Clinical Chemistries: Intro to Clin Chem

Question 1

What do Clinical Chemistries allow us to do?

Answer 1

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

Question 2

What type of sample do most chemical analyses require?

Answer 2

Serum

Question 3

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

Answer 3

1 hour

Question 4

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

Answer 4

Separate it and then refrigerate or freeze the sample

Question 5

Good sample collection

Answer 5

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

Question 6

Serum

Answer 6

Fluid portion of clotted blood
No fibrinogen
SST or RTT

Question 7

Plasma

Answer 7

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

Question 8

What is the advantage for using a green top tube?

Answer 8

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

Question 9

What is the disadvantage for using a green top tube?

Answer 9

Only works as an anticoagulant for 8-12 hours

Can not use to send to lab

Question 10

What happens to the serum during the clotting process?

Answer 10

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

Question 11

What happens to clotted blood when it is centrifuged?

Answer 11

The fluid is squeezed out and becomes serum

Question 12

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

Answer 12

Hemolysis may result

Question 13

What is inside a serum separator tube?

Answer 13

Gel that forms a barrier between serum and blood cells

Question 14

What do the inside walls of the serum separator have?

Answer 14

Silica particles that aid in clot activation

Question 15

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

Answer 15

Invert gently and let it sit for 20 minutes

Question 16

Red top tube

Answer 16

No additives

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

Question 17

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

Answer 17

10 minutes

2000-3000 rpm

Question 18

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

Answer 18

Remove it with a pipette

Transfer it to another red top tube or white top tube

Question 19

What can falsely affect chemistry results?

Answer 19

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

Question 20

What causes hemolysis?

Answer 20

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

Question 21

How does hemolysis affect the sample?

Answer 21

It alters the makeup of serum or plasma

Question 22

How does hemolysis alter the makeup of serum or plasma?

Answer 22

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

Question 23

What fives things can you do to prevent hemolysis?

Answer 23

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

Question 24

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

Answer 24

Chemical contamination (rare)
Improper labeling
Improper sample handling
Icterus
Fasting collections
Collecting immediately after a meal
Lipemia

Question 25

How can improper labeling influence results?

Answer 25

Serious errors may occur
Wrong results for the patient
complete the request form correctly

Question 26

How can improper sample handling influence results?

Answer 26

Analyze within one hour
Keep at room temperature or freeze if over one hour
Heat can destroy come chemicals and activate others

Question 27

What happens if serum is left on the clot for too long

Answer 27

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)

Question 28

How can collecting blood immediately after a meal influence results?

Answer 28

The blood glucose will be elevated
Inorganic phosphorus will be decreased
Lipemia
Kidney assay affected

Question 29

How can Lipemia influence results?

Answer 29

High fat content in blood
Milky appearance to serum
Can cause errors with various chemistry tests

Question 30

How long should a patient be fasted prior to sample collection?

Answer 30

8-12 hours

Question 31

What are some causes of inaccurate results?

Answer 31

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

Question 32

What are the three types of errors?

Answer 32

Clerical
Random
Systematic

Question 33

Clerical Errors

Answer 33

Mistakes in recording of data. sampling wrong patient, incorrect math calculations

Question 34

Random Errors

Answer 34

Variations found in the lab including equipment failure, timing error

Question 35

Systematic errors

Answer 35

Inaccurate standard control samples, reagent instability, handling errors, wrong method for a particular sample