AKI and Background Flashcards

0
Q

Define AKI (2)

A

Impairment of renal function over days or weeks causing an abrupt sustained rise in serum urea and creatinine and oliguria.

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1
Q

What functions of the kidney can be affected by AKI? (5)

Clue: ABCDE

A
Acid-base balance
Bp control
Control of water and solute homeostasis
vitamin D hydroxylation
EPO production
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2
Q

Define CKD. (1)

A

Long standing and usually progressive impairment of renal function.

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4
Q

What are the 3 classifications of the causes of AKI. (3)

Give examples of each. (2 each)

A

Pre-renal (decreased perfusion):

  • shock (hypovolaeimc, cardiogenic, septic)
  • hepatorenal syndrome (liver failure)
  • renal artery stenosis

Renal:

  • ATN (ischaemia, paracetamol, aminoglycosides, NSAIDs, ACEi, Lithium, amphotericin B)
  • Acute GN
  • Acute interstitial nephritis (NSAIDs, penicillin, sulphonamides, leptospirosis)
  • Small or large vessel obstruction (cholesterol emboli, vasculitis)
  • Light chain, urate or pigment nephropathy
Post-renal (obstruction): 
-Stone
-Tumour (pelvic, prostate, bladder)
-Blood clots
Retroperitoneal fibrosis
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5
Q

What are the causes of pre-renal AKI? (4)

A

Impaired perfusion of kidneys caused by…

  • Hypovolaemia
  • Hypotension
  • Impaired cardiac pump efficiency
  • Vascular disease limiting renal blood flow
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6
Q

How does the kidney maintain GFR despite variation in renal perfusion? (2)

A

“Autoregulation”
Intrarenal production of prostaglandins and angiotensin II.

In severe and prolonged hypoperfusion there is eventually a drop in GFR.. pre-renal failure.

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7
Q

What investigations can be used to differentiate between prerenal and renal causes of AKI? (3)

A
  • Urine specific gravity - measure of concentrating ability
  • Urine osmolality - measure of concentrating ability
  • Urine sodium - low in avid tubular reabsorption but increased by diuretics and dopamine
  • Fractional excretion of sodium - ratio of sodium clearance to creatinine clearance
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8
Q

What is the management of prerenal failure? (2)

A

If due to hypovolaemia or hypotension:
-Replace with blood if haemorrhage or crystalloid if d&v to prevent development of ischaemic renal injury.

If due to cardiac pump insufficiency or occlusion of renal vasculature:
-Correct underlying cause.

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9
Q

What is the basic cause of postrenal uraemia? (1)

A

Total urinary tract obstruction

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10
Q

How are patients with AKI investigated for postrenal causes? (4)

A

Abdo exam and USS: Enlarged, palpable kidneys/bladder
DRE: Large prostate
Vaginal exam: Pelvic masses
Renal USS: Hydronephrosis and dilated ureters
Place catheter or flush catheter: Rule out bladder outflow obstruction

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11
Q

How to treat post renal obstruction? (1)

A

Treat cause, ie remove obstruction or relieve pressure by urethral/suprapubic catheter or percutaneous nephrostomy.

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11
Q

Name 5 causes of ATN. (5)

A
Haemorrhage
Burns
D&V
Diuretics
MI
CCF
Haemaglobinaemia eg malaria Falciparum
Drugs: aminoglycosides, nsaids, acei
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12
Q

Name some renal causes of AKI. (3)

A
  • ATN* as a result of renal ischaemia or direct renal toxins
  • Acute interstitial nephritis
  • Acute glomerulonephritis
  • Renal vasculature diseases eg vasculitis, accelerated hypertension, cholesterol embolism, haemolytic uraemic syndrome, thrombotic thrombocytopaenic purpura
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14
Q

What are the symptoms of AKI? (2)

A
Early- asymptomatic
Later: 
-Oliguria
-Symptoms of uraemia
   Weakness, fatigue, anorexia, n&v, ?pruritis, ?bruising, confusion, seizures, coma
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15
Q

What are the biochemical abnormalities that may be seen in AKI? (5)

A

Hyperkalaemia
Metabolic acidosis (unless loss of H+ by vomiting)
Hyponatraemia (water overload)
Hypocalcaemia (reduced hydroxylation of vit D)
Hyperphosphataemia (phosphate retention)

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15
Q

What investigations would you perform in AKI? (5)

A

Bedside:
-Urine dipstick, culture and microscopy: infection or GN
-Urinary electrolytes: exclude prerenal element
Bloods:
-FBC (anaemia or v. high ESR = myeloma or vasculitis)
-Blood cultures (exclude infection)
-Serum Ca, phosphate and uric acid
Radiology:
-renal USS (exclude obstruction and assess renal size)
-abdo CT (diagnose retroperitoneal fibrosis)
Special: biopsy

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16
Q

Why can AKI predispose to sepsis?

A

Impaired immune defence (uraemia and malnutrition)

Instrumentation (dialysis, vascular lines and urinary catheters)

17
Q

What are the indications for dialysis in AKI? (5)

A
  • Progressive uraemia with encephalopathy or pericarditis
  • Severe biochemical derangement
  • Hyperkalaemia not controlled by conservative means
  • Pulmonary oedema
  • Severe metabolic acidosis, pH<7.1
  • To remove drugs causing the AKI e.g. gentamicin, lithium or severe aspirin overdose
19
Q

Why can AKI predispose to sepsis? (2)

A

Impaired immune defence (uraemia and malnutrition)

Instrumentation (dialysis, vascular lines and urinary catheters)

20
Q

Which part of kidney can regenerate from AKI? (1)

A

Tubules regenerate.

Cortex heals with scar tissue.

21
Q

What vertebra do the kidneys lie between? (1)

Which kidney is positioned higher? (1)

A

T12-L3

Right kidney is slightly higher than the left.

22
Q

How many nephrons are in each kidney? (1)

A

1 million, each with its own afferent arteriole.

23
Q

Name 3 symptoms one should ask about in a history of a renal patient. (3)

A
Dysuria
Haematuria
Frequency
Retention of urine
Alteration of urine volume e.g. polyuria or oligouria

Lethargy, anorexia, pruritis (CKD)

24
Q

Name 3 differentials for a adult women presenting with dysuria. (3)

A

UTI
Chlamydia
Neisseria Gonorrhoeae
candida albicans

25
Q

Define polyuria. (1)

A

Urine output >2.5-3L in 24 hours

26
Q

Name 3 differentials for polyuria. (3)

A

Hyperglycaemia (DM)
Diabetes insipidus
Polydipsia
CKD

27
Q

What does prolonged oliguria suggest? (2)

A

AKI or urinary tract obstruction.

28
Q

Mrs Duncan has been on the ward following a total hip replacement and since her surgery has become oliguric.
What will be your 3 management steps? (3)

A
  1. Exclude obstruction:
    In bladder- discomfort with desire to micturate, palpable bladder. Pass catheter or flush catheter if in situ.
    Ureteric- is painless, USS to exclude pelvicalyceal dilatation.
  2. Assess for hypovolaemia: BP, pulse, JVP, urinary electrolytes. try fluid challenge if hypovolaemic.
  3. Management of established AKI
29
Q

What is a fluid challenge? (2)

A

Give 500ml saline 0.9% IV over 30 minutes and monitor urine output response.

30
Q

Give 3 differentials of loin pain. (3)

A

Acute pyelonephritis, upper urinary tract obstruction, occlusion of renal artery (thrombosis or emboli), calculus (acute severe radiating), cystic kidney and renal tumours (chronic pain)

31
Q

Why is creatinine a better guide to GFR than urea? (2)

A

Urea is affected by diet, GI bleeding, surgery, trauma, infection.
Creatinine is more consistent, depending on age, sex and muscle mass.

32
Q

Name 3 things that urine dipsticks test for? (3)

A
Protein (albumin)
Blood
Glucose
Ketones
Bilirubin
Urobilinogen
Nitrites
Leucocyte elastase
pH
33
Q

Name 3 causes of proteinuria. (3)

A

Glomerular: increased permeability: glomerulopathy
Tubular: decreased reabsorption: Fanconi’s
Overflow: plasma proteins produced in excess: multiple myeloma
Physiological: Increased renal haemodynamics: illness, fever, intense activity, upright posture

34
Q

How can proteinuria be quantified? (2)

A

PCR: urinary protein : urinary creatinine ratio
ACR: urinary albumin : urinary creatinine ratio

35
Q

What is normal urinary protein loss per day? (1)

What is nephrotic range of protein loss per day? (1)

A

3.5g per day

36
Q

What are the two types of haematuria? (2)

A

Macroscopic

Microscopic

37
Q
Gordon has haematuria. 
Where is the cause of bleeding if haematuria is visible;
a) at the beginning
b) at the end
c) even discolouration throughout? (3)
A

a) urethral disease
b) prostate or bladder base
c) bladder or above

38
Q

Name 5 differentials for haematuria. (5)

A

Haematology: Bleeding disorder
Renal: Papillary necrosis, tubulointerstitial nephritis, Cysts, TB, glomerulonephritis, trauma, renal carcinoma, stone
Ureter: Ureteric neoplasms or stones
Bladder: Stone, parasites, carcinoma, infection
Prostate: Benign prostatic hyperplasia, carcinoma
Urethra: Trauma, infection, tumour
Gynae: contamination during menstruation

39
Q

How can ACE inhibitors and NSAIDs precipitate AKI? (2)

A

Maintenance of a normal GFR when the systemic blood pressure is low relies on infrarenal production of prostaglandins and angiotensin II.
As ACEi and NSAIDs block the production of these two molecules, AKI can ensue.

40
Q

What are the symptoms of uraemia? (4)

A

Weakness, fatigue, anorexia, nausea, vomiting.

Followed by mental confusion, seizures and coma.

41
Q

How can a patient’s response to treatment be measured in AKI? (1)

A

Urea and Creatinine

42
Q

What are the purposes of investigations in AKI? (3)

A
  1. Differentiate acute from chronic kidney disease
  2. Document degree of renal impairment and determine baseline values to monitor response to treatment.
  3. Determine whether pre-renal, renal or post-renal causation (or more specific cause)