chempathexam1

1. Multiple choices. Show working I explanation and give the correct answer.

1.1 In a spectrophotometric procedure that follows Beer's law, the absorbance of a standard solution of concentration 15 mmol/1 is 0.5 in a 1 em cell. The absorbance of the sample solution is 0.62. What is the concentration?
A. 0.62 mmolll
B. 6.2 mmol/1
C. 12.1 mmol/1
D. 18.6 mmol/1

1.2 How many grams of sulphosalicyclic acid (Mol weight 254g) are required to prepare 1 litre of a 3% solution?
A. 3.0
B. 7.6
c. 30
D. 254



1.3 How many grams of HzS04 are required to prepare 750 ml of a 2M solution?
A. 36.8
B. 73.5
c. 98
D. 147

• 1.4 A batch of test results is out- of- control . What should you do first?
A. Report the results to the physician first, then look for the trouble.
B. Follow the "out- of- control" procedure specified for the test method. C. Repeat the tests with a new lot of standards (calibrators)
D. Repeat the tests with a new lot of reagents.

1.5 How many grams ofNaOH are required to prepare 4 L of a 2M solution?
A. 40
B. 80
c. 160
D. 320

1.6 How many milliliters of concentrated HN03 (sp gr = 1.42 g/ml; assay= 70%) are required to prepare 21of a 0.15 M HN03?
A. 13.3
B. 19.0
c. 38.0
D. 189.0



1.7 An analysis for sodium is performed on an aliquot of a 24 hr urine specimen. A sodium value of 122.5 mmol/1 is read from the instrument. What is the amount of sodium in the 24 hour urine specimen if 1540 ml of urine are collected?
A. 79.5
B. 188.6
C. 1886.5
D. 18.8865

1.8 What is the relative centrifugal force (x g) of a centrifuge operating at 2500 rpm with a •
radius of 10cm? A. 625
B. 699
C. 1250
D. 6988

1.9 What amount ofNaCl is needed to obtain 50 mg Cl?
A. 19.6 mg B. 30.0mg C. 50.0 mg
D. 82.4mg

1.10 Which of the following is an effect of increased PTH secretion?
A. Decreased blood calcium levels
. B. Increased renal reabsorption of phosphate
C. Decreased bone resorption
D. Increased intestinal absorption of calcium

[10x2=20] .



Molecular mass:
H 1 S 32 016 Na 23 Cl 35.5 N 14

2.1 Calculate the amount of chemical you must weigh out to prepare the following: -


2.1.1
2.1.2
2.1.3 [Na23

150 ml of a 0.3 M sodium carbonate.
250 ml of sodium chloride; 500 mmol/1
750 ml of0.83% sodium chloride
C 12 0 16 Cl 35.45 ]




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2.2 In a new lab in eThekwini the QC officer decided to perform a recovery study for Iron using a new methodology. The sample preparations were as follows:
Sample 1: 5.0 ml serum+ 0.5 ml H20
Sample 2: 5.0 m1 serum+ 0.5 ml 75 J.lmoVI Fe Std
Sample 3: 5.0 ml serum+ 0.5 ml100 !lmoVI Fe Std

The concentrations were as follows:




Sample 1
Sample 2
Sample 3

Fe Measured
8 J.liDOI/1
12 J.lmol/1
15 J.lmol/1


2.2.1 Calculate the % recovery for sample 2 and sample 3. [15]


2.2.2 Giving reasons indicate which of the two samples perform better.

[2]



2.3 Discuss the concept of accreditation. [6]




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3.1 Betty is a 42 year- old overweight woman who presented with the complaint of cramps and 'spasms' of both hands. On examination she was found to be severely depressed and she further indicated that she had a thyroidectomy ten years prior. The pertinent biochemical findings were:




Plasma Creatinine Ca
ALP
Alb



85 !-!IDOl/]
1.28 mmol/1
65 U/L
39 g/1



3.1.1 Comment on the results and give possible diagnosis. Discuss all the possible reasons for such results. [6]

3.1.2 Name the various methods for calcium determination. Describe any principle (in detail)
that may be used for calcium determination in a Chern Path lab. [7]

3.1.3 Discuss the homeostasis of calcium. [10]

3.2 Lithium may be administered as lithium carbonate or lithium citrate and is used for the treatment on manic depression -manic depressive psychosis. Overdose may be life threatening.

3.2.1 Explain all the signs and symptoms of lithium toxicity. Indicate what happens after ingestion. [6]

3.2.2 Describe the methods used for lithium detection. [3]




4.1 In a Chemical Pathology laboratory, a CSF is considered a 'Stat' sample.

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4.1.1 Discuss the pathological variation of this fluid, with reference to the macroscopic appearance and colour. [7]

4.1.2 Give the reference range for CSF chloride and explain a case when abnormal.
Name methods used for CSF chloride measurement. [4]

4.2. Fluids are often received in major laboratories. Discuss four (4) of the following fluids:


4.2.1 Amniotic fluid
4.2.2 Sweat
4.2.3 Synovial fluid
4.2.4 Serous fluid
4.2.5 Pleural fluid

4.3 Provide an explanation I reasons for the following:

4.3 .1 A request form is a very important document and must be filled in accurately.








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4.3.2 Labs make booklets that are distributed to areas I sections where blood is taken.

4.3.3 Barcodes must be of good quality.



4.3.4 A hard copy of the results is usually kept in the laboratory.

4.3.5 When designing a lab, it is imperative to look at bench heights.

4.3.6 Tests that are expensive are usually grouped and run as a batch.

4.3.7 Messengers or couriers tend to delay delivery of specimens to the lab.

4.3.8 Qualified medical technologists verify results.

4.3.9 Chemical Pathology labs are mainly automated.


4.3 .10 Medical Technology staff are highly sought after.


[10]




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5.1 A 25 year old woman presented with a moderate painless goitre and difficulty in swallowing. She was anxious and has a noticeable tremor of her fingers. The doctor examined her and indicated that her neck was swelling, was diffuse and tender.

The thyroid results revealed:

rT4 45 nrnol/1

TSH 0.01 miU/1

Antibodies to the thyroid gland were done and came back negative.

5.1.1 Judging from the results, give the clinical picture of the patient. [6]

5.1.2 Discuss the evaluation of thyroid function and some of the typical signs for the above condition. [12]

5.2 Differentiate between the various types of hypothyroidism, explaining the tests used for its diagnosis.
[7]

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6. Recently doctors are increasingly attending to patients who are suspected of taking drugs.

6.1. Describe the rationale that is used for requesting a serum drug assay. [10]



6.2 Discuss the 5 classification of drugs that are frequently encounted in overdose situations. [10]



6.3 There are several factors that influence toxicology. Describe these where if untreated it may be fatal. [6]



6.4 Briefly outline the effects of ingestion of salicylates (aspirin) in overdose cases.
[7]




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