Clinical Chemistry

Question 1

what is the purpose of an emergency laboratory?

Answer 1

provide facilities for urgent tests, the results of which are likely to result in immediate clinical action

Question 2

what needs to be documented on a sample? (10)

Answer 2

1. age
2. sex
3. pregnant?
4. stage of menstrual cycle
5. body size
6. ethnic group
7. genetic variant
8. non-specific illness
9. medication
10. normal diet/exercise?

Question 3

1. what is blood collected in?
2. what is plasma?
3. what is serum?

Answer 3

1. vials with coagulation factors
2. blood with all cells removed
3. blood with cells and coagulation factors removed

Question 4

what is the purpose of:

1. one off tests
2. biochemical profiles
3. dynamic function tests

Answer 4

1. designed to answer specific questions, the answer to which will support diagnosis (i.e. does the patient have raised urea concentration?)

2, provide useful information on the disease status by analysing multiple constituents

3. designed to measure the body’s response to an external stimulus

Question 5

PKU

1. which enzyme regulates the amount of phenylalanine in the blood and how?
2. What substance is present on the agar plate of the PKU test. What is the role of this?
3. what happens in a positive result?
4. what happens in a negative result?

Answer 5

1. phenylalanine hydroxylase. Converts phenylalanine to tyrosine
2. beta2-tienylalanine. Inhibits bacterial phenylalanine hydroxylase
3. functional phenylalanine hydroxylase from the sample is able to rescue activity of inhibited bacterial enzyme - bacterial growth
4. no growth as there is no functional phenylalanine hydroxylase in the sample to rescue the inhibited bacterial enzyme - no bacterial growth

Question 6

1. define sensitivity

2. define specificity

Answer 6

1. how good a test is at detecting those with disease

2. how good a test is at discriminating against disease and no disease

Question 7

Name 6 liver function tests and what they indicate

Answer 7

1. Bilirubin - increases indicate blockages in the bile duct
2. aminotransferases - non specific markers of general liver disease
3. alkaline phosphatase - decreased in liver disease but increased in response to cholestasis
4. gamma-glutamyl transpeptidase - activity raised in cholestasis
5. plasma proteins - low levels indicative of liver disease
6. prothrombin time - increased time is an early indication of liver disease