Chemical Pathology - EMQs on Enzymes, Chemistry

Question 1

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

Answer 1

Bone scans: Tc bisphosphonate

Thyroid scans: Tc pertechnate

Question 2

which type of nuclear medicine test is most useful for identifying abdominal metastasis of cancer cells themselves?

Answer 2

FDG-PET
fluorodeoxyglucose
non-specific marker as glucose is taken up by ANY active cell
cancer cells are more active so they will take up more FDG

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 in all neuroendocrine cells)

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
meta-Iodobenzylguanidine
MIBG is a precursor for adrenaline that is used for identifying phaeochromocytoma

NOTE: Gallium dotatate picks up any neuroendocrine tumour (includes phaeochromocytoma and insulinomas)

Question 6

wecall 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/GGT

Question 8

describe 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’s a consequent of rhabdomyolysis on kidney after an MI? how can this be prevented?

Answer 10

renal failure

IV sodium bicarb to excrete excess creatinine kinase

Question 11

acid phosphatase rises in what condition?

Answer 11

prostate cancer

Question 12

AST will be elevated compared to ALT in what condition?

Answer 12

AST will be higher than ALT (2:1) in patients with chronic alcoholic cirrhosis

Question 13

vitamin D blood test measures what specific compound?

Answer 13

calcidiol (inactivated form)

this is then activated by 1 alpha hydroxyls under action of PTH

Question 14

in acute renal failure caused by dehydration what will rise the most?

Answer 14

urea

Question 15

in chronic renal failure caused by a fall in GFR what will rise the most?

Answer 15

creatinine

Question 16

what’s a maker of glucose control over past 3 weeks or so?

Answer 16

fructosamine

often used in pregnancy when can’t wait for 3 months using HbA1c

Question 17

what’s the treatment of paget’s?

Answer 17

bisphosphonates (only if painful) – bone formed with Ca2+ bisphosphonate not degraded by osteoclasts

Question 18

which LFT result will be most deranged in jaundice due to alcoholic hepatitis?

Answer 18

AST

may see duputryen’s contracture

Question 19

what electrolyte is raised in Addison’s?

Answer 19

potassium