Biochemisty

Question 1

1. Which one of the following is an enzyme that is considered the most tissue-specific?
   a) Creatine kinase (CK)
   b) Alcohol dehydrogenase
   c) Amylase
   d) Alkaline phosphatase (ALP)
   e) Topoisomerase

Answer 1

b) Alcohol dehydrogenase

Question 2

Which of the following is a definition of clinical audit?
a) Everything that the laboratory does to assure a high-quality service to its users
b) Monitoring by professional accrediting organizations
c) Ensuring results are reproducible
d) Analysis of materials with known concentrations of specific substances to ensure, in real-time, that they are producing reliable results
e) A quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change

Answer 2

quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change

Question 3

Which one of the following abnormal conditions can be tested by monitoring prealbumin levels?
a) Prostate cancer
b) Malnutrition
c) Appendicitis
d) Fungal infection
e) Skin cancer

Answer 3

Malnutrition

Question 4

Which one of the following is true for albumin?
a) The most abundant protein in blood plasma
b) Gives blood its red color
c) Is a very large protein with a mass of over 100 kDa in size
d) Is absent from blood plasma except in some disease conditions
e) Cannot be assayed by normal dye binding assays

Answer 4

The most abundant protein in blood plasma

Question 5

Which one of the following does NOT normally cause low albumin levels in the plasma?
a) Liver disease
b) A protein-losing enteropathy such as seen in Crohn’s disease
c) Severe inflammation or shock
d) Dehydration
e) Malabsorption of protein

Answer 5

Dehydration

Question 6

Which one of the following is an enzyme that is considered the most tissue-specific?
a) Creatine kinase (CK)
b) Amylase
c) Alkaline phosphatase (ALP)
d) Alcohol dehydrogenase
e) Topoisomerase

Answer 6

Alcohol dehydrogenase

Question 7

Which is found in obstructive jaundice?
a) High serum unconjugated bilirubin
b) High serum conjugated bilirubin
c) Dark stools due to increased bilirubin metabolites
d) Increased serum haptoglobin
e) Low serum unconjugated bilirubin

Answer 7

b) High serum conjugated bilirubin

Question 8

Which of the following is NOT a function of the kidney?
a) Regulate blood pressure
b) Regulate fluid balance
c) Regulate acid-base balance
d) Production of vitamin B complex
e) Excretion of waste products

Answer 8

Production of vitamin B complex

Question 9

Which of the following does NOT increase the glomerular filtration rate (GFR)?
a) Decreased albumin concentration in the plasma
b) Vasodilation of the afferent (pre-glomerular) arteriole
c) Vasoconstriction of the efferent (post-glomerular) arteriole
d) Alcohol consumption
e) Hypovolemia (low blood volume)

Answer 9

Hypovolemia (low blood volume)

Question 10

Which of the following electrolyte changes are commonly associated with chronic renal failure?
a) Low sodium, low potassium
b) High sodium, high potassium
c) Low sodium, high potassium
d) High sodium, low potassium
e) Low sodium, high calcium

Answer 10

Low sodium, high potassium

Question 11

Which lipoprotein carrier is the predominant carrier of cholesterol in plasma in humans?
a) LDL
b) HDL
c) VLDL
d) IDL
e) Albumin

Answer 11

LDL

Question 12

Which of the following could NOT lead to low cholesterol levels?
a) Malabsorption
b) Statin treatment
c) Liver disease/cirrhosis
d) Nephrotic syndrome
e) Chronic parenchymal disease

Answer 12

Nephrotic syndrome

Question 13

Which of the following is true of type I diabetes mellitus?
a) Is the least common form of the disease
b) Is mostly diagnosed in juveniles, age 9 to 14
c) Is mostly diagnosed in those over the age of 40 years
d) Has an absolute requirement for insulin replacement to preserve life
e) Is not associated with obesity

Answer 13

Is mostly diagnosed in those over the age of 40 years

Question 14

Which of the following does NOT produce hyperglycemia?
a) Decreased insulin secretion
b) Increased carbohydrate intake
c) Decreased peripheral glucose uptake
d) Increased ketogenesis
e) Increased hepatic glucose output

Answer 14

Increased ketogenesis

Question 15

What percentage of people with diabetes have type 2 diabetes?
a) 10%
b) 5% to 10%
c) 25%
d) 50%
e) 90% to 95%

Answer 15

e) 90% to 95%

Question 16

Serum from a man who has dermatomyositis had LDH isoenzymes analyzed using thin-layer agarose gel electrophoresis. Which isoenzyme would be expected to have the highest peak?
a) LD1
b) LD2
c) LD3
d) LD4
e) LD5

Answer 16

LD5

Question 17

A 62-year-old man presented to his GP with a painful, red big toe. Blood testing showed:
Serum urate 0.74 mmol/L (0.23-0.46). What would be the most useful additional biochemistry test to perform in this situation?
a) Cholesterol
b) Creatinine
c) Glucose
d) Lactate
e) LDH

Answer 17

Creatinine

Question 18

A 57-year-old woman gave a history of recent weight loss with weakness and limb pain, which had worsened progressively over the past two years. Results showed:
Calcium 2.25 mmol/L
Phosphate 0.48 mmol/L
ALP 379 U/L
A diagnosis of tumor-induced osteomalacia was suspected. Which laboratory test is most likely to confirm the diagnosis?
a) ALP isoenzymes
b) 1,25-dihydroxyvitamin D
c) FGF-23
d) PTH-RP
e) TMP/GFR

Answer 18

FGF-23

Question 19

A 3-year-old boy was investigated for short stature. Results showed:
Sodium: 137 mmol/L
Potassium: 4.5 mmol/L
Creatinine: 28 μmol/L (23-37)
Adjusted calcium: 2.25 mmol/L
Albumin: 38 g/L
ALP: 19 U/L (60-425)
Phosphate: 1.0 mmol/L
TSH: 2.7 mU/L
25-OH vitamin D: 35 nmol/L
Zinc: 3.2 μmol/L (6-25)
What is the most likely cause of the low ALP?
a) EDTA contamination
b) Hypophosphatasia
c) Magnesium deficiency
d) Vitamin D deficiency
e) Zinc deficiency

Answer 19

Zinc deficiency

Question 20

Various parameters can be calculated to assess the biochemical test performance in different clinical circumstances. In screening, how is the diagnostic specificity of a test defined?
a) Affected individuals identified, divided by the total of positive results
b) Affected individuals identified, divided by the total of those with the condition
c) Correct results, divided by the total number of subjects studied
d) Healthy individuals identified, divided by the total number unaffected
e) Healthy individuals identified, divided by the total number of normal results

Answer 20

d) Healthy individuals identified, divided by the total number unaffected

Question 21

What is the best explanation for the following set of results?
Myoglobin: 13,190 ng/mL (normal 0-60)
CK-MB: 68.1 ng/mL (normal 0-5.0)
cTnT: 0.02 ng/mL (normal 0-0.1)
a) Acute myocardial infarction (AMI) within 6 hours after onset
b) Chronic renal failure
c) AMI 96 hours after onset
d) Acute rhabdomyolysis
e) Acute renal failure

Answer 21

Acute myocardial infarction (AMI) within 6 hours after onset