Renal - Acute Kidney Injury

Question 1

What is the definition of acute kidney injury?

Answer 1

An acute drop in kidney funciton from the patient’s baseline of normal.

Question 2

How is AKI diagnosed?

Answer 2

By measuring the patient’s serum creatinine

Question 3

What is the NICE criteria for AKI?

Answer 3

Urine output of <0.5ml/kg/hour for over 6 hours

Rise in creatinine of >50% in 7 days OR rise in creatinine of >25 micromol/L in 48 hours

Question 4

List some risk factors for developing an AKI

Answer 4

Nephrotoxic medications
Heart failure
Liver disease
Dehydration
Sepsis
Old age
CKD
Diabetes
Contrast medium in CTs
Cognitive impairment

Question 5

How can we differentiate the causes of Acute Kidney injury?

Answer 5

They will either be
Pre-renal
Renal
Post Renal

Question 6

What is the most common form of AKI

Answer 6

Pre renal

Question 7

How does pre renal AKI occurt?

Answer 7

There is reduced perfusion of the kidneys due to an inadequate blood supply

Question 8

List the main causes of pre-renal AKI

Answer 8

Dehydration
Hypotension / shock
Heart failure
(Renal artery stenosis)

Question 9

Define Renal AKI:

Answer 9

The intrinsic disease in the kidneys has led to a reduced filtration of blood

Question 10

What are the causes of a renal AKI?

Answer 10

Glomerulonephritis
Acute Tubular necrosis
Interstitial nephritis

Question 11

Describe the physiology of how a post renal AKI occurs?

Answer 11

There is an obstruction to the outflow from the kidney which leads to a back pressure into the kidney, reducing the kidney function.
AKA obstructive uropathy

Question 12

List some causes of post renal AKI:

Answer 12

Kidney stones
Ureter strictures
Masses such as cancer in abdo
ENlarged prostate / prostate cancer

Question 13

What investigation should be done if you cannot find the source of the post renal AKI?

Answer 13

USS of the urinary tract to source the blockage

Question 14

What are some complications of an AKI?

Answer 14

Hyperkalemia
Fluid overload - from management
Metabolic Acidosis
Uraemia –> leading to encephalopathy and / or pericarditis

Question 15

If protein and blood are found in the urinalysis what could be the cause of the AKI?

Answer 15

Acute nephritis

or infection

Question 16

Give some examples of illnesses which can lead to/ make you more vulnerable to, acute tubular necrosis?

Answer 16

Cholestatic jaundice
DIC
Liver failure
Pregnancy
Pancreatitis

Question 17

What are some acute features of acute tubular necrosis?

Answer 17

uraemia symptoms:
Anorexia
Vomiting
Pruritis
Drowsiness
Fits
Nausea
Epistaxis

Question 18

Define Acute tubular necrosis:

Answer 18

Damage and death of the epithelial cells of the renal tubules.

Question 19

Acute tubular necrosis is reversible - true or false?

Answer 19

True

The epithelial cells have the ability to regenerate

Question 20

How long does it usually take to recover from AKI with acute tubular encroiss?

Answer 20

7 - 21 days

Question 21

Rhabdomyolysis is a form of ____ AKI?

Answer 21

Renal

Question 22

List some toxins which can cause acute tubular necrosis:

Answer 22

Gentamicin
NSAIDs
Lithium
Heroin
Radiology contrast dye

Question 23

What is a pathognomonic finding on urinalysis, specific to acute tubular necrosis?

Answer 23

Muddy brown casts

Renal tubular epithelial cells in the urine

Question 24

In Acute Tubular necrosis, what 3 things will be raised on biochemistry?

Answer 24

Urea
Potassium
Phosphate

Question 25

In acute tubular necrosis, what 3 things will be low on biochemistry?

Answer 25

pH Calcium Sodium

Question 26

In acute tubular necrosis what part of the kidney specifically is blood flow reduced?

Answer 26

Renal cortex

Question 27

What is the main symptom of an AKI resulting from acute tubular necrosis?

Answer 27

Oliguria (reduced urine output)

Question 28

Acute tubular necrosis resolves spontaneously. True or false?

Answer 28

True The main aims of management is preventing uraemia hyperkalaemia etc and reducing sepsis risks.

Question 29

What is a severe outcome of acute tubular necrosis if it does not resolve quickly?

Answer 29

Cortical necrosis Caused by reduced blood flow to the renal cortex, and instead of regenerating it heals via scarring (glomerulosclerosis) and eventually necrosis.

Question 30

In an AKI what would be indicators for management with dialysis?

Answer 30

Pulmonary oedema Persistent hyperkalemia despite intervention Severe metabolic acidosis Uraemic pericarditis / encephalopathy etc Drug overdose (to remove drug)

Question 31

List some medications which must be stopped in an AKI as they may worsen the renal funciton?

Answer 31

``` NSAIDs ACE inhibitors ARBs Aminoglycosides Diuretics ```

Question 32

In hyperkalemia, which drug is given for cardiac stabilization purposes?

Answer 32

Calcium gluconate IV

Question 33

How does insulin and dextrose infusion, and sometimes nebulised salbutamol, help in the management of hyperkalemia?

Answer 33

It temporarily reduces the k+ by shifting it from the extracellular to the intracellular compartments.

Question 34

What medications can be given in hyperkalemia to reduce the potassium levels by removing them from the body?

Answer 34

Calcium resonium (orally or enema) (Loop diuretics - use with caution) Dialysis

Question 35

Give some examples of medications which are suitable to continue in an AKI?

Answer 35

``` Warfarin Aspirin (at a cardioprotective dose) Paracetamol Statins Clopidogrel ```

Question 36

Give some examples of medications that are nephrotoxic but do not worsen AKI so can be stopped or continued during an AKI?

Answer 36

Lithium Digoxin Metformin

Question 37

What would brown granular casts in the urine be suggestive of?

Answer 37

renal AKI from Acute tubular necrosis

Question 38

How can you differentiate between a pre renal and renal cause of an AKI?

Answer 38

Fluid challenge If they respond well the cause is probably pre renal

Question 39

In acute tubular necrosis, the serum urea:creatinine ratio will be normal. True or false?

Answer 39

True In pre renal causes the ratio will be higher

Question 40

In a Renal AKI, will the urine osmolality be high or low?

Answer 40

Low roughly <350 mOsm/kg

Question 41

In acute tubular necrosis the urine concentration of sodium will be low. True or false?

Answer 41

False high excretion of sodium is suggestive of an impaired exchange at the tubule which indicates acute tubular necrosis