HateOCR
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HELP me please i really dont understand the answers to these questions (


1) A 77 year old man had surgery for colon cancer and now has a stoma (one end of the colon connected to an opening in the tummy). He becomes unwell and lethargic over a couple of days, his GP visits the patient at home. The carer complains that she had to change his stoma bag very frequently in recent days. The GP decides to admit the patient and in hospital his creatinine comes back as 744umol/L. He was previously not known to have renal disease. What is the most likely pathophysiological cause for his renal dysfunction:

Answer: pre-renal AKI


2) A 32 year old woman has been admitted with sudden abdominal pain and is now awaiting emergency surgery for a perforated appendix. She is found to have a creatinine of 430 umol/l. Her observation parameters are stable and she still has a good hourly urine output. She is also found to have mild hypocalcaemia and severe normocytic anaemia, with no history of bleeding, from which she remains asymptomatic. What is the most likely pathophysiological cause for her renal dysfunction:

Answer: Chronic Kidney Disease

3) A 72 year old man with no pre-existing renal disease has a cardiac arrest but fortunately is successfully resuscitated. He makes a good recovery and is waiting for bypass surgery however 5 days later despite support on the intensive care unit he remains anuric. What is the most likely underlying pathophysiological cause for his renal dysfunction

Answer: acute tubular necrosis

4) A 52 year old woman presents to her GP with a history of weight loss, nausea and poor appetite. Her blood pressure is 170/100mm/Hg and her ECG shows signs of left ventricular hypertrophy. Her creatinine was measured at 746umol/L. An Ultrasound scan reveals small kidneys on both sides. What is the most likely pathophysiological cause for her renal dysfunction:

Answer: CKD

5) A 55 year old man previously with no pre-existing renal disease has a history of recurrent stomach ulcers. Following a Gastroscopy he is found to be positive for Helicobacter pylori. His GP initiates triple eradication therapy with amoxicillin, clarithromycin and a proton pump inhibitor. He remains otherwise well without any new symptoms or intercurrent illness but a random blood test a week later reveals his Urea 24mmol/L, Creatinine 324umol/L, K+ 5.8mmol/L. What is the most likely underlying pathophysiological cause of the renal dysfunction:

Answer: renal aki (interstitial nephritis)
Last edited by HateOCR; 1 month ago
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moonkatt
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What is the question?
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HateOCR
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(Original post by moonkatt)
What is the question?
i just pasted the questions and answers now
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nexttime
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2) Doesn't strike me as a very satisfactory answer! Severe abdo pain, severe anaemia, severely raised creatinine, only 32, but sure guys I'm sure it'll be fine

What are your initial thoughts OP?
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HateOCR
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(Original post by nexttime)
2) Doesn't strike me as a very satisfactory answer! Severe abdo pain, severe anaemia, severely raised creatinine, only 32, but sure guys I'm sure it'll be fine

What are your initial thoughts OP?
i think CKD makes sense because chronic kidney damage would lead to eventual decrease in EPO so anaemia? WHat do you reckon? i have no idea how to answer these kidney disease questions i find them really hard ( these are questions and answers from my medical school
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(Original post by HateOCR)
i think CKD makes sense because chronic kidney damage would lead to eventual decrease in EPO so anaemia? WHat do you reckon?
It definitely has features that within the context of a med school question are pointing to CKD. What you say is accurate regarding EPO.

My point is regarding how this patient would be treated in real life, where things don't always follow the textbook. This person has severe abdo pain, which could have a host of intra-abdominal causes, many of which might result in severe bleeding. They have a normocytic anaemia, but acute bleeding would also be normocytic. They have a low calcium, which can be a sign of CKD, but its also very common in people who are very sick and its one of those things that is sometimes just abnormal without any particular explanation.

The main things that IRL would make me less worried are the ok observations (but remember that a young person can maintain their BP in particular despite massive blood loss, with it only dropping right at the end before they arrest) and the ok urine output (but again IRL this can be mis-measured, mis-recorded etc).

The other aspect to this case is that a 32 year old with a creatinine of 400+ which if chronic is hugely worrying! They are heading for complete kidney failure soon, and are likely going to need extensive investigation and potentially putting on the renal transplant list. To just label it as CKD with no further explanation... very unsatisfactory!

But within the context of a med school question, where they rarely give you irrelevant details (like the calcium), the "correct" answer is CKD yes.

i have no idea how to answer these kidney disease questions i find them really hard ( these are questions and answers from my medical school
If you give us your best guess we will correct and help
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Rainy Times
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So if you split it into CKD and AKI first of all, have a look at the definitions for each and how the causes of AKI get split into pre-renal, renal and post-renal. Osmosis do some pretty good videos which are available for free on youtube if you don't know where to start.

1. The patient has no known history of kidney disease, and if he had a chronic kidney problem with a creatinine of 744 he would likely be having a few symptoms. So it's quite likely he has some sort of acute deterioration right, especially given a recent history of surgery. If his stoma bag is being changed more frequently that means he's probably losing quite a bit of fluid from it, causing dehydration which is a pre-renal cause of AKI (i.e. the problem arises before the kidneys) which fits with his symptoms.

2. The features of CKD here are the normocytic anaemia due to loss of Erythropoietin and the "mild hypocalcaemia" which in MCQ language probably means secondary hyperparathyroidism due to loss of renal 1alpha-hydroxylase. These are both seen with CKD rather than in the acute setting, pointing to the cause of her renal dysfunction being chronic rather than acute.

3. The continuing anuria means the patient meets one of the definitions for an AKI. Acute Tubular Necrosis is one of the causes of an AKI which you probably need to know a bit about, they get a pathognomic finding on urine microscopy ("muddy brown casts") and the way they urinate or not tends to follow a pattern (in textbooks) which makes it easy to ask exam Qs on. In this case the cardiac arrest caused the ischaemia and necrosis.

4. Again they're just listing a few of the complications of CKD - hypertension is associated with CKD due to tubuloglomerular feedback which ramps up renin secretion when tubular sodium flow drops, but the main point here is probably the small kidneys on ultrasound which is associated with most causes of CKD. Secondary HTN and renal disease go hand in hand so it's probably worth looking at a few of the renal causes of HTN.

5. Acute interstitial nephritis is another cause of an intra-renal AKI. Again looking at the case they're getting you to look at the features of an AKI with the azotemia and hyperkalaemia and then the cause. You can get raised blood and urinary eosinophils with AIN too. The most likely cause here is Acute interstitial nephritis due to the drugs he's on. I remember the "4 Ps" for drugs causing AIN: (and he was recently started on 2 of them)
Pee: Diuretics
Pain-free: NSAIDs
Penicillins
PPIs
There's loads of others but those are the ones that seem to get tested.

Honestly once you've got your head around some of the physiology and looked at some of the causes of CKD/AKI the best thing to do is loads of MCQs via Passmedicine/Pastest, easiest way to drill all the "associations" in I've found.
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Asklepios
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(Original post by nexttime)
If you give us your best guess we will correct and help
Agree with Q2. You can get hypocalcaemia with AKI and there are a million and one causes of anaemia.

It would be good to see previous creatinine levels before labelling as CKD. Or if not, secondary hyperparathyroidism would be more specific for chronicity.
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Hype en Ecosse
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(Original post by Asklepios)
Agree with Q2. You can get hypocalcaemia with AKI and there are a million and one causes of anaemia.

It would be good to see previous creatinine levels before labelling as CKD. Or if not, secondary hyperparathyroidism would be more specific for chronicity.
I looked after a lady yesterday who has had "CKD4" written on her notes for approximately 3 years.
Her creatinine at presentation was 66. ^^
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Asklepios
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(Original post by Hype en Ecosse)
I looked after a lady yesterday who has had "CKD4" written on her notes for approximately 3 years.
Her creatinine at presentation was 66. ^^
According to the MDRD eGFR equation, if she's 10531 years old, then that creatinine would give an eGFR of 29 so not impossible.
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