Week 227 - Acute Renal Injury Flashcards
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.
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.
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.
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,
Week 227 - Acute Renal Injury: What is the ‘triad’ of Rhabdomyolysis?
1) Myalgia
2) Generalized weakness
3) Tea-coloured urine.
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).
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
Week 227 - Acute Renal Injury: Which drugs can cause rhabdomyolysis?
• Alcohol, opiates, statins, colchicine, cyclosporin.
Week 227 - Acute Renal Injury: How is rhabdomyolysis induced AKI diagnosed?
- History
- Red to brown urine
- Elevated serum enzyme level - CK, LDH
- Electrolyte abnormalities.
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)
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.
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.
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.
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.
Week 227 - Acute Renal Injury: The presence of a white blood cell cast indicates which disease state?
• Acute pyelonephritis or interstitial nephritis.
Week 227 - Acute Renal Injury: The presence of a fatty cast indicates the presence of which disease state?
• Lipiduria
- E.g. nephrotic syndrome.
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.
Week 227 - Acute Renal Injury: The presence of a pigmented cast indicates the presence of which disease states?
- Haemoglobinuria
* Myoglobinuria
Week 227 - Acute Renal Injury: What is the shape of calcium oxalate crystals?
Square, enveloped shapes.
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
Week 227 - Acute Renal Injury: What shape are uric acid crystals? What does their presence indicate?
- Diamond shaped.
* Hyperuricaemia.
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.
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.
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.
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.
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.
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.
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
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
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
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
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
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
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
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.
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.
Week 227 - Acute Renal Injury: How is third space sequestration treated?
• Abdominal decompression.
- Paracentesis
- Surgical decompression
Week 227 - Acute Renal Injury: What is the normal GFR?
120 ml/min, >7L/hr
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.
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.
Week 227 - Acute Renal Injury: What type of acute kidney injury is acute tubular necrosis?
Intrinsic
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.
Week 227 - Acute Renal Injury: What is the most common form of intrinsic acute renal failure?
• Acute Tubular Necrosis (ATN)
Week 227 - Acute Renal Injury: What is the mortality rate of uncomplicated ATN?
7%-23%
Week 227 - Acute Renal Injury: 50% of radiocontrast nephropathies develop after which procedures?
• Cardiac diagnostic and interventional procedures.
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
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)
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.
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.
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.
Week 227 - Acute Renal Injury: What are the three life-threatening complications of acute kidney injury?
- Metabolic Acidosis
- Hyperkalaemia
- Acute pulmonary oedema
Week 227 - Acute Renal Injury: How is the serum anion gap calculated?
AG = Cations - Anions AG= Na + K - Cl - HCO3
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.
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.
Week 227 - Acute Renal Injury: What is the clinical effect of a metabolic acidosis?
- Muscle weakness
- Altered mental state
- Kussmaul breathing
- Hyperkalaemia
- Hypotension
Week 227 - Acute Renal Injury: What is Kussmaul breathing?
- Deep and labored breathing.
* Associated with severe metabolic acidosis.
Week 227 - Acute Renal Injury: What is the treatment of metabolic acidosis?
- Treat the cause!
- Volume expansion
- IV sodium bicarbonate (Only in severe acidosis
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.
Week 227 - Acute Renal Injury: What are the ECG changes associated with hyperkalaemia?
- Loss of p waves.
- AV block
- Bradycardia
- V tachycardia
- Asystole
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.
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
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.
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)
Week 227 - Acute Renal Injury: ACE is responsible for what step in the renin-angiotensin system?
Conversion of angiotensin I into angiotensin II.
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.
Week 227 - Acute Renal Injury: Where are the juxtaglomerular cells?
Afferent arterioles.
Week 227 - Acute Renal Injury: Where is the macula densa?
Distal tubular cells.
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.
Week 227 - Acute Renal Injury: How does the kidney respond to high BP?
Afferent arteriolar constriction in order to protect the glomeruli.
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.
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.
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.
Week 227 - Acute Renal Injury: What can cause the dilation of the afferent arterioles?
- Prostaglandins
- Ca channel blockers
- Decreased tubular flow rate.
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
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.
Week 227 - Acute Renal Injury: What does losartan do?
• Angiotensin receptor blocker.
Week 227 - Acute Renal Injury: What blood flow is required for effective dialysis?
200ml/min
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.
Week 227 - Acute Renal Injury: What is hyponatraemia?
• Low sodium (
Week 227 - Acute Renal Injury: What can cause the pituitary to release more ADH?
- Angiotensin II
- Sympathetic stimulation
- Hyperosmolarity
- Hypovolaemia
- Hypotension
Week 227 - Acute Renal Injury: How does Vasopressin/ADH increase arterial pressure?
- V1 receptors - Causes vasoconstriction
* V2 receptors - Renal fluid reabsorption
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
Week 227 - Acute Renal Injury: How is serum osmolality calculated?
(2x serum Na) + serum glucose + plasma urea
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.
Week 227 - Acute Renal Injury: What is pseudohyponatraemia?
Hyponatraemia caused by severe hyperlipidaemia or hyperproteinaemia.
Week 227 - Acute Renal Injury: Hyponatraemia can result from which three main mechanisms?
- High ADH
- Low ADH
- high plasma osmolality.
Week 227 - Acute Renal Injury: How can excessive exercise cause hyponatraemia?
- Increased water intake
* Exercise stimulates ADH secretion
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.
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.
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.
Week 227 - Acute Renal Injury: What investigations should be performed for suspected hyponatraemia?
- Serum osmolality
- Urine osmolality
- Urinary Na concentration
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.
Week 227 - Acute Renal Injury: What is the management of hyponatraemia?
- Treat underlying cause!
- Fluid restriction
- Salt replacement
- Loop diuretics
- ADH receptor antagonist
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.
Week 227 - Acute Renal Injury: Which drugs can cause hypokalaemia?
- Thiazide diuretics
* Loop diuretics
Week 227 - Acute Renal Injury: Which drugs can cause hyperkalaemia?
- ACE inhibitors
- Angiotensin receptor blockers
- Spironolactone
Week 227 - Acute Renal Injury: The long term use of which drugs may cause irreversible renal damage?
- Aminoglycosides (gentamicin)
* NSAIDs
Week 227 - Acute Renal Injury: Which drugs can cause rhabdomyolysis / High CK?
- Statins
* Calcineuin inhibitors : Cyclosporin / tacrolimus
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
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.
Week 227 - Acute Renal Injury: What is the most appropriate investigation? An elderly patient developing ARF 4 days after knee replacement.
Urinary Na
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.
Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. ARF after a marathon run.
Hypocalcaemia
Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. Recovery phase of ARF due to rhabdomyolysis.
Hypercalcaemia
Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. ARF after introduction of ACE inhibitor in a patient with chronic heart failure.
Hyperkalaemia
Week 227 - Acute Renal Injury: Choose the electrolyte abnormality. Chronic use of thiazide diuretics.
Hypokalaemia
Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. RBC cast.
Glomerulonephritis
Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. WBC cast.
Pyelonephritis
Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. Fatty casts.
Nephrotic syndrome
Week 227 - Acute Renal Injury: Match the following urinary casts to the pathological conditions. Pigmented casts.
Rhabdomyolysis