Clinical Chemistries: Intro to Clin Chem Flashcards

1
Q

What do Clinical Chemistries allow us to do?

A

Measure chemical components in the body that gives us information about the function of different organs

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2
Q

What type of sample do most chemical analyses require?

A

Serum

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3
Q

How long after collection do you need to analyze the sample?

A

1 hour

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4
Q

What should you do with the sample if you cannot analyze it within one hour?

A

Separate it and then refrigerate or freeze the sample

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5
Q

Good sample collection

A

Collect blood samples before treatment
The patient should be fasted
Use the largest vein possible
Use the proper syringe and needle size

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6
Q

Serum

A

Fluid portion of clotted blood
No fibrinogen
SST or RTT

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7
Q

Plasma

A

Fluid portion of whole blood
Has fibrinogen
GTT (heparin) or BTT

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8
Q

What is the advantage for using a green top tube?

A

You do not need to wait for the blood to clot before spinning for emergency/stat tests

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9
Q

What is the disadvantage for using a green top tube?

A

Only works as an anticoagulant for 8-12 hours

Can not use to send to lab

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10
Q

What happens to the serum during the clotting process?

A

The soluble fibrinogen in plasma is converted to an insoluble fibrin clot matrix

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11
Q

What happens to clotted blood when it is centrifuged?

A

The fluid is squeezed out and becomes serum

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12
Q

What happens when you centrifuge higher than 2000-3000 rpm for prolonged times?

A

Hemolysis may result

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13
Q

What is inside a serum separator tube?

A

Gel that forms a barrier between serum and blood cells

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14
Q

What do the inside walls of the serum separator have?

A

Silica particles that aid in clot activation

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15
Q

What do you do with the serum separator tube after blood has been collected?

A

Invert gently and let it sit for 20 minutes

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16
Q

Red top tube

A

No additives

Allow the clot to form by letting the blood sit for 20 minutes

17
Q

At what speed do you centrifuge the red top tube at and for how long

A

10 minutes

2000-3000 rpm

18
Q

What do you do with the serum after it is centrifuged?

A

Remove it with a pipette

Transfer it to another red top tube or white top tube

19
Q

What can falsely affect chemistry results?

A

Chemical contamination
Improper labeling and handling
Lipemia
Sample is left on the clot for too long before it was removed

20
Q

What causes hemolysis?

A

A damp syringe from auto-claving
Trauma to the RBCs
Sample is frozen or overheated
Too much alcohol on the skin

21
Q

How does hemolysis affect the sample?

A

It alters the makeup of serum or plasma

22
Q

How does hemolysis alter the makeup of serum or plasma?

A

The fluid from ruptured cells can dilute the sample
Can elevate potassium, phosphorus and enzymes
Can alter lipase and bilirubin values

23
Q

What fives things can you do to prevent hemolysis?

A

Mix the sample gently
Remove the needle from the syringe and transfer the blood directly into the tube
Good venipuncture technique with minimal trauma
Use large veins when possible
Never freeze whole blood

24
Q

What seven factors can influence the results of the clinical chemistries?

A
Chemical contamination (rare)
Improper labeling
Improper sample handling
Icterus
Fasting collections
Collecting immediately after a meal
Lipemia
25
How can improper labeling influence results?
Serious errors may occur Wrong results for the patient complete the request form correctly
26
How can improper sample handling influence results?
Analyze within one hour Keep at room temperature or freeze if over one hour Heat can destroy come chemicals and activate others
27
What happens if serum is left on the clot for too long
False decrease in glucose at a rate of 10% per hour by RBCs in vitro False change in electrolytes (phosphorus and potassium) and some liver enzymes (ALT, AST)
28
How can collecting blood immediately after a meal influence results?
The blood glucose will be elevated Inorganic phosphorus will be decreased Lipemia Kidney assay affected
29
How can Lipemia influence results?
High fat content in blood Milky appearance to serum Can cause errors with various chemistry tests
30
How long should a patient be fasted prior to sample collection?
8-12 hours
31
What are some causes of inaccurate results?
``` Poor-quality or outdated reagents Failure to calibrate or run controls Improper pipetting techniques Improper maintenance of instruments Lipemic or hemolyzed samples Allowing the serum to sit on the clot Improperly trained employees ```
32
What are the three types of errors?
Clerical Random Systematic
33
Clerical Errors
Mistakes in recording of data. sampling wrong patient, incorrect math calculations
34
Random Errors
Variations found in the lab including equipment failure, timing error
35
Systematic errors
Inaccurate standard control samples, reagent instability, handling errors, wrong method for a particular sample