Lab Flashcards
What method was used in the lab to measure total protein?
Biuret method
What does the biuret method consist of?
Copper sulfate reacting with peptide bonds with increasing intensity to their concentration. Colored chelate forms with amine nitrogen of the peptide bond with an absorbance at 540nm.
What type of amino acids react with the biuret method?
Tripeptides and polypeptides. Dipeptides or single amino acids do not.
What is intensity of color in biuret method results proportional to?
Number of peptide bonds and therefore protein concentration
Identify the other methods for assessing total protein.
Kjehldahl
Refractometry
UV absorption
What method is used for detecting albumin?
Dye binding technique
How does the dye binding technique work?
In dye binding technique, anionic dye binds to albumin at a pH of 4.2, pH at which albumin is cationic. BCG binds specifically to albumin although it will bind other plasma proteins over time. BCG binds to protonated amine groups on the albumin molecule and the complex forms a color at 550-630 nm
What type of specimens are used for total protein albumin measurements?
Serum
Heparinized plasma
Body fluids/urine
What is the reference interval for total protein?
6.5-8.3 g/dL
What is the reference interval for albumin?
3.5-5.5 g/dL
What is automation?
The mechanization of chemical analyses done in order to minimize manual manipulation
List the steps in the automated process
Separation/mixing Sample/reagent handling Incubation Reaction and reaction analysis Derivation/interpretation of results Result reporting
What are the advantages of automation?
Time saving
Removes human performance variability
Reduces error
Saves money
What are the disadvantages of automation?
High initial/startup cost
Discontinued or updated products and reagents
Special training required
What are discrete analyzers?
Analyzers in which samples and reagents are mixed and react in individual cucette or slide
What are continuous flow analyzers?
Analyzers in which sample is injected into a reagent stream and reactions take place in tubing
What can be a major problem with continuous flow analyzers?
Carryover
How does sample processing with batch analyzers work?
Only one analysis is performed on a single specimen at a time or many specimens are sequentially moved through the analyzer as one batch
How does random access analyzers work?
Operators can program a number of tests, profiles/panels, QC on any given specimen in any order. Many analyses can be performed on a single specimen before moving on to the next sample
What is the most common system of analyzers?
Random access analyzers
What are calibrators or standards?
These are substances of known concentration run initially to create a standard curve
How many cakibartions are there?
One calibration per analyte
What are unknowns comapred to?
Standards on the curve once validated through calibration and QC
What are controls?
Substances of a known general range run daily or per shift to confirm system validity through QC
What us a substance with a specific known concentration?
Standard/calibrator
What is a substance similar to patient samples that has a known set of ranges? Usually pooled serum or plasma
Control
What substance tests an instrument to ensure that accuracy and precision of the equipment in order to validate the reliability of the system?
Control
What substance is used to setup an instrument, setting up a measuring scale to compare unknowns to
Calibrator/standard
How often are standards run?
Occasionally like after a new instrument install
On how many levels are standards run?
They’re run on multiple levels to get a multipoint calibration
Hi
How often are controls run?
They’re ran as a patient is tested everyday or per shift.
On how many levels are controls run?
Run on multiple levels to test both normal and abnormal range reliability.
When 3 levels: low abnormal, normal, high abnormal
When 2 levels: normal and abnormal
What is sensitivity?
It is the ability of an instrument to detect the smallest amount of an analyte
Describe the relationship between sensitivity and concentration
The more sensitive a test is, the lower the concentration it can detect
What is accuracy?
It is the capability of an instrument to provide a true of a quantity
What is precision?
Precision is a measure of the reproducibility of an instrument. Do repeated measures give the same value no matter the accuracy?
Define linearity
It is the ability of an instrument to give a constant ratio of a response to varying concentrations of stimulus when they are in direct proportion
What is the purpose of linearity?
Checks out that the output reading of an instrument is linearly proportional to the quantity being measured
Defines the range of the method within which the results are obtained accurately and precisely
what are chemistry panels/profiles?
Variety of tests designed to assess a single system (renal, hepatic, pancreatic) or state (metabolic, lipid)
How is LDC calculated?
LDL = Total CHOL - HDL - TG/5
