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Flashcards in Week 227 - Acute Renal Injury Deck (110):
1

Week 227 - Acute Renal Injury: What are the pre-renal causes of Acute Renal Failure?

• Due to disturbance in renal blood supply.
- E.g. Hypotension/Hypovolaemia, Cirrhosis, renal artery stenosis.

2

Week 227 - Acute Renal Injury: What are the renal/intrinsic causes of Acute Renal Failure?

• Damage to the parenchyma of the kidney itself.
- E.g. glomerulonephritis, acute tubular necrosis, acute interstitial nephritis.

3

Week 227 - Acute Renal Injury: What are the post-renal causes of Acute Renal Failure?

• Usually a consequence of urinary tract obstruction.
- E.g. BPH, renal stones, obstructed urinary catheter, bladder stones or malignancy.

4

Week 227 - Acute Renal Injury: What is Rhabdomyolysis?

• Skeletal muscle breakdown secondary to injury.
• For example following strenuous exercise, trauma or infection.
• Leading to the leakage of potentially toxic intracellular contents into the blood stream,

5

Week 227 - Acute Renal Injury: What is the 'triad' of Rhabdomyolysis?

1) Myalgia
2) Generalized weakness
3) Tea-coloured urine.

6

Week 227 - Acute Renal Injury: How can rhabdomyolysis cause acute renal failure?

• Obstruction with haem pigment casts.
• Proximal tubular injury by haem iron.
• Volume depletion (Damaged muscles can accumulate fluid over time, causing a reduction in circulating volume).

7

Week 227 - Acute Renal Injury: What are some of the non-traumatic causes of rhabdomyolysis?

• Marathon runners
• Hot weather
• Hypokalaemia
• Prolonged convulsions
• Metabolic myopathy
• Malignant hyperthermia
• Hypothermia

8

Week 227 - Acute Renal Injury: Which drugs can cause rhabdomyolysis?

• Alcohol, opiates, statins, colchicine, cyclosporin.

9

Week 227 - Acute Renal Injury: How is rhabdomyolysis induced AKI diagnosed?

• History
• Red to brown urine
• Elevated serum enzyme level - CK, LDH
• Electrolyte abnormalities.

10

Week 227 - Acute Renal Injury: Which electrolyte abnormalities do you get with rhabdomyolysis induced AKI?

• Hyperkalaemia
• Hyperphosphatamia
• Hyperuricaemia
• Hypocalcaemia (However, you will get hypercalcaemia in the recovery phase)

11

Week 227 - Acute Renal Injury: What are the preventative options for stopping rhabdomyolysis causing AKI?

• Fluid repletion - Improve renal perfusion, washout obstructing casts.
• Forced alkaline diuresis - Using Sodium Bicarbonate - Reduces myoglobin precipitation.
• Forced diuresis - Using Mannitol.

12

Week 227 - Acute Renal Injury: What is Mannitol used for and what are the complications of its use?

• Osmotic diuretic - Forced diuresis - Free radical scavenger.
• Can cause hypernatraemia.
• And can cause increased plasma osmolality and volume expansion in those with poor renal function.

13

Week 227 - Acute Renal Injury: What are urinary casts?

• They are cylindrical structures formed in the distal convoluted tubules.
• They are primarily made from tubular mucoprotein (Tamm-Horsfall protein).
• The presence of the them in urine microscopy can signify a number of disease states.

14

Week 227 - Acute Renal Injury: The presence of a red blood cell cast can indicate which disease state?

• Patients with glomerular haematuria.
- E.g. glomerulonephritis.

15

Week 227 - Acute Renal Injury: The presence of a white blood cell cast indicates which disease state?

• Acute pyelonephritis or interstitial nephritis.

16

Week 227 - Acute Renal Injury: The presence of a fatty cast indicates the presence of which disease state?

• Lipiduria
- E.g. nephrotic syndrome.

17

Week 227 - Acute Renal Injury: What is nephrotic syndrome?

• This is where the permeability of the walls of the glomerulus is increased resulting in proteinuria.

18

Week 227 - Acute Renal Injury: The presence of a pigmented cast indicates the presence of which disease states?

• Haemoglobinuria
• Myoglobinuria

19

Week 227 - Acute Renal Injury: What is the shape of calcium oxalate crystals?

Square, enveloped shapes.

20

Week 227 - Acute Renal Injury: What is the shape of a triple phosphate crystal? What does it indicate?

• Coffin lid shape.
• Alkaline urine
• Proteus UTI

21

Week 227 - Acute Renal Injury: What shape are uric acid crystals? What does their presence indicate?

• Diamond shaped.
• Hyperuricaemia.

22

Week 227 - Acute Renal Injury: What is the definition of clearance (In terms of measuring renal function)?

• Volume of plasma cleared of substance in unit time.
• Measured as the volume of indicator removed from plasma divided by average plasma concentration during a given time.

23

Week 227 - Acute Renal Injury: What are the limitations of using creatinine clearance to measure renal function?

• Difficult, time consuming.
• Inaccurate urine collections.
• Diurnal and day-to-day variations in creatinine clearance.
• Not adjusted for age,gender,race etc.

24

Week 227 - Acute Renal Injury: What is the eGFR, clinical findings and treatment of stage one of CKD?

• Normal kidney function but urine findings or structural abnormalities point to kidney disease.
• eGFR 90+
• Observation, control of BP.

25

Week 227 - Acute Renal Injury: What is the eGFR, clinical findings and treatment of stage two of CKD?

• Mildly reduced kidney function and urine/structural/genetic findings point to kidney disease.
• eGFR 60-89
• Observation, control of BP, Control of risk factors.

26

Week 227 - Acute Renal Injury: What is the eGFR, clinical findings and treatment of stage three of CKD?

• Moderately reduced kidney functions.
• eGFR 30-59
• Observation, control of BP, Control of risk factors.

27

Week 227 - Acute Renal Injury: What is the eGFR, clinical findings and treatment of stage four of CKD?

• Severely reduced kidney function.
• eGFR 15-29
• Planning for end stage renal failure.

28

Week 227 - Acute Renal Injury: What is the eGFR, clinical findings and treatment of stage five of CKD?

• Very severe, or end stage renal failure.
• eGFR

29

Week 227 - Acute Renal Injury: What is the RIFLE criteria?

• Categorizes the degree of renal failure into,
- Risk
- Injury
- Failure
- Loss
-End stage kidney disease

30

Week 227 - Acute Renal Injury: What are the pulmonary complications of acute kidney injury?

• Fluid overload > Pulmonary oedema
• Increased pulmonary vascular permeability.
• Leucocyte migration
• Pulmonary haemorrhage
• Infection
• ARDS

31

Week 227 - Acute Renal Injury: What are the CNS complications of acute kidney injury?

• Inflammatory reaction
• Acidosis
• Electrolyte imbalance
• Confusion
• Convulsions
• Altered conscious levels
• Coma

32

Week 227 - Acute Renal Injury: What are the cardiac complications of acute kidney injury?

• Acidosis
• Sympathetic overactivity
• Hypertension
• Pericarditis
• Arrhythmia
• Cardiac hypertrophy
• Heart Failure
• MI

33

Week 227 - Acute Renal Injury: What characterises pre-renal acute renal failure?

• Intravascular volume depletion.
• Decreased effective blood volume.
• Altered intrarenal haemodynamics
- Afferent vasoconstriction
- Efferent vasodilation

34

Week 227 - Acute Renal Injury: What are the characteristics of intrinsic acute renal failure?

• Acute tubular necrosis
• Acute interstitial nephritis
• Acute glomerulonephritis
• Acute vascular syndromes

35

Week 227 - Acute Renal Injury: What is third space sequestration?

• Accumulation of fluid in the third space - i.e. the transcellular compartment.
• Can be a result of bowel obstruction, peritonitis, pancreatitis, ascites.
• Can result in hypovolaemia resulting in acute renal injury.

36

Week 227 - Acute Renal Injury: How can third space sequestration clinically manifest?

• Respiratory compromise.
• Decreased cardiac output.
• Intestinal ischaemia.
• Hepatic dysfunction.
• Oliguric renal failure - Oliguria occurs when intra-abdominal pressure exceeds 15mmHg, with anuria developing when the pressure exceeds >30mmHg.

37

Week 227 - Acute Renal Injury: How is third space sequestration treated?

• Abdominal decompression.
- Paracentesis
- Surgical decompression

38

Week 227 - Acute Renal Injury: What is the normal GFR?

120 ml/min, >7L/hr

39

Week 227 - Acute Renal Injury: In cases of partial post-renal obstruction, what dysfunction does the distal tubule experience in terms of concentration and acid/base balance?

• Reduced concentration - Polyuria
• Loss of acidification resulting in a metabolic acidosis.

40

Week 227 - Acute Renal Injury: In terms of history and examination, what may indicate post-renal failure?

• History - Colic, stone disease, polyuria, nocturia, Haematuria, DM, Neurological condition.

• Examination - Palpable bladder, bladder scan, post-micturition residual urine, KUB ultrasound scan.

41

Week 227 - Acute Renal Injury: What type of acute kidney injury is acute tubular necrosis?

Intrinsic

42

Week 227 - Acute Renal Injury: What are some of the causes of acute tubular necrosis?

• Ischaemic - e.g. Hypotension, Sepsis.

• Nephrotoxic - Drug-induced e.g. Aminoglycosides, cisplatinum, paracetamol.
- Pigment nephropathy - Intravascular haemolysis, rhabdomyolysis.

43

Week 227 - Acute Renal Injury: What is the most common form of intrinsic acute renal failure?

• Acute Tubular Necrosis (ATN)

44

Week 227 - Acute Renal Injury: What is the mortality rate of uncomplicated ATN?

7%-23%

45

Week 227 - Acute Renal Injury: 50% of radiocontrast nephropathies develop after which procedures?

• Cardiac diagnostic and interventional procedures.

46

Week 227 - Acute Renal Injury: What are the risk factors for developing radiocontrast nephropathy?

• Pre-existing renal disease.
• DM
• Hypertension
• ACEI, NSAIDs
• Volume depletion
• Large volume of contrast

47

Week 227 - Acute Renal Injury: How can the risk of developing radiocontrast nephropathy be reduced?

• Low-osmolality contrast media.
• IV fluid

(Antioxidants, N acetyl cysteine, diuretics, IV sodium bicarbonate)

48

Week 227 - Acute Renal Injury: What are the causes of Acute tubulo-interstitial nephritis?

• Drug-induced - Penicillins, cephalosporins, sulfonamides, rifampicin, frusemide, NSAIDs.

• Infection - Bacterial, viral, rickettsial disease, tuberculosis.

49

Week 227 - Acute Renal Injury: What (from history, signs, examination, investigations) would lead you to consider acute tubulo-interstitial necrosis?

• History - Exposure, drug/infection.
• Fever
• Rash
• Arthralgia
• Oesinophilia
• Biopsy - cellular infiltrate.

50

Week 227 - Acute Renal Injury: How do you treat acute tubulo-interstitial necrosis?

• Withdraw the offending agent/ treat infection.
• Steroids.

• Has a very good outcome.

51

Week 227 - Acute Renal Injury: What are the three life-threatening complications of acute kidney injury?

• Metabolic Acidosis
• Hyperkalaemia
• Acute pulmonary oedema

52

Week 227 - Acute Renal Injury: How is the serum anion gap calculated?

AG = Cations - Anions
AG= Na + K - Cl - HCO3

53

Week 227 - Acute Renal Injury: What occurs during normal anion gap metabolic acidosis? What causes it?

• Acidosis is due to loss of bicarbonate, this is replaced by chloride resulting in a normal anion gap.
• Can be caused by diarrhoea, renal tubular acidosis.

54

Week 227 - Acute Renal Injury: What occurs to give an increased anion gap metabolic acidosis? What can cause it?

• Increased acid production with anion other than Cl.
• Can be caused by lactic acidosis, DKA, Renal failure, Methanol, Ethylene Glycol.

55

Week 227 - Acute Renal Injury: What is the clinical effect of a metabolic acidosis?

• Muscle weakness
• Altered mental state
• Kussmaul breathing
• Hyperkalaemia
• Hypotension

56

Week 227 - Acute Renal Injury: What is Kussmaul breathing?

• Deep and labored breathing.
• Associated with severe metabolic acidosis.

57

Week 227 - Acute Renal Injury: What is the treatment of metabolic acidosis?

• Treat the cause!
• Volume expansion
• IV sodium bicarbonate (Only in severe acidosis

58

Week 227 - Acute Renal Injury: What are the effects of hyperkalaemia?

• Muscle weakness
• Constipation
• Cardiac effects
• ECG changes - loss of P wave, AV block, bradycardia, V tachycardia, asystole.

59

Week 227 - Acute Renal Injury: What are the ECG changes associated with hyperkalaemia?

• Loss of p waves.
• AV block
• Bradycardia
• V tachycardia
• Asystole

60

Week 227 - Acute Renal Injury: What are the treatment options for hyperkalaemia?

• Treatment of the cause!
• IV fluid
• Bicarbonate therapy
• IV dextrose insulin - shifts K into intracellular.

61

Week 227 - Acute Renal Injury: What are the four main mechanisms for maintaining blood pressure?

1) Sympathetic stimulation.
2) Stimulation of renin-angiotensin system.
3) Mechanisms to retain fluid - Thirst + ADH
4) Retaining sodium

62

Week 227 - Acute Renal Injury: How does sympathetic activation maintain blood pressure?

1) Tachycardia and increased cardiac contractility
2) Peripheral vasoconstriction > Diverting blood to vital organs.

63

Week 227 - Acute Renal Injury: What are the key steps in the renin-angiotensin pathway? Pro-Renin > Aldosterone

Pro-renin > Renin converts Angiotensinogen > Angiotensin I > Angiotensin II (Angiotensin II has a number of effects)

64

Week 227 - Acute Renal Injury: ACE is responsible for what step in the renin-angiotensin system?

Conversion of angiotensin I into angiotensin II.

65

Week 227 - Acute Renal Injury: What are the 5 effects of angiotensin II?

1) Increases sympathetic activity.
2) Tubular Na, Cl reabsorption and K excretion, H20 retention.
3) Stimulates adrenal cortex to release aldosterone.
4) Arteriolar constriction.
5) Stimulates posterior pituitary gland to increase ADH secretion.

66

Week 227 - Acute Renal Injury: Where are the juxtaglomerular cells?

Afferent arterioles.

67

Week 227 - Acute Renal Injury: Where is the macula densa?

Distal tubular cells.

68

Week 227 - Acute Renal Injury: What occurs in the kidney in response to a low GFR?

• You will get decreased tubular flow rate. Results in,
• Decreased Cl delivery to macular densa. The Macula densa then,
• Decreases afferent arteriolar resistance, which,
• Increases renal blood flow, which
• Increases glomerular pressure, causing an
• Increase in tubular flow.

69

Week 227 - Acute Renal Injury: How does the kidney respond to high BP?

Afferent arteriolar constriction in order to protect the glomeruli.

70

Week 227 - Acute Renal Injury: How does the kidney respond to low BP?

• Barostretch receptors are triggered causing afferent dilation and an increase in angiotensin II causing efferent constriction and an increase in glomerular pressure.

71

Week 227 - Acute Renal Injury: How does a high GFR affect the kidney?

• Rise in tubular flow, causing an increased delivery of Na and Cl to the macula densa, there is then afferent constriction to reduce glomerular pressure.

72

Week 227 - Acute Renal Injury: What effect does angiotensin II have on the afferent/efferent arterioles?

Constricts both. However efferent is already narrower, so has the net effect of increasing glomerular pressure.

73

Week 227 - Acute Renal Injury: What can cause the dilation of the afferent arterioles?

• Prostaglandins
• Ca channel blockers
• Decreased tubular flow rate.

74

Week 227 - Acute Renal Injury: What can cause constriction of the afferent arterioles?

• Increased barostretch
• Increased tubular flow rate
• Increased sympathertic activity
• NSAIDs
• Angiotensin II

75

Week 227 - Acute Renal Injury: What is the effect of volume depletion in the kidney?

• Decreased barostretch > Afferent dilation.
• Increased sympathetic tone > Increased renin.
• Increase in Renin and ATII > Rise in GFR
• Increase of Na absorption in proximal convoluted tubules due to ATII.
• Decreased delivery of NaCl to macula densa which also decreases afferent resistance.

76

Week 227 - Acute Renal Injury: What does losartan do?

• Angiotensin receptor blocker.

77

Week 227 - Acute Renal Injury: What blood flow is required for effective dialysis?

200ml/min

78

Week 227 - Acute Renal Injury: What is a Scribner shunt?

An external AV shunt used to dialysis. Goes from the radial artery into a vein in the arm (Ulna side). Or ankle.

79

Week 227 - Acute Renal Injury: What is hyponatraemia?

• Low sodium (

80

Week 227 - Acute Renal Injury: What can cause the pituitary to release more ADH?

• Angiotensin II
• Sympathetic stimulation
• Hyperosmolarity
• Hypovolaemia
• Hypotension

81

Week 227 - Acute Renal Injury: How does Vasopressin/ADH increase arterial pressure?

• V1 receptors - Causes vasoconstriction
• V2 receptors - Renal fluid reabsorption

82

Week 227 - Acute Renal Injury: What are the causes of high plasma osmolality, than can in turn cause hyponatraemia?

• Hyperglycaemia, DKA
• Mannitol
• Hyperlipidaemia
• Glycine solutions

83

Week 227 - Acute Renal Injury: How is serum osmolality calculated?

(2x serum Na) + serum glucose + plasma urea

84

Week 227 - Acute Renal Injury: What are the causes of hyponatraemia with a normal/high serum osmolality?

• Renal failure - Uraemic solutes compensate for low osmolality.
• Marked hypoglycaemia, DKA
• Mannitol therapy - Osmotic diuresis.

85

Week 227 - Acute Renal Injury: What is pseudohyponatraemia?

Hyponatraemia caused by severe hyperlipidaemia or hyperproteinaemia.

86

Week 227 - Acute Renal Injury: Hyponatraemia can result from which three main mechanisms?

• High ADH
• Low ADH
• high plasma osmolality.

87

Week 227 - Acute Renal Injury: How can excessive exercise cause hyponatraemia?

• Increased water intake
• Exercise stimulates ADH secretion

88

Week 227 - Acute Renal Injury: How does MDMA cause life threatening hyponatraemia?

• Increased CNS level of serotonin, norepinephrine and dopamine.
• Increased plasma level of ADH, prolactin, cortisol, ACTH.
• Have a direct effect on water retention and thirst centre.

89

Week 227 - Acute Renal Injury: How does hyponatraemia occur when there is appropriate suppression of ADH?

• Renal failure - Impairment in water excretion.
• Primary polydipsia (thirst) - May be due to antipsychotic drugs, hypothalamic lesions, beer drinkers.

90

Week 227 - Acute Renal Injury: How does hyponatraemia clinically manifest?

• The severity of the symptoms reflect the severity of cerebral oedema.
- Nausea, confusion.
- Headache, lethargy.
- Convulsions, coma.

91

Week 227 - Acute Renal Injury: What investigations should be performed for suspected hyponatraemia?

• Serum osmolality
• Urine osmolality
• Urinary Na concentration

92

Week 227 - Acute Renal Injury: What investigation results would suggest SIADH?

• Low serum osmolality
• Low serum Na
• Low blood urea
• High urine osmolality
• High urinary Na
• Normal acid/base balance
• Normal adrenal and thyroid function.

93

Week 227 - Acute Renal Injury: What is the management of hyponatraemia?

• Treat underlying cause!
• Fluid restriction
• Salt replacement
• Loop diuretics
• ADH receptor antagonist

94

Week 227 - Acute Renal Injury: What should the rate of correction be in both acute and chronic hyponatraemia?

• Acute - safe to correct rapidly.

• Chronic - Risk of osmotic demyelination
- Increase by 10 in 1st 24hrs
- Increase by 18 in next 24 hrs.

95

Week 227 - Acute Renal Injury: Which drugs can cause hypokalaemia?

• Thiazide diuretics
• Loop diuretics

96

Week 227 - Acute Renal Injury: Which drugs can cause hyperkalaemia?

• ACE inhibitors
• Angiotensin receptor blockers
• Spironolactone

97

Week 227 - Acute Renal Injury: The long term use of which drugs may cause irreversible renal damage?

• Aminoglycosides (gentamicin)
• NSAIDs

98

Week 227 - Acute Renal Injury: Which drugs can cause rhabdomyolysis / High CK?

• Statins
• Calcineuin inhibitors : Cyclosporin / tacrolimus

99

Week 227 - Acute Renal Injury: What is the most appropriate investigation? A patient presented with ARF, chest symptoms, urine dipstock showed blood +++ and protein +++.

Renal Biopsy

100

Week 227 - Acute Renal Injury: What is the most appropriate investigation? Patient presented with ARF, fever, night sweats, dysuria and loin pain.

Urine microscopy looking for cell casts, urine culture.

101

Week 227 - Acute Renal Injury: What is the most appropriate investigation? An elderly patient developing ARF 4 days after knee replacement.

Urinary Na

102

Week 227 - Acute Renal Injury: What is the most appropriate investigation? Patient with symptoms of poor stream, dribbling hesitancy and nocturia developing a gradual rise of serum urea and creatinine.

Physical examination and bladder scan.

103

Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. ARF after a marathon run.

Hypocalcaemia

104

Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. Recovery phase of ARF due to rhabdomyolysis.

Hypercalcaemia

105

Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. ARF after introduction of ACE inhibitor in a patient with chronic heart failure.

Hyperkalaemia

106

Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. Chronic use of thiazide diuretics.

Hypokalaemia

107

Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. RBC cast.

Glomerulonephritis

108

Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. WBC cast.

Pyelonephritis

109

Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. Fatty casts.

Nephrotic syndrome

110

Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. Pigmented casts.

Rhabdomyolysis