Chemical Pathology 17 - EMQs on Enzymes, Chemistry

Question 1

What type of technetium is used in bone scans vs thyroid scans?

Answer 1

Bone scans: Tc bisphosphonate (radioactively labelled bisphosphante)
Thyroid scans: Tc pertechnate

Question 2

Which type of nuclear medicine test is most useful for identifying Ca cells themselves?

Answer 2

FDG-PET

**shows metabolic activity of cancer cells**

Question 3

Which type of nuclear medicine test is most useful for identifying primary neuroendocrine tumours (eg insulinomas)?

Answer 3

Gallium 68 dotatate PET and CT (identifies somatostatin receptor)

**this is not FDG PET**

Question 4

Which type of nuclear medicine test is most useful for parathyroid scans?

Answer 4

Sesta MIBI scan

Question 5

Which type of nuclear medicine test is most useful for investigating for a phaeochromocytoma?

Answer 5

MIBG (looks for phaeo mets)

Question 6

Recall the timeline of elevation of troponin I, AST and LDH elevation post-MI

Answer 6

Troponin I - first few hours
AST - first day
LDH - over first 5 days

Question 7

Which LFT result will be most deranged in obstructive jaundice?

Answer 7

ALP

Question 8

Descrine the pathophysiology of alcoholic hepatitis causing portal hypertension

Answer 8

Alcoholic hepatitis –> hepatocyte death
The person becomes ill and recovers, and the hepatocytes regenerate. However, rather than regenerating as before, they form a NODULE
This nodule disrupts hepatic micro-architecture between the portal vein and the central vein
If enough nodules appear, this increases pressure in the portal vein –> portal HTN

Question 9

Which enzymes are most elevated by gallstones vs viral hepatitis and why?

Answer 9

Gallstones: ALP - stones tend to cause most damage near portal triad, where more ALP is made

Viral hepatitis - ALT - the virus tends to affect hepatocytes around the central vein the most, where ALT is predominantly produced

Question 10

What marker is raised in paget’s disease of the bone?

Answer 10

ALP

Question 11

What marker is raised in osteomalacia?

Answer 11

ALP

Question 12

Which of these is raised after acute MI?

Answer 12

AST

Question 13

Which enzymes increase after an MI?

Answer 13

1. troponins - msot sensitive, rises within 6 hours
2. CKMB
3. AST- over a day
4. LDH- over 5 days

Question 14

What is another name for prostate specific antigen?

Answer 14

acid phosphatase

Question 15

What is ALP in priimary hyperparathyroidism?

Answer 15

Tends to be normal

Question 16

What is Vitamin D like in primary hyperparathyoridism?

Answer 16

LOW

High PTH–> consumes inactivated Vitamin D (this is what is measured in the blood rather than activated vitamin D)

Question 17

Between urea and creatinine which one goes up first rapidly in acute renal failure?

what about chronic renal failure?

Answer 17

urea

creatinine (c for chronic, c for creatinine)

Question 19

What is a marker of glucose control over the last 3 weeks?

Answer 19

FRUCTOSAMINE

Question 21

What is the histology of a brown’s tumour?

Answer 21

giant multinucleate cells

Question 22

what does this chest x ray show?

Answer 22

bilateral hilar lmphadenopathy

Question 23

how does sarcoidosis cause hypercalcaemia?

Answer 23

sarcoid tissue (macrophages) expresses ectopic 1 alpha hydroxylase

this produces activated vitamin D

which increases calcium absorption

this suppresses PTH

**gives you seasonal hypercalcaemia - only in the summer where you have enough sunlight**

Question 24

What produces ALP?

Answer 24

osteoblasts

Question 25

What test is used to diagnose paget’s disease?

Answer 25

technetium bone scan (tc bisphosphonate)

Question 26

If urine dipstick is poistive for blood but negative for erythrocytes what does that mean?

Answer 26

myoglobinuria eg due to rhabdomyololysis

Question 27

what enzyme abnromality can mumps cause?

Answer 27

mumps causes parotitis which can cause raised serum amylase!!!