Session 11: Group Work

Question 1

Which patient characteristics can make serum creatinine an unreliable measure of kidney function and explain why.

Answer 1

Male

Big muscly

Black

Old

Female

Small

White

Question 2

Which factors are considered in the calculation of an eGFR.

Answer 2

Serum creatinine

Size

Age

White or black

Sex

Question 3

Why is eGFR an unhelpful test in AKI?

Answer 3

It assumes that the creatinine levels are relatively stable over a few days and not rapidly changing. THis is why eGFR is not valid in AKI.

Question 4

What happens to urea in terms of filtration, reabsorption and secretion?

Answer 4

It is filtered and then 50% are reabsorbed in the PCT

More reabsorbed in the collecting duct of the medulla as well.

IT can go and be secreted back into the thin ascending limb again for recycling and working as an effective osmole

Question 5

How will the serum urea levels be in

a - AKI due to volume depletion

b - malnutrition

c - upper GI bleed

Answer 5

A - high serum urea (low volume leads to more Na+ reabsorbed and therefore less urea that is being secreted)

B - lower serum urea (less urea produced from proteins)

C - High serum urea (blood digested into urea)

Question 6

List symptoms that a patient may present with that are present if the kidneys are failing?

Answer 6

Hyperkalaemia

Uraemia

Malaise

Lethargy

Insomnia

Fatigue

Aches

Pruritus

Bone disease

Acidosis

Oliguria

Anuria

Oedema

Question 7

What is the difference between oliguric and non-oliguric patients with AKI?

Answer 7

Oliguric don’t wee as much as non-oliguric.

Oliguria is defined as less than 500 ml of urine produced in 24 hours

Question 8

What is pre-renal AKI and what might cause this?

Answer 8

Hypoperfusion such as hypovolaemia (septic or distributive shock)

Renal artery stenosis

NSAIDs

ACE inhibs

ARBs

Question 9

What is post-renal AKI and what might cause this?

Answer 9

Obstruction of urinary tract

Kidney stones

Urinary calculi

Cancer of urinary tract

Question 10

Define acute tubular injury (ATI)

Answer 10

Damage to the cells of the tubules and interstitium of the kidneys

An intrinsic kidney injury

Question 11

What are the risk factors or possible causes of ATI?

Answer 11

Pre-renal casues

NSAIDS

Nephrotoxic durgs like antiobiotics (gentamicin)

Contrast

Myoglobin

Bilirubin

Smoking

Hypertension

Diabetes

Question 12

What two blood chemistry values are reflective of the kidneys ability to excrete waste?

Answer 12

Serum creatinine

Urea

Question 13

Describe the patient’s acid-base status and suggest why this has occurred in the patient.

Answer 13

Metabolic acidosis as well as respiratory acidosis.

Metabolic acidosis because of the breakdown of muscle in his left leg leading to lactic acidosis. Also renal failure leading to a failure to reabsorb bicarbonate.

He is also on opiates leading to hypoventilation and retention of CO2 leading to respiratory acidosis.

Question 14

AKI due to rhabdomyolsysis is suspected in this case. What characteristic of this urine is suggestive of this diagnosis and what circumstance might have caused the rhabdomyolysis?

Answer 14

Very dark brown urine and haematuria.

Possible DVT or thrombophlebitis.

Possible compartment syndrome

Question 15

Rhabdomyolysis is caused by muscle damage. What is released that causes AKI?

Answer 15

Myoglobin which is nephrotoxic

Question 16

How would you confirm your diagnosis?

Answer 16

Creatine kinase

Serum creatinine

Question 17

Explain the mechanisms that have led to a high K+ in this patient.

Suggest three different mechanisms that may be contributing to hyperkalaemia in this patient.

Answer 17

Low glucose leading to less insulin and therefore less K+ going into cells.

Cell breakdown leading to expelled K+

Acidosis which means that H+ is being transported into cells in exchange for K+

Na+ is spared in exchange for K+ in the kidneys

Question 18

Does that patient’s creatinine result surprise you?

Answer 18

No the kidneys are shutting down and can’t fitler the serum creatinine.

There is also increased creatine kinase which will lead to more creatinine (increased muscle breakdown)

Question 19

Would you expect his anion gap to be normal?

Answer 19

Increased due to lactic acidosis

Question 20

What is the principle of managing patient’s with this condition?

Answer 20

Fluids

Insulin+glucose

Naloxone

Question 21

What is the most likely cause of her AKI?

Answer 21

Hypoperfusion

Question 22

What factors have contributed?

Answer 22

Low BP

Ace inhibs

NSAIDs

Diarrhoea + vomiting

Question 23

Is her pulse rate higher or lower than you would expect?

Why?

Answer 23

Lower

Would have expected higher in order to compensate for the low BP

Question 24

Why is the skin around her legs wrinkled?

Answer 24

Fluid depletion

Question 25

Are her sodium and potassium what you would expect them to be?

Suggest and explanation for her electrolyte results.

Answer 25

Na+ should be low but the as there is only loss of Na and H2O and also only replacement of water.

K+ should be high in AKI but is rather low which might happen in diarrhoea and vomiting

Question 26

What would be your initial management of this patient?

Are there any particular precautions in this case?

How would you minimise the risk of harm?

Answer 26

Fluid replacement with Na+ and K+

Stop bisoprolol, ramipril and furosemide

Watch out for heart failure