7: Acute kidney injury

Question 1

What is the definition of AKI?

Answer 1

Abrupt (<48h):

increase in serum creatinine (>26.4)

increase in creatinine by 50%

reduction in urine output

one of the above

Question 2

What needs to be done before you can diagnose a patient with AKI?

Answer 2

Attempt fluid resuscitation

Exclude obstruction

Question 3

What are some pre-renal causes of AKI?

Answer 3

Hypovolaemia

Hypotensive (cardiogenic, septic, anaphylactic)

Certain drugs

Question 4

What are the definitions of

a) normal urine output
b) oligouria?

Answer 4

a) 0.5ml/kg/hr
b) < 0.5ml/kg/hr

Question 5

If patients are sick (e.g diarrhoea, vomiting), which drugs should they stop to prevent AKI?

Answer 5

Antihypertensives

e.g ACE inhibitors, ARBs, diuretics

Question 6

What happens if pre-renal AKI isn’t treated?

Answer 6

Acute tubular necrosis

Question 7

What commonly causes pre-renal AKI?

Answer 7

Hypovolaemia, hypotension due to

sepsis

dehydation

Also:

drugs

rhabdomyolysis

Question 8

What are signs and symptoms of dehydration?

Answer 8

Hypovolaemia

Tachycardia

Low urine output

Low JVP

Cap refill > 2s

Oedema

Question 9

How is pre-renal AKI treated?

Answer 9

Fluid challenge for hypovolaemia and hypotension

500ml 0.9% NaCl over and over until improvement

Question 10

What are some

a) vascular
b) glomerular

causes of renal AKI?

Answer 10

a) Vasculitis, renovascular disease (renal artery stenosis)

b) Glomerulonephritis

Question 11

Which drugs can cause nephritis?

Answer 11

Antibiotics

PPIs

Gold, pencillamine

methotrexate

gentamicin

Question 12

What are the symptoms of AKI?

Answer 12

Constitutional - anorexia, weight loss, fatigue..

N&V

Itch

Fluid retention

Question 13

Which infection commonly causes glomerulonephritis?

Answer 13

GAS

Question 14

What types of GN are suggested by

a) sore throat in the past 2-3 weeks
b) rash
c) joint pain
d) haemoptysis?

Answer 14

a) Post-streptococcal glomerulonephritis

b) Vasculitic nephritis

c) Lupus nephritis

d) Goodpasture’s syndrome

Question 15

Why can compartment syndrome cause AKI?

Answer 15

Rhabdomyolysis

Question 16

What are some blood tests which should be done for those with AKI?

Answer 16

U&Es - particularly hyperkalaemia

FBC - for anaemia, prolonged clotting

Question 17

What’s a quick test which can be done to pick up proteinuria / haematuria?

Answer 17

Urinalysis

Question 18

What imaging is first line for looking at the kidney?

What can it pick up?

Answer 18

USS

Stones

Question 19

Which causes of AKI are associated with

a) ANA

b) ANCA

c) GBM antibody?

Answer 19

a) SLE (not really)

b) Small vessel vasculitis

c) Goodpasture’s syndrome

Question 20

What are signs of multiple myeloma on blood test?

Answer 20

Hypercalcaemia

Anaemia

Question 21

When would a renal biopsy be indicated?

Answer 21

Rapidly progressing GN

Positive antibodies for something

Don’t know what’s wrong

Question 22

Which scan is used to guide renal biopsies?

Answer 22

USS

Question 23

What are some signs of life-threatening AKI?

Answer 23

Hyperkaleamia

Resistant fluid overload (pulmonary oedema with no urination)

Severe metabolic acidosis

Severe uraemia

Question 24

What causes post-renal AKI?

Answer 24

Obstruction of urinary tract

Question 25

What problem is caused by an obstructed urinary tract?

Answer 25

**Hydronephrosis**

Question 26

How does hydronephrosis cause AKI?

Answer 26

**Loss of kidney's ability to concentrate urine**

Question 27

What can cause obstruction of the urinary tract?

Answer 27

**Renal calculi** **Malignancy** **Strictures** **Prostate enlargement**

Question 28

What is a life-threatening electrolyte imbalance caused by AKI?

Answer 28

**Hyperkalaemia**

Question 29

What causes death in hyperkalaemia?

Answer 29

**Arrythmia**

Question 30

What is the normal range of **potassium concentrations** in the body? What level is **hyperkalaemic**? What level is **life-threatening**?

Answer 30

**3.5 - 5.0** Hyperkalaemia: **\>**= **5.5** Life-threatening hyperkalaemia: \>= **6.5**

Question 31

How is hyperkalaemia assessed?

Answer 31

**U&Es** **ECG** **Muscle weakness**

Question 32

What are the ECG manifestations of hyperkalaemia?

Answer 32

**Bradycardia** **Tall, tented T waves** **Prolonged PR interval**

Question 33

What drug is given first to protect the myocardium in **hyperkalaemia**?

Answer 33

**Calcium gluconate**

Question 34

What is given to a) protect the myocardium b) move K+ into cells c) correct metabolic acidosis d) prevent K+ absorption in the bowel in a patient with hyperkalaemia?

Answer 34

**a) Calcium gluconate** **b) IV insulin** + **dextrose** (to prevent hypoglycaemia, **INH salbutamol** **c) Sodium bicarbonate** **d) Calcium resonium**

Question 35

If AKI is very severe and isn't being controlled by drugs, how is it treated?

Answer 35

**Haemodialysis**

Question 36

In what situations would you put a patient with AKI on dialysis?

Answer 36

**Severely hyperkalaemic** **Severe metabolic acidosis** **Severely fluid overloaded** **Severely uraemic**