22. Poor Urinary Output

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Question 3

In practice as a junior doctor, you want to diagnose and treat the pre-renal and post-renal causes. If you come to the conclusion that it is an intra-renal cause, call the renal physicians for an expert opinion.

Answer 3

Normal urine output requires:
1. Adequate blood supply to the kidneys.
2. functioning kidneys
3. flow of urine from the kidneys, down the ureters, into the bladder, and out via the urethra.

Question 4

You arrive on the ward and find Mr Chowdhury fast asleep and with normal observations apart from his anuria. You decide to look at Mr Chowdhury’s notes before waking him.
What clues in the notes might help you establish the cause of Mr Chowdhury’s poor urinary output?

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Question 6

Based on his fluid chart, make a table of Mr Chowdhury’s fluid intake/output and the change over time in his urine output?

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Question 11

What is the reason for Mr Chowdhury’s poor urinary output? How will you manage him?

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Question 14

What is the pathology?

Answer 14

= Cauda equine syndrome from disc prolapse (L4-5)

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Mrs Potter has oliguria (urine output <0.5ml/kg/hour) and AKI (oliuguria >6 hours and rise in creatinine >50% of baseline). She is essentially in renal failure. Possible reasons are:

• Prerenal Cause – A prerenal cause of oliguria (eg. Hypovolaemia, heart failure leading to reduced CO and renal hypoperfusion) is unlikely. Although Mrs Potter was likely hypovolaemic during the surgery, she is currently fluid overloaded (high JVP, pulmonary odema clinically).
• Postrenal Cause – A postrenal cause of oliguria (eg. Ureter damage, urinary tract obstruction) is unlikely in his case, as Mrs Potter is catheterized and has been passing urine since the operation, although it must be ruled out. If a postrenal cause is suspected, Mrs Potter should be referred to the urological surgeons.
• Renal Cause of Oliguria – A renal cause of oliguria (eg. Nephrotoxic medications, acute tubular necrosis due to previous hypovolamiea) is most likely in Mrs Potter by default, given that prerenal and postrenal causes appear unlikely. She is an elderly patient with type 2 diabetes, placing her at increased risk of renal failure, and has just suffered hypovolaemia during her surgery. It is likely her kidneys have suffered acute tubular necrosis from the transient hypovolaemia during her operation. As a renal cause is suspected, Mrs Potter should be referred to the renal physicians.

Question 17

4 Main complications of urethral bladder catheterization?

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Question 18

7 Main complications of chronic urinary retention?

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Question 19

What are the principle physiological mechanisms for regulating serum volume and serum osmolarity?

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Question 20

Which nerves, neurotransmitters, and receptors are responsible for bladder control and micturition? How is this applied to the pharmacological treatment of continence problems?

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Question 21

List 3 groups of drugs which common cause urinary retention?

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Question 22

What are 5 indications for dialysis in the acute setting? (3am)

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Question 23

A 55 year old man requests that is PSA levels be tested to check whether he has prostate cancer. Is the PSA test any good for screening for prostate cancer in asymptomatic men?

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Question 24

Is there any effective treatment for prostate cancer?

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Question 26

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