Chempath test 3

1. Multiple choice: Choose the correct answer; showing how you obtained your answer
1.1 What is the molarity of a solution that contains 18.7g of KCl in 500 ml?
0.1
0.5
1.0
5.0

1.2 How much 95% alcohol is required to prepare 5 L 70% alcohol?
A. 2.4 L
B 3.5 L
3.7 L
4.4 L

How many milliliters of concentrated H2SO4 (100%) are required to prepare 10L of 0.1 M H2SO4?
A. 1.84
9.20
27.5
54.9

In a spectrophotometric procedure that follows Beer’s law, the absorbance of a standard solution of concentration 15 g/L is 0.50 in a 1 cm cell. The absorbance of the sample solution is 0.62. What is the concentration?
0.62 g/L
6.2 mol/L
12.1 g/L
18.6 g/L

1.5 How many grams of Na0H are required to prepare 2500 mL of a 4 M solution?
40
100
160
400

1.6 An isotonic saline solution contains 0.85% NaCl. How many grams of
NaCl are needed to 5 L of this solution?
4.25
8.5
42.5
170

How many milliliters of concentrated HN03 are required to prepare 2 L of 0.15 N HN03?
13.3
19.0
38.0
189.9

An analysis for sodium is performed on an aliquot of a 24- hour urine specimen. A sodium value of 122.5 mmol/l is read from the instrument. What is the amount of sodium in the 24hr urine specimen if 1540 mL of urine are collected?
79.5
188.6
1886.5
18,865
8 x 2 = 16
Additional information: Molar mass:
K 39 Cl 35.5 H 1 S 32 O 16 N 14 Na 23 C 12


2. Grace, a 49 year-old woman was admitted to the Inkosi Albert Luthuli Central Hospital for cataract extraction. Her eyesight was deteriorating but otherwise she was in good health. In 1990 Grace had undergone thyroidectomy for a multinodular goiter. Routine investigations were carried out using a blood sample from the patient.

Tests
Serum
Calcium 1.66 mmol/l
Phosphate 2.65 mmo/l
Albumin 42 g/l
Alkaline phosphatase 65 IU/L

2.1 Comment on the results. [6]
2.2 What was the main clue for the diagnosis apart from the patient’s results? [1]


3. After a phosphorous analysis using the molybdate method without a reducing agent, the following absorbance readings were obtained:-

Standard (1.6 mmol/l) 0.414
Standard 0.418
Normal control 0.380
Serum A 0.678
Serum B 0.350
Urine sample C (diluted 1 in 5) 0.204
(Volume 1567)

Calculate the phosphorus concentration for all specimens/controls.
If the mean target value for the normal control is 1.41 mmol/l and the SD is 0.10; is your batch of results within acceptable limits?
Which of the two serum samples gives an abnormal result? Can you give a possible cause for it?
Describe the principle of the method used.
Discuss all the precautions that must be taken when a serum sample is taken for phosphate determination. [20]
4. A 50-year-old man presented with weight loss and weakness. The time of the year was winter but his skin was noticeably bronzed. On examination, he was found to have hepatosplenomegaly.

Investigations
Urine positive for glucose
Blood sugar 12 mmol/l

Serum
Iron 58 µmol/l
Transferrin 2.15 g/l
Ferritin 3500 µg/ml

4.1 Predict the diagnosis of the patient. Justify your answer with explanations and show calculations. [8]


5. Provide an explanation / reasons for the following:

Tumor markers are processed in a batch.
Two – way traffic of samples and reports.
Receptions area should be free of clutter.
Bulk of the work is done in the first shift.
Transcription mistakes are not allowed.

[10]

6. Complete the following table.
Laboratory markers of iron status in Disease States

Conditions Serum Iron Transferrin Ferritin % Saturation

Malnutrition   6.1 Variable
Malignancy   6.2 
Chronic infection 6.3   
Viral hepatitis    6.4
Anaemia of chronic disease  6.5 Normal/  
Sideroblastic anaemia  Normal / 6.6 
Iron deficiency 6.7   6.8
Iron poisoning / overdose  6.9  
Haematochromatosis    6.10

[10]


7. Make recommendations of how space could be best utilized when designing a laboratory.
[4]