?

9 g/L Signup and view all the answers

What is the consequence of a severe increase in Triglyceride levels?

Atherosclerotic cardiovascular disease Signup and view all the answers

What is the concentration of Good's Buffer in the reagent composition?

50 mmol/L Signup and view all the answers

What is the effect of a combination of genetic factors and increased production of Triglycerides?

Elevated risk of atherosclerotic cardiovascular disease Signup and view all the answers

What is the concentration of ATP in the reagent composition?

2 mmol/L Signup and view all the answers

Study Notes

Cholesterol and Lipid Metabolism

Cholesterol levels are slightly higher in cold periods.
Factors affecting cholesterol levels:
- Food intake: daily intake of fat increases cholesterol levels.
- Acute illness: lipoprotein measurement should be made no sooner than 8 weeks after any form of trauma or acute bacterial/viral infection, and 3-4 months after childbirth.
- Life-style: higher in sedentary and poor diet habits.
Measurement of cholesterol:
- L-B reaction: cholesterol + sulfuric acid + acetic anhydride = bluish green solution.
- Liebermann-Burchardt Reaction.
- Enzymatic method: cholesteryl oxidase.
- Bloors Method: 2-step principle, extracting cholesterol using an alcohol ether mixture.

Lipoprotein Physiology and Metabolism

Arteriosclerosis: deposition of esterified cholesterol in artery walls, leading to CAD, PVD, and CVD.
Dyslipidemia:
- Hypolipoproteinemia
- Hyperlipoproteinemia
- Hypercholesterolemia
- Hypertriglyceridemia
- Combined hyperlipidemia
Familial hypercholesterolemia: elevated cholesterol associated with increased LDL due to genetic abnormalities.

Specimen Collection and Cholesterol Determination

Serum is the preferred sample, which can be tested in a non-fasting or fasting state.
Fasting lipid test requires a 12-hour fast, except for water.
Cholesterol is a component of cell membranes and a precursor for steroid hormones and bile acids.
Cholesterol is transported in plasma via lipoproteins.

Computation and Unit Conversion

Conversion: mg/dL x 0.02586 = mmol/L
Reference range:
- Desirable: ≤ 200 mg/dL (5.2 mmol/L)
- Borderline high risk: 200-240 mg/dL (5.2-6.2 mmol/L)
- High risk: > 240 mg/dL (> 6.2 mmol/L)

Triglyceride Determination

Elevated triglyceride levels increase the risk of pancreatitis and atherosclerotic cardiovascular disease.
Factors affecting triglyceride levels:
- Genetic factors
- Increased production and/or impaired clearance of triglycerides
Measurement of triglycerides:
- Enzymatic method
- Reference range:
 - Desirable (fasting): < 200 mg/dL (< 2.3 mmol/L)
 - Borderline high: 200-400 mg/dL (2.3-4.5 mmol/L)
 - Elevated: > 400 mg/dL (> 4.5 mmol/L)

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Description

This quiz covers the factors that influence cholesterol levels, including seasonal changes, diet, and fasting. Learn how these factors impact cholesterol levels and triglyceride levels.