Acute Kidney Injury

Question 1

What is AKI?

Answer 1

Abrupt deterioration in renal function, usually over hours/days. Results in a failure to maintain fluid, electrolyte and acid-base balance.

Question 2

What is pre-renal AKI?

Answer 2

Decreased renal perfusion pressure

Question 3

What is intrinsic renal AKI?

Answer 3

Pathology of the vessels, glomeruli, or tubules-interstitium.

Question 4

What is post-renal AKI?

Answer 4

Obstruction of urinary outflow.

Question 5

What can causes the impaired perfusion in pre-renal AKI?

Answer 5

Cardiac failure
Sepsis 
Blood loss 
Dehydration
Vascular occlusion

Question 6

What can cause glomerulonephritis, small-vessel vasculitis and acute tubular necrosis in intrinsic renal AKI?

Answer 6

Drugs
Toxins
Prolonged hypertension

Question 7

What can cause Interstitial nephritis in intrinsic renal AKI?

Answer 7

Drugs
Toxins
Inflammatory disease
Infection

Question 8

What can cause obstruction of urinary flow in post-renal AKI?

Answer 8

Retroperitoneal fibrosis
Benign prostatic enlargement
Bladder cancer
Prostate cancer 
Cervical cancer
Urethral structure/valves
Meatal stenosis

Question 9

Define meatal stenosis.

Answer 9

Meatal stenosis is an abnormal narrowing of the urethral opening (meatus).

Question 10

Define oliguria?

Answer 10

Decreased urine output (<400ml/day)

Question 11

What is the most common underlying pathophysiological cause of AKI?

Answer 11

Acute tubular necrosis

Question 12

What causes acute tubular necrosis?

Answer 12

Under perfusion and reduced renal blood flow with intrarenal microvascular vasoconstriction leads to a decrease in the delivery of O2 increasing tubular hypoxia, leading to tubular necrosis.

Can also be caused by nephrotoxic drugs.

Question 13

Why is acute tubular necrosis reversible?

Answer 13

Tubular cells have the ability to regenerate rapidly and to reform the disrupted tubular basement membrane - which is why ATN is reversible.

Question 14

What are the 3 types of tubular renal AKI?

Answer 14

Acute tubular necrosis
Acute interstitial nephritis
Myeloma / Tumourlysis / Rhabdomyolysis

Question 15

What can cause acute interstitial nephritis?

Answer 15

Allergic reaction - drug related

Can also be caused by infection e.g UTI

Question 16

How do you test of post-renal obsturction of the urinary tract?

Answer 16

Ultrasound scan.

Question 17

Pruritis

Answer 17

Severe itching of the skin

Question 18

What is the major respiratory complication of AKI?

Answer 18

Shortness of breath due to pulmonary oedema.

Question 19

How is GFR affected in post renal AKI?

Answer 19

Postrenal failure is caused by obstruction of the urinary tract, leading to increased intratubular pressure and a fall in GFR.

Question 20

What can cause intratubular obstruction in intrinsic AKI?

Answer 20

Blockage of the tubules by protein (rhabdomyolysis and myeloma).

Question 21

What can urine biochemistry help identify in investigation?

Answer 21

Whether the AKI is renal or pre-renal.

Question 22

Why is an ultrasound carried out in cases of AKI?

Answer 22

To exclude post-renal obstruction.

Question 23

What are the two major concerns of AKI?

Answer 23

Hypovolaemia and hyperkalaemia.

Question 24

Hyperkalaemia

Answer 24

High potassium

Question 25

Hypernatremia

Answer 25

High sodium

Question 26

Interstitial nephritis is what type of AKI?

Answer 26

Intrarenal

Question 27

Interstitial nephritis is usually caused by what?

Answer 27

Type 1 or Type IV hypersensitivity reaction caused by drugs such as NSAID's, Diuretics or penicillin.

Question 28

What is renal artery stenosis?

Answer 28

The narrowing of one or both renal arteries.

Question 29

What can cause renal artery stenosis?

Answer 29

Atherosclerosis | Fibromuscular dyplasia

Question 30

Fibromuscular dysplasia

Answer 30

Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery.

Question 31

Post renal AKI

Answer 31

Due to obstruction of urine from the kidneys leading to a build up of pressure and urine.

Question 32

Name two nephrotoxic drugs that can cause intrarenal aki.

Answer 32

NSAIDS | ACE inhibitors

Question 33

Why does aki cause pulmonary oedema?

Answer 33

As the kidneys are unable to filter blood, there is a build up of fluid hypervolemia. Which leads to leakage of fluid into the lung causing pulmonary oedema.

Question 34

Nephrotoxic syndrome

Answer 34

Nephrotic syndrome is a kidney disorder that causes your body to pass too much protein in your urine. Nephrotic syndrome is usually caused by damage to the glomerular capillaries.

Question 35

What is the triad of symptoms seen in nephrotoxic syndrome?

Answer 35

Oedema Proteinuria Low albumin levels in the blood

Question 36

What is the major complication of nephrotoxic syndrome?

Answer 36

Oedema

Question 37

How does nephrotoxic syndrome increase the risk of clotting?

Answer 37

Nephrotic syndrome increases the amount of anti-thrombin III lost in the urine. Due to decreased protein in the blood the liver also activates protein synthesis increasing the number of clotting factors produced.

Question 38

NICE Criteria for AKI:

Answer 38

Rise in creatinine of ≥ 25 micromol/L in 48 hours Rise in creatinine of ≥ 50% in 7 days Urine output of < 0.5ml/kg/hour for > 6 hours

Question 39

Risk factors for AKI:

Answer 39

Consider the possibility of an acute kidney injury in patients that are suffering with an acute illness such as infection or having a surgical operation. Risk factors that would predispose them to developing acute kidney injury include: CONTRAST CT ACE inhibitors / NSAIDS both nephrotoxic usual risk factors for everything...

Question 40

Whenever someone asks you the cause of renal impairment always answer “the causes are pre-renal, renal or post-renal”. This will impress them and allow you to think through the causes more logically.

Answer 40

Whenever someone asks you the cause of renal impairment always answer “the causes are pre-renal, renal or post-renal”. This will impress them and allow you to think through the causes more logically.

Question 41

Treatment of AKI:

Answer 41

Fluid rehydration with IV fluids in pre-renal AKI. Stop nephrotoxic medications such as NSAIDS and antihypertensives that reduce the filtration pressure (i.e. ACE inhibitors). Relieve obstruction in a post-renal AKI, for example insert a catheter for a patient in retention from an enlarged prostate.

Question 42

What are the complications:

Answer 42

Hyperkalaemia Fluid overload, heart failure and pulmonary oedema Metabolic acidosis Uraemia (high urea) can lead to encephalopathy or pericarditis.