Acute Kidney Injury

Question 1

Define AKI

Answer 1

-> Reversible! renal dysfunction

Question 2

What is the KDIGO Classification of AKI ?

Answer 2

KDIGO Classification of AKI;

Increase in serum creatinine by ≥ 26 umol/L within 48 hrs

Increase in serum creatinine to ≥ 1.5 times baseline within the preceding 7 days

Urine volume < 0.5 ml/kg/hr for 6 hours

SO NOTICE; Changes in creatinine are a MASSIVE hint to kidney malfunction!

KDIGO stands for; Kidney disease, Improving global outcomes

Question 3

`Recognise the presenting symptoms of AKI

Answer 3

Depends on underlying CAUSE ;
Whether it is pre-renal, intrinsic, or post-renal

1. Oliguria/anuria (reduced or no urine output)

NOTE: abrupt anuria suggests post-renal obstruction

2. Nausea/vomiting
3. Dehydration
4. Confusion

Question 4

Recognise the signs of AKI on physical examination

Answer 4

1. Hypertension
2. Distended bladder
3. Dehydration - postural hypotension
4. Fluid overload (in heart failure, cirrhosis, nephrotic syndrome) - Raised JVP, pulmonary and peripheral oedema
5. Pallor, rash, bruising (vascular disease)

Question 5

Name Pre-Renal causes of AKI

Answer 5

Pre-Renal ( accounts for 90% of AKIs);

Hypovolaemia (e.g. haemorrhage, Diuresis, Diarrhoea, Dehydration, severe vomiting)

Heart failure

Cirrhosis

Nephrotic syndrome

Hypotension (e.g. shock, sepsis, anaphylaxis)

Renal hypoperfusion (e.g. NSAIDs, ACE inhibitors, ARBs, renal artery stenosis)

Question 6

Name intrinsic causes of AKI?

Answer 6

Glomerular - glomerulonephritis, haemolytic uraemic syndrome

Tubular - acute tubular necrosis

Interstitial - acute interstitial nephritis (e.g. NSAIDs, autoimmune)

Vasculitides (e.g. Wegener’s granulomatosis)

Eclampsia

Anything/ drug that wil cause nephrotoxicity so; Cisplatin, Vancomycin. So if the patient is on chemo… red flag -> intrinsic!

Question 7

Name causes of Post-Renal AKI?

Answer 7

(due to obstruction)

Calculi

Urethral stricture

Prostate hypertrophy or malignancy

Bladder tumour

Question 8

Name risk factors for AKI?

Answer 8

Age

Chronic kidney disease

Comorbidities (e.g. heart failure)

Sepsis

Hypovolaemia

Use of nephrotoxic medications ; chemotherapy, infections etc

Emergency surgery

Diabetes mellitus

Question 9

Summarise the epidemiology of AKI

Answer 9

15% of adults admitted to hospital will develop an AKI

Most common in the ELDERLY

Question 10

Identify appropriate investigations for AKI

Answer 10

All with aim to identify which subtype and then the casusative mechanism.

Bloods - all including clotting
Urinalysis - presence of blood indicates intrinsic cause?
Virology - hepatitis and HIV
Immunology
Ultrasound -Check for post-renal cause + Look for hydronephrosis

Imaging; cxr (if you find pulm oedema, then you can say, heart failure cause the aki)
CT KUB - look for renal calculi

Renal biopsy - if you have ruled out pre-renal and post renal causes and are certain it’s a renal parenchymal disease

Question 11

What very notable systemic disease causes aki?

Is it a pre-renal intrinsic or post-renal cause

Answer 11

SLE

It damages the glomerulus so it is an intrinsic cause

Question 12

What things do we look out for in immunology investigations in AKI? (considering the last card)

Answer 12

Serum immunoglobulins and protein electrophoresis - for multiple myeloma

Also check for Bence-Jones proteins in the urine

ANA - associated with SLE

Also check anti-dsDNA antibodies (high in active lupus)

Complement levels - low in active lupus

Anti-GBM antibodies - Goodpasture’s syndrome

Antistreptolysin-O antibodies - high after Streptococcal infection

Question 13

Generate a management plan for AKI

Answer 13

Treat the cause
• FOUR main components to management:
○ Protect patient from hyperkalaemia (calcium gluconate)
○ Optimise fluid balance
○ Stop nephrotoxic drugs
○ Consider for dialysis

• Monitor serum creatinine, sodium, potassium, calcium, phosphate and glucose
• Identify and treat infection
• Urgent relief of urinary tract obstruction
• Refer to nephrology if intrinsic renal disease is suspected

Question 14

When is Renal replacement therapy considered?

Answer 14

Renal Replacement Therapy (RRT) considered if:

○ Hyperkalaemia stubborn to medical management
○ Pulmonary oedema resistant to medical management
○ Severe metabolic acidaemia
○ Uraemic complications; seizure, coma, cardiac arrest, death

Question 15

Identify possible complications of AKI

Answer 15

• Pulmonary oedema
• Acidaemia
• Uraemia
• Hyperkalaemia; palpitations, numbness and tingling, weakness and tiredness etc
• Bleeding

Question 16

What is the prognosis of aki?

Answer 16

Inpatient mortality varies depending on cause and comorbidities
• Indicators of poor prognosis:
○ Age
○ Multiple organ failure
○ Oliguria
○ Hypotension
○ CKD
• Patients who develop AKI are at increased risk of developing CKD

Question 17

what are the 2 overaching ways AKI is diagnosed?

Answer 17

1. Fall in urine output

2. Rise in creatinine

Question 18

when does AKI progress to CKD?

Answer 18

Last for more than 3 months

Doesnt reverse

Question 19

mnemonic for most common causes of AKI?

Answer 19

S - sepsis
T - toxins eg amikacin
O - obstruction
P - parenchymal renal disease

Question 20

what counts as rhabdomyolysis?

Answer 20

creatinine 5x of upper limit of normal for age so eg 175x5 = 875