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Questions and Answers
What is included in a typical lipid profile?
What is included in a typical lipid profile?
- HDL cholesterol, triglycerides, vitamin D, and LDL cholesterol
- Total cholesterol, HDL cholesterol, triglycerides, and LDL cholesterol (correct)
- Total cholesterol, triglycerides, vitamin K, and HDL cholesterol
- Total cholesterol, HDL cholesterol, triglycerides, and blood glucose
What role does cholesterol play in the body?
What role does cholesterol play in the body?
- It helps in the absorption of vitamins exclusively
- It supports the production of hormones and aids in digestion (correct)
- It is used solely for cell membrane structure
- It mainly acts as an energy source for cells
What percentage of cholesterol in the body is synthesized by the liver?
What percentage of cholesterol in the body is synthesized by the liver?
- 70% (correct)
- 50%
- 30%
- 100%
What is LDL cholesterol known as?
What is LDL cholesterol known as?
Which of the following is true regarding HDL cholesterol?
Which of the following is true regarding HDL cholesterol?
What health condition is associated with high levels of LDL cholesterol?
What health condition is associated with high levels of LDL cholesterol?
Which of the following foods is likely to contribute to higher cholesterol levels?
Which of the following foods is likely to contribute to higher cholesterol levels?
What is the primary target for cholesterol-lowering medications?
What is the primary target for cholesterol-lowering medications?
What is the incubation time at 37 oC for the sample and standard?
What is the incubation time at 37 oC for the sample and standard?
At what wavelength should the absorbance be measured?
At what wavelength should the absorbance be measured?
What is the appropriate procedure after mixing the precipitant and sample?
What is the appropriate procedure after mixing the precipitant and sample?
Which lipoproteins are targeted for precipitation in the HDL cholesterol estimation?
Which lipoproteins are targeted for precipitation in the HDL cholesterol estimation?
What is the total volume of the standard used in the HDL estimation procedure?
What is the total volume of the standard used in the HDL estimation procedure?
What is the temperature condition for incubation at room temperature?
What is the temperature condition for incubation at room temperature?
What is the main enzyme used to hydrolyze cholesterol esters in serum?
What is the main enzyme used to hydrolyze cholesterol esters in serum?
What is produced when cholesterol is oxidized by cholesterol oxidase?
What is produced when cholesterol is oxidized by cholesterol oxidase?
What substance is used for the precipitation of lipoproteins?
What substance is used for the precipitation of lipoproteins?
What is done with the supernatant after centrifuging?
What is done with the supernatant after centrifuging?
What is the final product of the reaction that involves hydrogen peroxide, phenol, and 4-aminoantipyrine?
What is the final product of the reaction that involves hydrogen peroxide, phenol, and 4-aminoantipyrine?
How is the concentration of cholesterol in serum measured in this method?
How is the concentration of cholesterol in serum measured in this method?
Which component is not part of the enzymatic assay for cholesterol measurement?
Which component is not part of the enzymatic assay for cholesterol measurement?
What is the purpose of labeling test tubes as test (T), standard (S), and blank (B)?
What is the purpose of labeling test tubes as test (T), standard (S), and blank (B)?
What is the purpose of the cholesterol reagent in the experiment?
What is the purpose of the cholesterol reagent in the experiment?
What volume of monoreagent is added to each of the test tubes?
What volume of monoreagent is added to each of the test tubes?
At what temperature can the tubes be left to stand for the colorimetric measurement?
At what temperature can the tubes be left to stand for the colorimetric measurement?
What should be measured at a wavelength of 500 nm?
What should be measured at a wavelength of 500 nm?
What does the calculation for HDL Cholesterol involve?
What does the calculation for HDL Cholesterol involve?
Which component is not included in the blank tube during the experiment?
Which component is not included in the blank tube during the experiment?
What total cholesterol level is categorized as 'High'?
What total cholesterol level is categorized as 'High'?
Which LDL cholesterol level is considered 'Optimal'?
Which LDL cholesterol level is considered 'Optimal'?
What is the implication of an HDL cholesterol level less than 40 mg/dL?
What is the implication of an HDL cholesterol level less than 40 mg/dL?
When are direct LDL measures typically used?
When are direct LDL measures typically used?
How is VLDL typically estimated?
How is VLDL typically estimated?
What LDL cholesterol level is categorized as 'High'?
What LDL cholesterol level is categorized as 'High'?
What is the estimated VLDL error margin when triglycerides are above 400 mg/dL?
What is the estimated VLDL error margin when triglycerides are above 400 mg/dL?
Which total cholesterol level is categorized as 'Borderline high'?
Which total cholesterol level is categorized as 'Borderline high'?
Study Notes
Lipid Profile and Cholesterol Overview
- Lipid profile assesses levels of total cholesterol, HDL, triglycerides, and LDL.
- Cholesterol is a vital fatty substance present in every cell, contributing to hormone production and digestion.
- Around 70% of body cholesterol is synthesized in the liver while 30% comes from dietary sources (meat, eggs, dairy).
- High dietary fat intake can increase liver cholesterol production.
Types of Cholesterol
-
LDL (Low-Density Lipoprotein):
- Known as "bad" cholesterol; carries cholesterol from the liver to the bloodstream.
- Lower protein content with higher cholesterol levels, prone to sticking to blood vessel walls.
- High LDL levels are linked to atherosclerosis and heart disease, making its reduction a treatment target.
-
HDL (High-Density Lipoprotein):
- Considered "good" cholesterol, helps protect against heart disease.
- Higher levels are desirable; below 40 mg/dL is a major heart disease risk factor.
Normal Cholesterol Values
-
Total Cholesterol:
- Desirable: Less than 200 mg/dL.
- Borderline high: 200-239 mg/dL.
- High: 240 mg/dL and above.
-
LDL Cholesterol:
- Optimal: Less than 100 mg/dL.
- Near optimal: 100-129 mg/dL.
- High: 160-189 mg/dL.
- Very High: 190 mg/dL and above.
-
HDL Cholesterol:
- Protective: 60 mg/dL and higher.
- The higher, the better: 40-59 mg/dL.
- Major risk factor: Less than 40 mg/dL.
LDL Measurement and Calculation
- Total cholesterol is the sum of HDL, LDL, and VLDL.
- VLDL is estimated as one-fifth of triglycerides; Direct LDL measures are used for triglyceride levels over 400 mg/dL.
- Friedewald formula:
- Estimated LDL = Total cholesterol - (HDL + TG/5)
Estimation of Serum Cholesterol
- Method: Enzymatic colorimetric method.
- Principle: Cholesterol esterase hydrolyzes cholesterol esters into free cholesterol and fatty acids, followed by oxidation by cholesterol oxidase.
- The resultant hydrogen peroxide forms a red dye, which is quantitatively measured.
Steps for Cholesterol Estimation
- Utilize labeled test tubes for test, standard, and blank.
- Add reagents accordingly, incubate, then measure absorbance at 505 nm.
- Calculation formula:
- Cholesterol (mg/dL) = (A_sample / A_standard) x (standard concentration)
Estimation of HDL Cholesterol
- Method: Combination of separation and enzymatic colorimetric method.
- Principle: VLDL and LDL are precipitated with phosphotungstic acid/MgCl2, leaving HDL in the supernatant for analysis.
Steps for HDL Estimation
- Prepare test tubes for precipitation and colorimetric analysis.
- Incubate and centrifuge to obtain clear supernatant.
- Measure absorbance at 500 nm and calculate using:
- HDL Cholesterol (mg/dL) = (A_supernatant / A_standard) x (standard concentration)
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Description
This quiz focuses on Normal Values for Total Cholesterol Levels in Clinical Biochemistry. Students will evaluate different cholesterol categories based on specified thresholds. Ideal for second-stage medical laboratory technique students.
