CC2 LAB MIDTERMS FLASHCARDS

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COVERAGE: LDH, AMYLASE, LIPASE

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73 Terms

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Tissue Source/s of LDH
Heart, liver, muscle, kidney
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Clinical Significance of LDH
↑ myocardial infarction, liver disease, renal disease, certain forms of anemia, malignant disease, progressive muscle dystrophy
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Clinical significance of amylase
Diagnosis of acute pancreatitis
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Clinical significance of lipase
Evaluate conditions associated with pancreas
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LDH equation
knowt flashcard image
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Amylase equation
knowt flashcard image
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Lipase equation
knowt flashcard image
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Reagent stability for LDH
Reconstituted: 14 days (ref temp) 8 hours (room temp)
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Reagent Composition LDH
• L-lactate (75mM)

• NAD (5.5 mM)

• Buffer (80 mM)

• pH 9.0

• Non-reactive stabilizers and fillers
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Specimen Stability LDH
Serum: 2-3 days at room temp
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Interfering Substances
oxalate

oxamate

EDTA
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LDH: Reagent Volume
1ml
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LDH: Pre-incubation (time and temp)
37°C for 3 minutes
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LDH: Sample Volume
25uL
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Wavelength LDH
340nm
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Multiplier of LDH
6592
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LDH: Time interval (reading)
2 minutes A1: read after 1 minute
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LDH: expected values
Males

50-166 IU/L (30°C)

80-285 IU/L (37°C)

Females

60-132 IU/L (30°C)

103-227 IU/L (37°C)
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formula for LDH
â–łAbs/min Ă— 6592
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Limitations (LDH)
Samples with values above 800 IU/L should be diluted 1:1 with saline, re-assayed and the results multiplied by two (2).
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Temperature Correction
1\. If the assay is performed at 37°C but is to be reported at 30°C; multiply the results by **0.6.**

2\. If the assay is performed at 30°C but is to be reported at 37°C; multiply the results by **1.7**
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LDH: procedure linearity
800 IU/L
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millimolar absorptivity of NADH
6\.22
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Formula to acquire multiplier in LDH
knowt flashcard image
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First quantitative method for Amylase assay
Iodemetric method
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Who introduced iodometric method?
Wohlegemuth
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Disadvantages of old methods in amylase assays
long incubation times

possible endogenous glucose interference
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Who introduced the current method/assay used to quantify amylase?
Wallenfels
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Substrate(s) in the method that Wallenfels introduced.
p-Nitrophenylglycosides or p-Nitrophenyl-D-Maltoheptaoside (PNPG7)
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Lipase hydrolyzes _____?
glycerol esters of long-chain fatty acids
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Advantage in the current method of amylase assay
short lag time

greater stability
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Final products of the reaction in amylase equation
p-Nitrophenol

Glucose
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What is measured in the LDH assay?
rate of formation of NADH
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What color is produced when PNPG1 is hydrolyzed by glucosidase to glucose and p-Nitrophenol?
yellow
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What are the three enzymes that are involved in the amylase assay?
amylase

glucoamylase

glucoasidase
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Wavelength (Amylase)
405nm
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Reagent stability (amylase)
Reconstituted:

10 days (room temp)

30 days (ref temp)

Unreconstituted:

until expiry (ref temp)
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Reagent Composition (Amylase)
• p-Nitrophenyl D-Malthoheptaoside 0.9 mM

• Glucosidase (yeast) (25, IU/L)

• Glucoamylase (Rhizopus Sp.) 10,000 IU/L

• Sodium chloride (50mM)

• Calcium chloride (5mM)

• Buffer (50mM)

• pH 6.9
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specimen for amylase assay
serum and urine
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Specimen Stability (amylase)
Serum & Urine:

1 week (room temp)

several months (ref temp)

\
Plasma: heparin tube

Urine: 24 hr period
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Interfering Substances
Macroamylasemia ↑ pancreatic amylase in serum

Lipemia and hemolysis ↑ amylase

Insulin and some bacteria ↑ amylase
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Reagent Volume (amylase)
1ml
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Pre-incubation (amylase)
37°C for 3 minutes
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amylase: specimen volume
25uL
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Multiplier (amylase)
4824
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Millimolar absorptivity of p-Nitrophenol
8\.5
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Time interval (reading)
Every 30 seconds for 2 minutes A1: read after 15 seconds

Note: 5 readings in total
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Expected Values Amylase
Serum: up to 96 IU/L Urine: 18 to 330 IU/L
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formula for amylase assay
â–łAbs/min Ă— 4824
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amylase procedure limitations
Samples that exceeded the linearity limit (1,500 IU/L) should be diluted with an equal volume of saline and rerun. Multiply the result by two
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To convert to nkat/L, the IU/L value should be multiplied to?
16\.67
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Formula for corrected ΔAbs. /5min
Corrected ΔAbs. /5min = ΔAbs test- ΔAbs blank
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why should hemolysis be avoided in LDH assay?
Erythrocytes release large amount of LDH (falsely elevated result)
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he modified the method introduced by Voget
Shibabi
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in the method proposed by Voget, what is measured in the assay?
rate of change in turbidity over a specific unit of time
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Serum lipase hydrolyzes ____?
olive oil emulsion
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TRUE OR FALSE. The increase in turbidity at 400nm is proportional to lipase activity in the specimen.
FALSE. (must be decrease in turbidity)
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Reagent composition (lipase)
• Substrate: olive oil in alcohol

• Buffer: tris buffer (69mM), sodium deoxycholate (10mM), pH 9.0
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Reagent stability (lipase)
Reconstituted: 7 days (refrigerated)

Unreconstituted: until expiry (room temp)
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In preparing the reagent for lipase assay, what volume of distilled water must be added?
25 ml
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Specimen stability (lipase)
Serum:

1 week (room temp)

3 weeks (ref temp)

several months (frozen)
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Interfering substance (lipase)
Hemolyzed specimen
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Reagent volume (lipase)
3 ml
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Pre-incubation
37°C for 5 minutes
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Sample volume (lipase)
100uL
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Wavelength (lipase)
400nm
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Multiplier (lipase)
1953
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concentration of olive oil (micromoles/liter) in the working solution
315
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Time interval (reading)
5 minutes after initial absorbance reading A1: read after adding sample and mixing (initial)
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Expected values (lipase)
Adults: 10-150 U/L (age more than 60 years old 18-180 IU/L)
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Procedure limitation (lipase)
Samples with values above 280 IU/L should be diluted 1:1 with distilled water, re-assayed and final results multiplied by two.
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To convert IU/L to Cherry-Crandall units, divide IU/L by
70
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One International Unit (IU) is defined as
the amount of enzyme that catalyzes the transformation of one micromole of substrate per minute under decreed conditions.