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Clinical Chemistry Laboratory 2 > Serum Cholesterol > Flashcards

Flashcards in Serum Cholesterol Deck (19)
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0

Specimen

Serum
EDTA- plasma
Heparinized plasma

1

Optical path

1 cm

2

Reagent stability

Unopened - up to the expiry date (2-8 Celsius)
Opened - 6 weeks (2-8 Celsius)
Opened - 2 weeks (15-25 Celsius)

3

Recommended initial tests for evaluating blood cholesterol

Complete lipoprotein profile (TC, LDL-C, HDL-C, TAG)

4

Reaction principle

Cholesterol ester + water (CHE) ---> cholesterol + fatty acid
Cholesterol + oxygen (CHO) ---> cholestene-3-one + hydrogen peroxide
2 hydrogen peroxide + 4-aminoantipyrine + phenol (POD) ---> quinoneimine + 4 water

4

Formation of the indicator

Hydrogen peroxide and 4-aminoantipyrine in the presence of phenol and peroxidase

5

Preservative of reagents

Sodium azide (0.05%)

6

Values that do not influence serum cholesterol test

Hemoglobin values up to 200 mg/dL
Bilirubin values up to 5 mg/dL

7

Temperature

20-25 Celsius
37 Celsius

8

Indicator

Quinoneimine

10

Reagent composition

Phosphate buffer (pH 6.5)
4-aminoantipyrine
Phenol
Peroxidase
Cholesterolesterase
Cholesteroloxidase
Sodium azide

11

Linearity

Up to a cholesterol concentration of 750 mg/dL or 19.3 mmol/L

12

Calculation of the cholesterol concentration (mmol/L)

C = 5.17 x Absorbance (sample)/Absorbance (standard)

13

Wavelength

500 nm, Hg 546 nm

14

Incubation period

20 minutes at 20-25 Celsius
10 minutes at 37 Celsius

15

Blood cholesterol tests should be performed

in all adults aged 20 years and older, and should be repeated at least once every 5 years.

16

Clinical interpretation

Desirable = < 200 mg/dL
Borderline high = 200-239 mg/dL
High = >/= 240 mg/dL

17

Serum cholesterol is determined after

Enzymatic hydrolysis
Oxidation

18

Calculation of the cholesterol concentration (mg/dL)

C = 200 x Absorbance (sample)/Absorbance (standard)