Acute Kidney Injury Flashcards by Ruksana Begum

neWhat are pre-renal causes of an AKI?

Hypovolaemia secondary to diarrhoea & vomiting, burns, major haemorrhage, shock, heart failure
Renal artery stenosis
Renal vein thrombosis

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5 examples of drugs should definitively be stopped during an AKI, as it may worsen it?

What drugs should also be stopped during an AKI, which will increase in toxicity but not necessarily worsen the AKI?

NSAIDs
Aminoglycosides
ACE Inhibitors
ARBS
Diuretics
Digoxin
Metformin
Lithium

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How can you prevent an AKI in patients about to have an investigation with contrast agent?

Give IV fluids before and after the investigation

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What is the acute management of patients with hyperkalaemia?

Calcium gluconate (stabilise cardiac membrane)
Insulin/dextrose infusion and salbutamol (short term)
calcium resonium (excretes K)
Loop diuretics / Dialysis (to remove K+)

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Is Aspirin safe to use during an AKI?

ONLY if low dose at 75mg OD

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What are the two main causes of Renal Artery Stenosis? What do they characteristically appear like on renal arteriography?

Atherosclerosis: Narrowing of renal artery proximal to aorta
Renal fibromuscular dysplasia: “String of beads” appearance of renal artery distal to aorta

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What abdominal examination finding is characteristic of renal artery stenosis?

Renal artery bruit

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What is the pathophysiology of Renal Artery Stenosis? What are the symptoms / signs of this condition?

Reduced perfusion to kidneys causes activation of RAAS, leading to a persistent HTN. There is also atrophy and fibrosis of the kidney

Symptoms: Persistent HTN, headaches, blurry vision, possible stroke / MI

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Oligouria is defined as what?

< 0.5 ml / kg / hr

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What is Stage 1, 2 and 3 Acute Kidney Injury defined as?

Stage 1:
1.5-2x increase in Creatinine
<0.5ml/kg/hr for 6-12 hours

Stage 2:
2-2.9x increase in Creatinine
<0.5ml/kg/hr for >12 hours

Stage 3:
3x increase in Creatinine
<0.3ml/kg.hr for >24 hours OR
Anuria for >12 hours

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What is the most common intra-renal AKI?

Acute Tubular Necrosis

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Acute Tubular Necrosis commonly affects which aspects of the kidneys?

Proximal Convoluted Tubule

Thick Ascending Limb

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What are the causes of Acute Tubular Necrosis? Toxic vs. Ischaemic

Ischaemic - hypotension (shock, sepsis)

Toxins - aminoglycosides, myoglobin (rhabdomyolysis), anti-freeze, radio-contrast dye, uric acid

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What is found in urinalysis of Acute Tubular Necrosis?

Muddy brown casts on urinalysis

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In someone with Pre-renal failure, what is the sodium concentration of the urine likely to be? Why?

< 20 mmol / L

Renal tubular function is preserved so reabsorption of sodium is preserved and in fact increased

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In someone with acute tubular necrosis, what is the sodium concentration of the urine likely to be? Why?

> 30 mmol / L

Renal tubular function is damaged hence reabsorption of sodium does not occur

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In someone with Pre-renal failure, what is the osmolality of the urine likely to be? Why?

High

Renal tubular function is preserved so reabsorption of water occurs

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In someone with acute tubular necrosis failure, what is the osmolality of the urine likely to be? Why?

Low

Renal tubular function is lost so rebabsorption of water does not occur hence is excreted in urine

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What is the affect of ACEI on the afferent / efferent arterioles?

Vasodilation of efferent arteriole

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What is the effect of NSAIDs on the afferent / efferent arterioles?

Vasoconstriction of afferent arteriole

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How does angiotensin II act to increase the filtration fraction in the kidney?

Vasoconstriction of efferent arteriole

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What is the MoA of spirinolactone?

Aldosterone antagonist / K+ sparring diuretic

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Is there a response to fluid challenge in Acute Tubular Necrosis and Pre-renal AKI?

Acute Tubular Necrosis - Yes

Pre-Renal AKI - No

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How do you calculate the anion gap?

Na + K - Cl - HCO3

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Which substance can be used to achieve the most accurate measurement of the glomerular filtration rate?

Inulin

What does the urine appear like in Pre-renal uraemia and Acute Tubular Necrosis?

Pre-renal Uraemia - Bland sediment | Acute tubular necrosis - Muddy brown casts

How can you prevent Tumour Lysis syndrome in cancer patients? In what cancer patients does it typically present?

Allopurinol Rasburicase Typically presents in Leukaemia / Lymphoma patients

What medications are capable of causing Acute Interstitial Nephritis?

NSAIDs Penicillin Diuretics

What is Acute Interstitial Nephritis? What are the symptoms

Inflammation of the interstitium, caused by Eosinophil and Neutrophil infiltration. "allergic" presentation: eosinophilia, FEVER, RASH, oliguria

All diabetic patients require annual screening for their kidneys by what test?

Albumin:creatinine ratio (ACR) in early morning specimens

What are the clinical features of NephrOtic syndrome?

PrOteinuria HypOalbuminaemia Oedema Hyperlipidaemia (Oh so fat)

If Nephrotic syndrome is diagnosed in children, what is the assumed condition?

Minimal change disease

State 5 Nephrotic syndromes

Minimal change disease Membranous nephropathy Focal segmental glomerulosclerosis Amyloidosis Diabetic nephropathy

If a child is diagnosed with Minimal Change Disease but is unresponsive for steroids, what is the next course of action?

Kidney biopsy

What is the general management for Nephrotic Syndrome?

- Coticosteroids - Renal biopsy to diagnose underlying cause and if no response to steroids - Treat hypertension with ACEI / ARB if appropriate - Treat underlying cause

In Minimal Change Disease, what is the characteristic finding on histology?

Fusion of podocyte foot processes

In Minimal Change Disease, what is the treatment?

Corticosteroids

In Minimal Change Disease, what is it associated with?

Hodgkin's Lymphoma, NSAID use

In Membranous Nephropathy, what is the characteristic finding on histology?

Basement membrane thickening due to IgG complex deposition

In Membranous Nephropathy, what is the treatment?

1/3 -> resolve by themselves 1/3 -> require cytotoxic drugs 1/3 -> lead to CKD

Why is clotting impaired in Nephrotic Syndrome?

Loss of antithrombin III and plasminogen in urine

What are the clinical features of Nephritic Syndrome?

- Hypertension - Haematuria - Oligouria - Proteinuria

Give three examples of Nephritic syndromes

IgA nephropathy Alport syndrome Rapidly progressive GN

What are the clinical features of IgA nephropathy and Post-streptococcal glomerulonephritis?

IgA - followed by a URTI few days ago | PSGN - followed by a URTI few weeks ago

Give examples of 2 conditions which have both Nephrotic and Nephritic features

Post-strep GN Membranoproliferative GN

Which Membranoproliferative glomerulonephritis is associated with Hepatitis C?

Type 1

What is the most common Nephrotic syndrome in adults?

Focal Segmental Glomerulosclerosis

Haemolytic uraemic syndrome is commonly caused by what?

E. Coli 0157:H7

What is the first-line treatment for Rhabdomyolysis?

0.9% NaCl IV

What is the most common cause of Acute Kidney Injury?

Acute Tubular Necrosis

ACUTE TUBULAR NECROSIS 1. What are some causes of Acute Tubular Necrosis? 2. What is classically seen in ATN on urinalysis? 3. What is the Urinary Sodium or Urinary Osmolality for ATN?

1. Ischaemia (Shock, sepsis) Toxins (Aminoglycosides, Rhabdomyolysis, Radiocontrast dye, Uric acid) 2. Brown muddy casts 3. High urinary sodium, low urine osmolality

ACUTE INTERSTITIAL NEPHRITIS 1. What is it? 2. What type of hypersensitivity reaction is it? 3. What typically causes it? 4. What are the classic features? 5. What is seen on urinalysis? 6. How is it managed?

1. A hypersensitivity reaction of inflammation of the interstitium (space between cells and tubules in kidneys) 2. Type 1 or 4 Hypersensitivity reaction 3. NSAIDs, penicillin, diuretics 4. FEVER, EOSINOPHILIA, RASH (allergic picture) 5. Sterile pyuria, WC casts 6. Treat underlying cause, steroids to reduce inflammation

RHABDOMYOLYSIS 1. What is it? 2. What are the symptoms? 3. What are the investigations? 4. What is the management?

1. When skeletal muscle tissue breaks down, releasing the products into the blood 2. Muscle aches, fatigue, confusion, red urine 3. Elevated creatine kinase, myoglobinuria, U&Es (hyperkalaemia), 12-lead ECG 4. IV Fluids, IV Sodium bicarbonate, IV mannitol and correct the hyperkalaemia

DIABETIC NEPHROPATHY 1. What is it? 2. What is the main feature on urinalysis? 3. How are patients screened for it? 4. How is it managed?

1. The most common cause of CKD in UK 2. Proteinuria 3. Early morning sample of albumin:creatitine ratio 4. Monitor HTN, have good glycaemic control, and ACEI

Why are ACEi not classed as nephrotoxic medications?

They are protective of kidneys long term and do not cause AKI but they worsen it as they reduce the filtration pressure

What is the definition of Stage 1, 2, 3 AKI?

Stage 1: <0.5ml / kg / hr for 6-12 hours Stage 2: <0.5ml / kg / hr for >12 hours Stage 3: <0.3ml / kg / hr for >24 hours or anuria for 12 hours

Causes of pre renal AKI?

Pre-renal: renal artery stenosis, dehydration, hypotension, heart failure

What are the risk factors of an AKI?

Acute illness i.e. infection, surgical operation, CKD, heart failure, diabetes, old age, cognitive impairment, recent contrast agent, previous AKI, drugs (NSAIDs, ACEIs, ARBs, aminoglycosides, diuretics)

What are the investigations for an AKI?

Urinalysis for leukocytes, nitrites (infection) blood, protein (nephritis) U&Es Renal US if ?obstruction or unknown cause

How do you manage an AKI?

Fluid rehydration, especially for pre-renal AKIs. Stop any nephrotoxic medications i.e. ACEIs, ARBs, NSAIDs, aminoglycosides. Relieve post-renal obstructions i.e. catheterising

How to manage hyperkalaemia in AKI?

First line: Calcium gluconate insulin / dextrose infusion salbutamol Calcium resonium

What are complications of patients with AKI?

Hyperkalaemia Uraemia -> encephalopathy, pericarditis Metabolic acidosis FLuid overload, failure, pulmonary oedema

Causes of renal AKI

Renal: Acute tubular necrosis, acute interstitial nephritis, rhabdomyolysis, glomerulonephritis

Causes of post renal AKI

Post-renal: Kidney stones, BPH / Prostate cancer, urethral stricture, abdominal / pelvic mass