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Questions and Answers
The kit compounds are stable until one year after the expiry date stated on the label.
The kit compounds are stable until one year after the expiry date stated on the label.
False (B)
The cholesterol standard concentration is 100 mg/dL.
The cholesterol standard concentration is 100 mg/dL.
False (B)
Cholesterol exists in the human blood only as a free sterol.
Cholesterol exists in the human blood only as a free sterol.
False (B)
Store the kit at room temperature.
Store the kit at room temperature.
The imbalance in the level of lipoproteins in plasma leads to hyperlipoproteinemias, a group of disorders that affects protein levels in serum.
The imbalance in the level of lipoproteins in plasma leads to hyperlipoproteinemias, a group of disorders that affects protein levels in serum.
The cholesterol in serum or plasma is stable up to 1 day at 2-8°C.
The cholesterol in serum or plasma is stable up to 1 day at 2-8°C.
Jaundice of the obstructive type usually is accompanied by a normal total serum cholesterol with a normal ester fraction.
Jaundice of the obstructive type usually is accompanied by a normal total serum cholesterol with a normal ester fraction.
Add 1 ml of serum to the sample tube.
Add 1 ml of serum to the sample tube.
The method for the measurement of total cholesterol in serum involves the use of two enzymes.
The method for the measurement of total cholesterol in serum involves the use of two enzymes.
The color is stable for 1 hour protected from light.
The color is stable for 1 hour protected from light.
Samples with concentrations higher than 400 mg/dl should be diluted 1:2 with saline and assayed again.
Samples with concentrations higher than 400 mg/dl should be diluted 1:2 with saline and assayed again.
Cholesterol esterase (CE) converts cholesterol into cholestenone and H2O2.
Cholesterol esterase (CE) converts cholesterol into cholestenone and H2O2.
The quinoneimine dye is proportional to the concentration of fatty acids in the sample.
The quinoneimine dye is proportional to the concentration of fatty acids in the sample.
Multiply the results by 5 if the sample concentration is higher than 600 mg/dl.
Multiply the results by 5 if the sample concentration is higher than 600 mg/dl.
Reagent 1 is prepared by a non-linear method.
Reagent 1 is prepared by a non-linear method.
All of the reagents are prepared by a different company as a kit.
All of the reagents are prepared by a different company as a kit.
Study Notes
Cholesterol Determination
- Cholesterol exists in the human blood as a free sterol and in an esterified form.
- The knowledge of plasma levels of lipids (cholesterol and triglycerides) together with lipoproteins of high and low density (HDL and LDL) aids in the detection of metabolic disorders of high risk.
- Imbalance in lipoprotein levels in plasma leads to hyperlipoproteinemias, a group of disorders that affect lipid levels in serum, causing coronary heart disease (CHD) and atherosclerosis.
Clinical Importance
- Elevated total serum cholesterol with a normal ester fraction is usually accompanied by obstructive jaundice.
- Diabetes, hypothyroidism, and certain types of kidney disease may exhibit the same cholesterol disturbance.
- Low total cholesterol values with normal ester fractions are noted mainly in hyperthyroidism and malnutrition.
Principle of Measurement
- The method involves the use of three enzymes: cholesterol esterase (CE), cholesterol oxidase (CO), and peroxidase (POD).
- The enzymes convert cholesterol into a quinoneimine dye proportional to the concentration of cholesterol in the sample.
Reagents Preparation
- All reagents are prepared by linear S.L.U. Company as a kit.
- Reagent 1 (Monoreagent) contains: PIPES, sodium cholate, cholesterol esterase, cholesterol oxidase, peroxidase, 4-aminoantipyrine, phenol, and non-ionic tensioactives.
- Reagent 2 (Cholesterol standard) contains: cholesterol 200 mg/dL (5.18 mmol/L).
Samples and Storage
- Serum, EDTA or heparinized plasma free of hemolysis are suitable samples.
- Cholesterol in serum or plasma is stable up to 5 days at 2-8°C and for a few months at –20°C.
- Reagents should be stored at 2-8°C, protected from light, and prevented from contamination.
Procedure
- Bring reagents and samples to room temperature.
- Mix 1 ml of monoreagent with 10 µl of serum or standard solution, and incubate for 10 minutes at room temperature or 5 minutes at 37°C.
- Read the absorbance (A) of the samples and the standard at 500 nm against the reagent blank.
- Calculate the cholesterol concentration using the equation: A sample / A standard x C standard.
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Description
Test your knowledge on the clinical importance of cholesterol levels in blood, including its forms, lipoproteins, and related metabolic disorders. Learn how to detect conditions like hyperlipoproteinemias and more.
