Biochemistry

Question 1

Accuracy

Answer 1

How close the result is to the actual ‘true’ value

Question 2

Precision

Answer 2

Reproducibility of an analytical result

Question 3

Reference interval

Answer 3

Typically, the middle 95% of the population shown on the biochemistry graph generate the reference interval. The 2.5% of the population on either side shows an ‘abnormal’ result

Question 4

Sensitivity

Answer 4

Tells you how good a test is at identifying disease

Question 5

Specificity

Answer 5

Measure of how good the test is at identifying health

Question 6

Positive predictive value

Answer 6

The percentage of people with a positive test who have the disease

Question 7

Negative predictive value

Answer 7

The percentage of people with a negative test who don’t have the disease

Question 8

Some contributors to pre-analytical variation

Answer 8

Time of day, posture, fasting status, recent exercise, time in transit to laboratory, temperature during transit, anticoagulant or preservative used

Question 9

The respiratory component and the metabolic component

Answer 9

pCO2 = respiratory component
HCO3- = metabolic component

Question 10

Acidaemia and alkalaemia

Answer 10

Acidaemia = ↑[H+]
Alkalaemia = ↓[H+]

Question 11

Acidosis and alkalosis

Answer 11

Acidosis = ↑[H+] or a process tending to cause ↑[H+]
Alkalosis = ↓[H+] or a process tending to cause ↓[H+]

Question 12

Respiratory acidosis

Answer 12

↑[H+] due to ↑pCO2

Question 13

Respiratory alkalosis

Answer 13

↓[H+] due to ↓pCO2

Question 14

Metabolic acidosis

Answer 14

↑[H+] due to ↓HCO3-

Question 15

Metabolic alkalosis

Answer 15

↓[H+] due to ↑HCO3-

Question 16

Respiratory vs Metabolic compensation

Answer 16

Respiratory - too much [H+] results in the lungs blowing off CO2
Metabolic - too much CO2 results in the kidneys getting rid of [H+]

Question 17

Some causes of respiratory acidosis

Answer 17

Choking, bronchopneumonia, chronic obstructive airway disease

Question 18

Some causes of respiratory alkalosis

Answer 18

Hysterical over-breathing, mechanical over-ventilation, raised intracranial pressure

Question 19

Some causes of metabolic acidosis

Answer 19

Impaired H+ secretion, increased H+ production or ingestion, loss of HCO3-

Question 20

Some causes of metabolic alkalosis

Answer 20

Loss of H+ in vomit, alkali ingestion, potassium deficiency