Book 1: Biomedical Sciences Essential Laboratory Medicine

Question 1

What is clinical chemistry?

Answer 1

The area of pathology with soluble noncellular components analysis of body fluids.

Question 2

What is an example of a body fluid?

Answer 2

Blood.

Question 3

What can the soluble noncellular components be?

Answer 3

Small inorganic = salts, ions.
Large organic = lipids, steroids, drugs.
Macromolecules = albumin, enzymes, protein hormones.

Question 4

What is the aim of the biochemical tests used in a clinical chemistry laboratory?

Answer 4

To accurately quantify the soluble noncellular components of body fluid.

Question 5

What is it used in the laboratory to reduce variation of measurements?

Answer 5

Standard operating procedures (SOPs).

Quality control testing.

Question 6

What is examined in clinical chemistry?

Answer 6

Blood serum separately from blood plasma.

Urine.

Question 7

How is urine get collected for clinical analysis?

Answer 7

24h collection.

In a plastic container with an antibacterial agent from clinic.

Question 8

What is often collected as urine to be examined clinically?

Answer 8

Early morning urine (EMU).

Question 9

What are the benefits of collected early morning urine for analysis?

Answer 9

More concentrated.

Question 10

When is midstream urine (MSU) collected for analysis?

Answer 10

For microbiological purposes.

Question 11

How are blood samples collected for clinical analysis?

Answer 11

In tubes appropriate to the test required.

Question 12

What does blood serum contain?

Answer 12

Clotting factors.

Fibrinogen.

Question 13

Why is blood serum the optimal fluid for blood analysis?

Answer 13

The blood clots in a plain tube –> fibrinogen + clotting factors –> clot –> leave clot factor free –> yellow on top –> blood cells on bottom.

Question 14

What is the function of centrifugation?

Answer 14

It maximizes the volume of serum.

Question 15

What can a strong centrifugation cause to the sample?

Answer 15

Lysis of red cells –> release haemoglobin –> red contamination to serum.

Question 16

How can clotting be prevented?

Answer 16

By the presence of sodium citrate, heparin, EDTA in blood collecting tube.

Question 17

What is the function of anticoagulant?

Answer 17

It determines which which test can be performed.

Question 18

What is the function of Heparin?

Answer 18

It blocks clotting irreversibly.

Question 19

What is the function of EDTA?

Answer 19

Creates ions.
Adds excess of magnesium and calcium.
Enzyme analysis.

Question 20

What can clotting affect?

Answer 20

Blood glucose measurement.

Adrenaline/catecholamine measurement.

Question 21

How do hospital collect blood?

Answer 21

Via: Vacutainer tubes = Becton Dickinson (BD).

Question 22

What is the BD?

Answer 22

A plastic sleeve with a double-ended needle.

Question 23

How does the BD work to collect blood?

Answer 23

Screwing sleeve-covered-end of needle into holder –> puncturing holder’s vein with other end –> tube pushed down into holder –> blood drawn.

Question 24

What are creatinine measurements in humans based on analysis?

Answer 24

Constant = healthy humans.
Men = 9-18mmol/24h.
Women = 7-16mmol/24h.

Question 25

What is the biggest cause of error in clinical sample analysis?

Answer 25

Incorrect sample labelling.

Question 26

What must recorded in sample labelling?

Answer 26

Patient's full name. | Hospital reference numbers.

Question 27

What can mixing sample labels cause?

Answer 27

Inappropriate treatment. | Patient death.

Question 28

What can improve sample labelling?

Answer 28

Barcodes.

Question 29

What are some chemical analysis systems?

Answer 29

Light emission. Scattering absorption. Fluorescence. Luminescence.

Question 30

How does Flame photometry work as a clinical chemistry analyte?

Answer 30

A spectral scan of portion is produced when metals excite in flame --> lines of emission at wavelengths.

Question 31

What does the spectral emission produced by the flame photometry do?

Answer 31

It changes the colour of the source flame.

Question 32

For how many hours and degrees should NaCl and KC be dried before use?

Answer 32

2-3 hours. | 100 degrees.

Question 33

Where must chemicals be allowed to cool before weighing?

Answer 33

At room temperature. In desiccators. In container with tight-fitting lid with small air space.

Question 34

Why is the digital reading for Na adjusted to 140 and K to 50, after aspiration?

Answer 34

To represent them in undiluted serum.

Question 35

What is a classic example of a simple colorimetric assay in clinical chemistry?

Answer 35

Urea measurement.

Question 36

What happens in urea measurement?

Answer 36

Urea react with specific compounds --> colour product.

Question 37

What colour does urea give when it reacts with diacetyl mono-xime under strong acidic conditions?

Answer 37

Yellow.

Question 38

What happens to the colour produced by glucose colorimetry?

Answer 38

Removed.

Question 39

Why does the colour product from glucose colorimetry removed?

Answer 39

Colour reaction is a bystander effect of an introduced chromatophore reacting through enzyme. Metabolic product of glucose acts by a specific glucose degrading enzyme.

Question 40

What factor makes the yellow product from urea + diacetyl monoxime reaction into red?

Answer 40

Ferricions Thiosemicarbazide.

Question 41

With what does urea react in analysis by colorimetric assay, under strong acidic conditions?

Answer 41

With diacetyl monoxime.

Question 42

What does urea give when it reacts with diacetyl monoxime?

Answer 42

A yellow condensation product.

Question 43

By what is the reaction between urea and diacetyl monoxide boosted?

Answer 43

By ferric ions. | Thiosemicarbazide.

Question 44

What colour do ferric ions give to the urea reaction with diacetyl monoxime?

Answer 44

Intense red colour.

Question 45

For how long and in what temperature should we store samples?

Answer 45

No longer than 8 hours. At room temperature 25-35 degrees. and 7 days at 2-8 degrees.

Question 46

Where can we store the samples for longer than 8 hours?

Answer 46

In the freezer.

Question 47

What shall we do if the samples show evidence of bacterial contamination?

Answer 47

Do not use them for urea estimation.

Question 48

What else can be used to estimate urea?

Answer 48

Plasma.

Question 49

When is the colour reagent prepared?

Answer 49

Fresh at the time for analysis.

Question 50

How is the colour reagent prepared?

Answer 50

By mixing distilled water. Mixed acid reagent. Mixed colour reagent. In ration 1:1:1.

Question 51

How can we calculate the urea in test sample?

Answer 51

Urea in test sample = (Absorbance of test / Absorbance of Standard) * 150 mg/dl.

Question 52

What is urea in analytical methods?

Answer 52

One of the most common analytes measured in a laboratory.

Question 53

What is essential to involve in a urea analysis?

Answer 53

Normal QC pool = internal QC.

Question 54

What can be obtained from the QC results?

Answer 54

Mean. Standard deviation. %CV.

Question 55

What is the acceptable limit of urea analysis?

Answer 55

4%.

Question 56

What is the acceptable limit of %CV value of urea analysis?

Answer 56

8%.

Question 57

What is important for a company that uses QC to do?

Answer 57

Certify their QC materials are traceable to international reference materials.

Question 58

What are most of the chemicals used in a urea analysis?

Answer 58

Acids.

Question 59

What should we avoid doing during urea analysis?

Answer 59

Mouth pipetting. | Contact with skin.

Question 60

What happens in the Glucose analysis by colorimetric assay?

Answer 60

Glucose is presented in plasma --> oxidised by enzyme glucose oxidase (GOD). --> gluconic acid --> leaves hydrogen peroxide free.

Question 61

What happens to the free hydrogen peroxide?

Answer 61

Converted to water + oxygen, by enzyme peroxidase (POD).

Question 62

What else happens in the Glucose colorimetric assay?

Answer 62

4 amino phenazone takes oxygen --> + phenol --> pink coloured chromogen, at 515nm.

Question 63

What is the plasma in the Glucose colorimetric assay?

Answer 63

The specimen of choice for glucose estimation.

Question 64

For how many hours and at which temperature can plasma glucose levels be stable?

Answer 64

6 hours, at room temperature: 25-35 degrees.

Question 65

What is it important to happen in blood samples after collection?

Answer 65

Plasma should be separated from the cells.

Question 66

When should plasma be separated from the cells?

Answer 66

Within an hour after collection.

Question 67

How much patient's blood should be collected into an anticoagulant tube?

Answer 67

2 ml.