Nephrology non-BPT Flashcards

1
Q

What is the broad definition of an AKI?

A
  • abrupt drop in eGFR
  • acute reduction in UO
    *note these are markers of reduced function, not injury
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2
Q

In an AKI, which parameter is deranged first - SCr or eGFR?

A

There may be an acute drop in eGFR before the SCr increases

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3
Q

Describe the broad classifications of an AKI

A
  • pre-renal
  • renal
  • post-renal
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4
Q

Explain what a pre-renal AKI is

A

This definition describes a mechanism of reduced renal perfusion
- can be true volume depletion
- reduced effective blood volume (e.g. HF, cirrhosis) [due to overactivation of RAAS]

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5
Q

List 4 causes of pre-renal AKI

A
  • hypovolemia/true volume depletion (acute haemorrhage, diarrhoea, renal ECF depletion, fluid sequestration)
  • reduced effective arterial blood volume/hypervolemic state with low effective circulating volume (e.g. severe systolic HF with reduced EF, acutely decompensated liver disease with portal hypertentsion)
  • reduced SVR (e.g. sepsis)
  • alterations in renal vascular auto-regulation (e.g. afferent arteriole vasoconstriction caused by NSAIDs or contrast, renal artery stenosis)
    *note ARB/ACEi alter the kidneys ability to auto-regulate blood flow
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6
Q

Explain the mechanism of pre-renal AKI in hypovolemia

A

there is low perfusion pressure due to low arterial pressure

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7
Q

Explain the mechanism of pre-renal AKI in HFreF or abdominal compartment syndrome

A
  • perfusion pressure is the difference between arterial and venous pressure
  • A patient with HFpEF has elevated venous pressure, so this can lead to a low perfusion pressure
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8
Q

What are the 4 main components of the nephron?

A
  • glomerulus
  • tubules
  • interistium
  • vasculature
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9
Q

What are the two broad sub-types of acute tubular necrosis

A
  1. ishcaemic > extension of pre-renal
  2. toxins
    > endo-toxins = myoglobin, casts
    > exo-toxins = aminoglycosides, IV contrast, chemotherapy
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10
Q

What are renal casts?

A
  • cylindrical structures formed in the tubular lumen
  • matrix composed of Tamm-Horsfall mucoprotein
  • within the cast matrix are other elements (e.g. WBCs, RBCs, kidney cells, protein, fat) > this is how casts are defined
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11
Q

Where do renal casts tend to form?

A

They develop in the distal convoluted tubule or the collecting duct

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12
Q

How do you assess for renal casts?

A

Do a urinalysis

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13
Q

What is the clinical course of ATN?

A
  • injury pre-dates any changes to SCr
  • the SCr will platue once injury is established > if oliguria, consider need for RRT, if polyuria (that occurs at pletau phase) this usually heralds renal recovery
  • of note, polyuria occurs BEFORE improvement in SCr
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14
Q

What is a complication of ATN that can make a patient dialysis dependent?

A

cortical necrosis

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15
Q

What are the risk factors associated with contrast-associated AKI?

A
  • CKD
  • established CKD with proteinuria
  • Age
  • diabetes
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16
Q

List 2 ways a contrast-associated AKI can be prevented

A
  1. WH nephrotoxics
    > ACE/ARB
    > Frusemide
    > metformin
  2. Slow IVT prior to imaging
    *no benefit in NAC or sodium bicarb
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17
Q

What are the broad classifications of renal pathologies

A
  1. GN
  2. Acute tubular necrosis (e.g. contrast induced, THINK endotoxin vs. exotoxin)
  3. Acute intertistial nephritis
18
Q

How is a diagnosis of ATN made?

A
  • definitive diagnosis requires a biopsy
  • diffuse cellular infiltrate on biopsy
19
Q

List 4 causes of AIN

A
  1. Drug related (e.g. beta lactams, PPIs, NSAIDs, immunotherapy)
  2. Infection
  3. Immune-mediate (e.g. Sjogrens, Sarcoidosis, IgG4 disease)
  4. Idiopathic
20
Q

List 2 types of acute microvascular diseases that affect the kidney

A
  • thrombotic microangioapthy (includes spectrum of HUS-TTP)
  • DIC
  • catastrophic anti-phospholipid syndrome
  • systemic sclerosis
  • cholesterol emboli* (consider cardiac surgery, IABP, angiography)
21
Q

What are the structures post-renal that need to be considered in a post-renal AKI?

A
  • PUJ
  • ureter
  • bladder
  • prostate
  • urethra
    *Neurological - can be affected in MS, diabetes
22
Q

When assessing an AKI, what are the 3 key elements in the clinical work up?

A
  • history
  • medication review
  • volume assessment
23
Q

What kidney pathology might be suggestive of fragments on a blood film?

A
  • acute microvascular disease (renal cause)
  • consider associated presentation of anaemia, thrombocytopenia
24
Q

List 2 pathologies an eosinophilia may be suggestive of

A
  • AIN
  • Eosinophilic granulomatosis with polyangiitis (EGPA)
  • cholestrol emboli
25
Q

If a patient has a raised CK, what pathology does this suggest related to the kidney?

A

rhabdomyolysis

26
Q

What does a high urate suggest?

A

Tumour lysis syndrome

27
Q

What is the main purpose of a renal tract USS?

A

rule out obstruction

28
Q

If a urine dipstick is +ve for protein, what protein is this specifically?

A

albumin

29
Q

If a patient had microscopic haematuria on dipsitck, what might you be concerned about?

A
  • this is suggestive of myoglobin
  • need to consider rhabdomyolysis as a possible differential/issue in the presentation
30
Q

List two types of renal casts

A
  • hyaline casts
  • renal tubular epithelial casts // granular casts
31
Q

If you see hyaline casts of urine microscopy, what might this suggest?

A
  • reduced renal perfusion leading to sluggish flow
  • composed of uromodulin, formed in the loop of henle
  • NOT associated with tubular injury
  • may see this in exercise, dehydration
32
Q

If you see renal tubular eptihelial cells or casts what might this suggest

A
  • ischaemic injury > suggestive of ATN (but consider other cells present)
33
Q

What are granular casts and what might this be suggestive of?

A

Note granular casts = degraded lysosomes within RTECS, muddy brown appearance. THIS is suggestive of ATN

34
Q

What might White cell casts suggest of?

A
  • note rarely seen in isolation - often hard to distinguish from RTECs
  • could be AIN in the appropriate clinical context
35
Q

What finding in the urine is concerning for glomerular haemorrhage?

A
  • dysmorphic red cells
  • RBC casts
    > suggest proliferative glomerular lesion
36
Q

What are the uses of kidney USS?

A
  • obstruction (check for hydronephrosis)
  • reduced size, reduced cortical thickness, reduced echoginecity - could point to a chronic cause
  • doppler - consider vein thrombosis, stenosis, perfusion
37
Q

List 3 indications for a kidney biopsy

A
  • active urinary sediment
  • heavy proteinuria
  • aetiology unclear
  • confirm Dx - prognosis, response to treatment
  • exclude dual pathologies
38
Q

List 2 contraindications for a kidney biopsy

A
  • kidney failure
  • coagulopathy
  • bilateral cysts
  • uncontrolled HTN
  • hydronephrosis
  • UTI
39
Q

List the five indications for KRT

A
  1. Acidaemia
  2. Electrolyte disturbance
  3. Intoxicans (toxins)
  4. Fluid overload - refractory to treatment
  5. Uraemia - pericarditis, encephalopathy
40
Q
A