11. EMQ on Enzymes and Chemistry Flashcards
Creatine kinase is the protein in your muscle, what is the waste produce that it generates?
Creatinine
As people have a fixed muscle mass, you make creatinine at …
a fixed rate
As people have a fixed muscle mass, you make creatinine at a fixed rate. Therefore, when the kidneys fail…
creatinine goes up
What will happen to AST following an acute MI? Why?
AST will increase following an acute MI because AST is found within the myocytes
When are AST levels increased and for how long?
AST goes up about 3 days after an MI and remains for around 14 days (3-14 days)
Which enzymes increase following an MI?
Troponins, CK (MB), AST, LDH
Why can rhabdomyolysis lead to acute kidney injury?
Because myoglobin is very nephrotoxic
What do you give patients with rhabdomyolysis?
IV bicarbonate
Why do you give IV bicarbonate to patients with rhabdomyolysis?
If patients have a very high CK because of muscle breakdown, it can lead to renal failure. To prevent this from happening, you give them IV bicarbonate which allows them to pee out all the extra CK
ALT and AST in patients with viral hepatitis
ALT will be higher than AST
ALT and AST in patients with chronic alcoholic cirrhosis
AST will be higher than ALT (2:1) in patients with chronic alcoholic cirrhosis
What are the levels of acid phosphatase in prostate cancer?
Acid phosphatase rises
What is the vitamin D level in primary hyperparathyroidism and why?
The vitamin D level is LOW. This is because PTH activates 1-alpha hydroxylase meaning that vitamin D is consumed (i.e. it is activated)
In acute renal failure that is caused by dehydration, what will rise the most?
urea
In chronic renal failure caused by a fall in GFR, what will rise the most?
creatinine
Diabetes, as a cause of CKD, is less rapidly progressive than other causes of renal impairment, true or false
false, it is much more rapidly progressive than other causes of renal impairment
With diabetes, you are likely to reach end-stage renal failure within a year if you have a creatinine ….
> 200 micromol/L
Having a high creatinine does or does not mean that you need dialysis?
Does NOT
What are indications for dialysis?
Hyperkalaemia, acidosis (NOTE: a lot of these patients are given sodium bicarbonate to try and minimise the acidosis) and pulmonary oedema
What is a marker of glucose control over the last 3 weeks?
Fructosamine
Why use fructosamine as a marker of glucose control (over last 3 weeks)?
- It is important to have good diabetic control during pregnancy
- You also cannot wait for 3 months to assess blood glucose control because the pregnancy only lasts 9 months
- It is also important to monitor blood glucose control because as the pregnancy progresses their control will deteriorate (because all the hormones in pregnancy are insulin-resistant)
What is the FreeStyle Libre?
Soon, you will be able to use a FreeStyle Libre (a probe that you can put on your arm and swipe to get a reading)
In Paget’s disease, what is there an increase in activity of?
Both osteoclasts and osteoblasts
What does an increase in osteoblasts and osteoclasts in Paget’s disease lead to?
Increase in ALP and osteocalcin
What is a key feature of Paget’s disease?
A bowed tibia is a key feature of Paget’s disease (it will also be warm)
Most people with Paget’s disease will be ASYMPTOMATIC but what to they have a high risk of?
High risk of fractures
What is the treatment for Paget’s disease?
Bisphosphonates (only if it is painful). This is because the bone that is formed with calcium bisphosphonate is not degradable by osteoclasts.
What is the scan that ALL oncology patients have looking for bony metastases?
Technetium bisphosphonate scan
Why do the kidneys always show up in a technetium bisphosphonate scan?
Because the label is excreted by the kidneys
What is a technetium 99m (pertechnetate) scan used for?
To look for iodine uptake by the thyroid gland
What is a PET scan used for?
To look for abdominal metastases.
What is sometimes used as a marker in PET scans?
FDG (fluorodeoxyglucose) is sometimes used as a marker (NOTE: the scan is labelled as an FDG PET Scan)
Why is FDG PET scan not specific?
Glucose is taken up by ANY active cell. Cancer cells are more active so they will take up more FDG.
Why might you want to take a CT scan image quickly after injecting the contrast?
- Once you inject the contrast, you may want to take an image quite quickly afterwards to get a picture of the body in the arterial phase (i.e. once the contrast has gone from the vein to the heart and into the systemic circulation)
- If you wait a bit longer, the contrast will move through the gut and you will be able to get a photo in the portal phase
- If you wait even longer, you will get a delayed scan during the venous phase
You can do a triple phase CT scan - what does this do?
This looks at the arterial, portal and venous phases. However, this involves administering 3 x as much radiation.
The CT scan can be superimposed with a radiolabelled scan using …?
Gallium 68 (this is also called a gallium dotatate scan)
Gallium can be stuck onto a somatostatin analogue so that …
it goes to tissues that have somatostatin receptors (i.e. any neuroendocrine cell)
Why does the spleen always appear hot in a Gallium DOTATATE scan?
The spleen has a lot of receptors for somatostatin so it will always appear hot (so, localisation in the spleen is a telling feature of Gallium 68 scans using somatostatin analogues)
Apart from the spleen what else appears hot in a Gallium 68 scan?
Kidneys and adrenals
What is an MIBG scan?
MIBG is a precursor for adrenaline that is used for identifying phaeochromocytoma
Gallium dotatate picks up any neuroendocrine tumour, which includes…
Phaeochromocytomas and insulinomas
What is a useful scan for abdominal mets from cancer?
Fluorodeoxyglucose (FDG) PET scan
What is a useful scan for bony mets?
Tc bisphosphonate
What is a useful scan for primary neuroendocrine tumours (insulinomas)?
Gallium 68 dotatate
What is a useful thyroid scan?
Tc 99 pertechnetate
What is a useful parathyroid scan?
Sesta MIBI
What is a useful phaeochromocytoma scan?
MIBG
What is MIBI used by?
Parathyroid glands and myocardium
What will you see with MIBI in a myocardial infarction?
An area where there is no uptake of MIBI
With all of these scans, why do you combine them with a CT scan?
To get more information about the location of the issue
ALT is important in gluconeogenesis, true or false?
False, AST is important in gluconeogenesis
What does damage to different zones of the liver cause?
Causes different patterns of abnormalities in LFTs
Why does ALP rise the most in diseases that cause obstructive jaundice?
The zone around the bile duct in the portal triad has a lot of ALP
What happens in acute alcoholic hepatitis?
Patient likely to have a long alcohol history (with other signs such as Dupuytren’s contracture) and they suddenly become ill because of alcoholic hepatitis
How to treat acute alcoholic hepatitis?
With support and reducing inflammation with steroids, they will recover
In acute alcoholic hepatitis, a lot of hepatocytes die but a few will survive and attempt to regenerate. What happens when they regenerate?
When cells regenerate, they do NOT grow nicely into hexagons. The grow into nodules, This means that the blood from the portal triad has to go around the nodules before arriving at the central vein. If the patient gets another bout of alcoholic hepatitis, they will develop even more nodules.
If a patient keeps getting acute alcoholic hepatitis, and develops more nodules, what can this lead to?
Nodular cirrhosis, which can then lead to portal hypertension.
Why does nodular cirrhosis lead to portal hypertension?
Nodules mean that the blood from the portal triad has to go around the nodules before arriving at the central vein. In nodular cirrhosis, the blood has an even tougher route around the nodules to get to the central vein. This leads to a rise in pressure (portal hypertension).
Where do varices occur, caused by portal hypertension due to nodular cirrhosis?
Varices occur at sites of porto-systemic anastomosis
In cirrhosis, what rises the most?
AST
What does the portal triad consist of?
hepatic artery, bile duct and portal vein
