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Lucy Knox - Year 2.5 > 227 - Acute Renal Failure > Flashcards

227 - Acute Renal Failure Flashcards

1
Q

If this marker is high it suggests a poor prognosis / high mortality in AKI

A

High serum creatinine

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2
Q

What criteria is used for rating severity of AKI?

A

RIFLE criteria
GFR/Cr, urine output

Affected by age, DM, high BP, CCF

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3
Q

What extra-renal systems does AKI affect?

A

Pulmonary (pul oedema, ARDS, Leukocyte invasion, heamorrhage)

CNS (inflam reaction, altered conscious level, acidosis + electrolyte imbalence - confusion, convulsions, coma)

Cardiac (electrolyte imbalance, uraemic toxins, acidosis.. sympathetic NS - increase Bp, pericarditis, arrhythmias, Mi)

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4
Q

The causes of AKI are split into what 3 domains?

A

Pre-renal
Intrinsic
Post-renal

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5
Q

Describe how pre-renal issues can cause AKI

A

GFR reduced ↓ , due to haemodynamic disterbances - so causes ↓ globerular filtration.

No cellular injury

IF you reverse haemodynamic factors - should revert to ok

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6
Q

List 4 pre-renal causes of AKI

A

Intravascular vol depletion
↓ effective blood volume (burns)
Altered intrarenal haemodynamics (dehydration, sepsis)
3rd space sequestration (bowel obstruction)

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7
Q

List 3 intrinsic causes of AKI

A

Acute tubular necrosis (85%)
Radiocontrast nephropathy
Acute tubulo-interstial nephritis

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8
Q

What can cause acute tubular necrosis?

A

50% due to ischaemia - ↓bp, sepsis, cardiopulmonary arrest, bypass

35% nephrotoxic - drugs (aminoglycosides, radiocontrast, ACEi, NSAIDS) or pigment (Rhabdomyolysis, heamolysis)

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9
Q

How long does acute tubular necrosis last for?

A

Recover in 1 week due to proliferation and differentiation

Mortality linked with number of other failed organs

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10
Q

When might you be at risk of radiocontrast nephropathy?

A

When you need IV or intra-arterially injected contrast (special CT scans)

Not oral contrast or MRI contrast

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11
Q

Why can contrast cause nephropathy?

A

Contrast is hypertonic, so can induce transient vasodilation then constriction - can cause renal ischaemia.

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12
Q

How can you prevent contrast nephropathy?

A

Give lots of fluid - before and during

Use low osmolality contrast

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13
Q

What are the features of acute tubulo-interstitial nephritis?

A

An allergic reaction (so high mast cells and eosinophils)
Drug induced or infection mediated

  • Get fever, rash, arthralgia, eosinophila
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14
Q

What investigation can confirm acute tubulo-interstitial nephritis?

A

A biopsy - will show cellular infiltrates

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15
Q

What can cause post renal AKI?

A

An obstruction

- stone, necrosis, clot, TCC, stricture, fibrosis, tumour, aortic aneurysm

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16
Q

What are the features of urine in someone with post-renal AKI?

A

Dilute (can’t be concentrated as well)

Acidification is imparied - high blood acid and alkaline urine

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17
Q

What are 2 life threatening complications of AKI?

A

Metabolic acidosis

Hyperkaleamia

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18
Q

Describe metabolic acidosis in AKI

A

Can have a normal anion gap (bicarb is lost) or increased anion gap (acid is overproduced)

Get muscle weakness, altered mental state, kasmail breathing, high potassium and low BP

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19
Q

Describe how hyperkalemia occurs in AKI

A

When the pH of blood is low, H+ moves intracellularly
K+ moves out of cells to help keep the + balance
-> too much K+ in the blood

= muscle weakness, cardiac issues, big T waves (lots of pot lots of tea), wide QRS, bradycardia

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20
Q

How do you treat hyperkaleamia in AKI?

A

Treat cause
Give fluids
Correct acidosis
Protect heart - IV Ca Gluconate
Shift K+ back into cells - IV dextrose insulin
Reduce K+ absorption in GI tract - cation exchange resin

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21
Q

What is Rhabdomyolysis?

A

AKI caused by muscle necrosis releasing intracellular constituents. The AKI then causes electrolyte imbalance

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22
Q

How does Rhabdomyolysis cause AKI?

A

Haem pigment casts obstruct tubules - proximal tubular injury by heam iron

+ volume depetion due to swelling of damaged muscle

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23
Q

What are the signs and blood abnormalities of rhabdomyolysis?

A

Red/brown urine (as pigmented granular casts and supernatant in)

High serum enzymes - CK and LDH
Hifh K+, phosphate and uric acid
Low Ca (as goes to damaged muscles)

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24
Q

What could it mean if Ca was high in someone with known rhabdomyolysis?

A

They might be recovering, the excess Ca taken up by damaged muscles is released as it heals

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25
What can cause rhabdomyolysis?
Trauma - crush, struggle, immobilisation, compression Non-traumatic - marathon, hot weather, low K+, convulsions, low phosphate, alcohol, opiates, statins, cyclosporin, infections, DKA
26
How can you prevent rhabdomyolysis from occurring?
Fluid repletion Forced alkaline diuresis - if you increase the pH of urine then less myoglobin precipitates with tamm-horsfall protein - reduces free radical release - better Mannitol forced diuresis - osmotic diuretic. help flush out.
27
What is myeloma kidney?
A plasma disorder characterised by monoclonal immunoglobulin proliferation + marrow infiltration Causes heam abnormalities - anaemia Immune paresis Renal injury
28
How does myeloma kidney lead to renal injury?
Light chain Ig can be filtered by glomeruli and reabsorbed by the PCT, but they can block it - obstruction - AKI The light chain Igs also can bind to tamm-horsfall protein and precipitate into the tubules - obstruction and ? rupture - AKI
29
What signs are seen in myeloma kidney?
bone pain, weight loss, pallor, hyperviscosity - headaches, high BP, visual issues, convulsions - Renal failure, anaemia, high calcium and low platlets
30
What is the 1st line investigation for myeloma kidney?
SPEP electrophoresis - look at the gamma antibody peaks - will see an abnormal high peak
31
What investigations can be done to confirm myeloma kidney?
``` SPEP electrophoesis (1st line) immunofixation Free light chain assay Kidney biopsy Bone marrow biopsy? Xray - see punched out lesions ```
32
What are the treatment options for myeloma kidney?
You try to target each issue: - cast nephropathy - IV fluid, plasma exchange, or reduce production - chemo + steroids - hyperuricaemia - xanthine oxidase inhibitors, urate oxidase, fluid - hypercalcaemia - fluid + bisphosphonates - Hyper-viscosity - fluid, plasma exchange
33
Many drugs affect the kidneys. Which can cause damage by volume depletion?
Excessive laxatives Loop diuretics (furosemide, benetanide) NSAIDS
34
Many drugs affect the kidneys. Which can cause damage by altering renal haemodynamics?
ACE inhibitors A2RBs (angiotensin II receptor blockers - have vasodilator effects on efferent glomerular arterioles
35
Many drugs affect the kidneys. Which can cause damage by causing hypercalcaemia?
Calcium preparations | Vit D in a toxic dose
36
Many drugs affect the kidneys. Which can cause damage by hyperuricemia?
Chemo for bulky tumours
37
Many drugs affect the kidneys. Which can cause damage by causing hyperkalemia?
``` ACEi A2RBs Spironolactone amiloride (K+ sparing diuretic) NSAIDS ```
38
Many drugs affect the kidneys. Which can cause damage by causing hypokalemia?
``` loop diuretics Thiazide diuretics (bendroflumethiazide) ```
39
Many drugs affect the kidneys. Which can cause damage by increasing serum creatinine?
Trimethoprim Cimetridine - block Cr secretion
40
Many drugs affect the kidneys. Which can cause damage by irreversibly damaging the kidneys?
Aminoglycosides (gentamicin) | NSAIDS
41
Many drugs affect the kidneys. Which can cause damage by increasing CK - causing rhabdomyolysis?
Statins + Calcineurin inhibitors (cyclosporin) Particularly together
42
Renal failure affects drug processing. Which drug is affected by: volume depletion ?
Gentamicin - has a small vol of distribution, so if volume depletion, big effect
43
Renal failure affects drug processing. Which drug is affected by: altered protein binding?
Phenytoin - more free drug becomes available as proteins it usually binds to (albumin) are reduced, or other things (eg. urea) bind competitively to them.
44
Renal failure affects drug processing. Which drug is affected by: a reduction in drug metabolism?
Insulin - as kidney is place of phase I and II drug metabolism - so less broken down, increased serum conc
45
Renal failure affects drug processing. Which drug is affected by: reduced elimination
Renally excreted drugs - morphine | Increased half life - give lower dose
46
Renal failure affects drug processing. Which drug is affected by: uraemia
uraemia alters bodys response to drugs - increases sensitivities to CNS acting drugs (benzos) - increases GI bleed risk (NSAIDS) - increases hyperkalamia risk (K sparing diuretics - amiloride)
47
Renal failure affects drug processing. Which drug's effect is lost?
Nitrofurantoin - needs to be excreted into the urinary tract to work.
48
What can be checked in a urinalysis?
Chemical content Protein content Formed elements (Cells, RBCs, Fat, Casts) Crystals
49
How are casts formed in urine?
Formed in the DCT and collecting ducts by tubular microproteins (eg. tamm-horsfall)
50
What makes casts in urine abnormal?
When cells get trapped in the casts - eg. RBC casts due to glomerulonephritis - WBC casts - pyelonephritis or interstitial damage - Fatty casts - nephrotic syndrome
51
Name 4 crystals that can be found in urine?
Calcium oxalate Triple Phosphate Uric Acid Cystine
52
What shape are calcium oxalate crystals?
envelope | ? stones present?
53
What shape are triple phosphate crystals? Why do you get them?
Coffin lid - rectangle. in a UTI + alkaline urine
54
What do uric acid crystals suggest?
Gout, hyperuricaemia
55
What is GFR?
Glomerular filtration rate use a substance with constant levels that is only excrete by glomerular filtration - eg. urea or creatinine
56
Does urea give an over or underestimation of GFR?
Underestimates - some reabsorbed
57
Does creatinine over or underestimate GFR?
Overestimates. It is freely filtered, but tubular secretion is altered by drugs (eg. trimethoprim) If high muscle mass, more creatinine
58
What is eGFR?
estimated glomerular filtration rate Serum creatinine put into equation adjusted for age, wt, gender, race
59
What is hyponatremia?
Serum Na
60
What signs can you get with hyponatremia?
Asymptomatic? | Nausea, confusion, headache, lethargy, convulsions, coma.
61
What investigation findings would you find in someone with hyponatremia?
Low serum osmolality (usually) High urine osmolality If volume deplete, urinary Na 40
62
What are the 3 groups causes of hyponatremia fit into?
High ADH state Low ADH state High plasma osmolality
63
What high ADH states can cause hyponatremia?
Hypovolaemia - diarrhoea, vomiting, thiazide diuretics Hypervolaemia - heart failure, liver cirrhosis, SIADH, ecstacy, pregnancy
64
What LOW ADH states can cause hyponatremia?
renal failure Polydipsia Beer drinkers
65
What high osmolality states can cause hyponatremia?
renal failure hyperglycaemia mannitol therapy pseudohyponatramia
66
How can you treat hyponatremia?
Treat cause! fluid restriction and salt replacement if severe: vasopressin receptor antagonist (tolvaptam), loop diuretics
67
What can occur if you correct hyponatremia too quickly?
Osmotic demyelination syndrome 2-3 days later - dysarthria, dysphagia, paraparesis, confusion, behavioural issues.
68
Where is prorenin produced?
Juxtaglomerular cells
69
Where is renin stored?
Juxtaglomerular cells
70
Where is angiotensin I produced?
liver + kidney
71
Where is ACE produced?
Lung
72
Where is aldosterone produced?
Adrenal cortex
73
What prompts the release of renin?
Low renal blood flow | Increased sympathetic tone
74
What does angiotensin II cause?
efferent renal arteriolar contraction | Peripheral vasoconstriction
75
What does aldosterone do?
Activates Na/K pump in DCT - increases Na and water reabsoption

Lucy Knox - Year 2.5 (15 decks)

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