CHEMPATH: EMQs on enzymes and chemistry Flashcards Preview

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Flashcards in CHEMPATH: EMQs on enzymes and chemistry Deck (32)
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1
Q

Which one is increased in a patient with Paget’s disease of the bone?

A

C - alkaline phosphatase (ALP) and osteocalcin

Increased due to increased activity of both osteoblasts (causes raised osteocalcin) and osteoclasts

2
Q

List 3 features of Paget’s disease.

A
  • Asymptomatic
  • Bowed tibia (it will also be warm)
  • High risk of fracture
3
Q

Which one is increased in a patient with osteomalacia?

A

PTH

Lack of vitamin D –> 2nd HPT –> high PTH

4
Q

Which one is increased in a patient following an acute myocardial infarction?

A

Answer: troponins, CK (MB), AST, LDH

(AST is important in gluconeogenesis)

5
Q

What is raised in Addison’s disease?

A

potassium

6
Q

What is most raised in jaundice caused by a gallstone?

A

ALP - consider liver zonation

7
Q

Which one is most increased in a patient with jaundice caused by viral hepatitis?

A

ALT

8
Q

Which one is most increased in a patient with jaundice caused by chronic alcoholic cirrhosis?

A

AST

9
Q

Which one is most increased in a patient with prostatic carcinoma?

A

Acid phosphatase

10
Q

Which scan would you use to look for bony mets?

A

Bone scan Tc bisphosphonate

11
Q

What investigations are useful to make the diagnosis of Paget’s disease?

A

Bone scan with Tc bisphosphonate - used to see bone turnover in cancer patients to look for bony metastases

12
Q

Name another technetium 99 scan.

A

Technetium 99m (pertechnetate) scan for iodine uptake by thyroids:

  • Diffuse uptake = diffuse goitre / Graves’ disease
  • Unilateral uptake / hot nodule = adenoma

Tc99m-sestamibi for parathyroids - absorbed faster by a hyperfunctioning parathyroid gland than by a normal parathyroid gland

13
Q

What nuclear scan is used to look for abdominal metastases in oncology? What marker is used?

A

FDG-PET Scans – looks at glucose uptake​

Marker = FDG (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
14
Q

What feature of a scan will indicate that you are looking at a Gallium 68 DOTATATE scan using somatostatin analogues?

A

Spleen will appear hot - because it has a lot of somatostatin receptors.

  • Kidneys, pancreas, cysts in kidneys, and adrenals will also appear hot.
  • Gallium 68 stuck onto a somatostatin analogue will go to tissues that have smatostatin receptors i.e. any neuroendocrine cells.
15
Q

Which scan would you use to visualise primary neuroendocrine tumours?

A

Neuroendocrine tumours (insulinomas)

16
Q

Which radionucleotide scan would you use to identify phaechromocytomas?

A

MIBG (Meta-Iodobenzylguanidine) Scan

+ Gallium dotatate - picks up any neuroendocrine tumour (includes phaeochromocytoma and insulinomas)

17
Q

Which radionucleotide scan can you use to look at the parathyroids?

A

Sestamibi / Sesta MIBI (scintigraphy)

  • Tc99m-sestamibi is absorbed faster by a hyperfunctioning parathyroid gland than by a normal parathyroid gland
18
Q

How would the myocardium appear on Sestamibi scan during MI?

A

There would be an area of lack of uptake

19
Q
A
20
Q

Label these parts of the portal triad.

A
21
Q

Which liver zone is damaged in obstructive jaundice causing a rise in ALP?

A

Zone 1 - around the bile duct in the portal triad

22
Q

What is raised in someone with primary HPT?

A

Calcium

23
Q

What is low in primary HPT?

A

vitamin D

24
Q

What rises the most in acute renal failure?

A

Urea - if caused by dehydration

25
Q

What rises the most in chronic renal failure?

A

creatinine - because there is a fall in GFR

26
Q

What is a marker of glucose control over last 3 months?

A

HbA1c

27
Q

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

A

fructosamine

Used in pregnancy where you cannot wait 3 months to assess HbA1c. Glucose control becomes very important later in pregnancy as more insulin resistance may develop.

28
Q

When will AST rise after MI and how long will it remain elevated?

A
  • Goes up ~3 days after an MI
  • Remains for around 14 days (3-14 days)

Enzymes that increase following MI:

  • Troponins (B, D)
  • CK MB (C)
  • Myoglobin (A)
  • AST
  • LDH
29
Q

Why does rhabdomyolysis cause acute kidney injury?

A

Myoglobin is very nephrotoxic

Very high CK (from muscle breakdown) will lead to renal failure

30
Q

How can you prevent renal failure after rhabdomyolysis?

A

IV bicarbonate - allows excretion of extra CK

31
Q

What is the ratio of AST to ALT in differrent conditions?

A

ALT> AST - in patients with viral hepatitis

AST to ALT of 2:1 - in patients with chronic alcoholic cirrhosis

32
Q

What are the main 5 indications for dialysis?

A
  • Indications for Dialysis:
    • Refractory hyperkalaemia
    • Refractory fluid overload
    • Metabolic acidosis
    • Uraemic symptoms (encephalopathy, nausea, pruritis, malaise, pericarditis)
    • CKD stage 5 (GFR <15mL/min)

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