Acute Kidney Injury (AKI) Flashcards
(22 cards)
What does acute kidney injury (AKI) refer to?
A rapid drop in kidney function, diagnosed by measuring serum creatinine
What are the NICE guidelines criteria for diagnosing acute kidney injury?
- Rise in creatinine of more than 25 micromol/L in 48 hours
- Rise in creatinine of more than 50% in 7 days
- Urine output of less than 0.5 ml/kg/hour over at least 6 hours
List nine risk factors for developing acute kidney injury
- Older age (above 65 years)
- Sepsis
- Chronic kidney disease
- Heart failure
- Diabetes
- Liver disease
- Cognitive impairment, leading to reduced fluid intake
- Certain medications e.g., NSAIDs, gentamicin, diuretics and ACE inhibitors
- Radiocontrast agents e.g., used during CT scans
What are common causes of acute kidney injury categorized as pre-renal?
- Dehydration
- Shock (e.g., sepsis or acute blood loss)
- Heart failure
What are renal causes of acute kidney injury?
- Acute tubular necrosis
- Glomerulonephritis ( = inflamed glomeruli in kidney)
- Acute interstitial nephritis ( = acute inflammation of the interstitium between the tubules and vessels)
- Haemolytic uraemic syndrome
(= damage to endothelial cells of small blood vessels stimulates clotting; microthombi form thereby partially blocking the vessels; blood cells experience mechanical damage as they pass through these partially blocked vessels; damaged blood cells accumulate and eventually exceed capacity of kidney to remove them; waste products of blood cell damage accumulate and this injures kidney)
- Rhabdomyolysis
What is an obstructive uropathy?
Obstruction to the outflow of urine away from the kidney, causing back-pressure into the kidney. This is a post-renal cause of acute kidney injury (AKI).
List the five post-renal causes of acute kidney injury
- Kidney stones
- Tumours (e.g., bladder or prostate)
- Strictures/abnormal narrowing of the ureters or urethra
- Benign prostatic hyperplasia (benign enlarged prostate)
- Neurogenic bladder ( = impaired function of bladder due to damage to nerves that control it)
What is acute tubular necrosis?
Damage and death of the epithelial cells of the renal tubules
What are common causes of acute tubular necrosis?
- Ischaemia due to hypoperfusion
- Nephrotoxins (e.g., gentamicin, radiocontrast agents)
What confirms acute tubular necrosis on urinalysis?
Muddy brown casts/urinary sediment and renal tubular epithelial cells (small, often rounded or oval, cells with a large, distinct, eccentric nucleus)
What characterizes acute interstitial nephritis?
Acute inflammation of the interstitium between the tubules and vessels
Acute interstitial nephritis is an immune reaction. List three causes of this immune reaction.
- Drugs (e.g., NSAIDs or antibiotics)
- Infections (e.g., E. coli or HIV)
- Autoimmune conditions (e.g., sarcoidosis or SLE)
What are some accompanying features of acute interstital nephritis?
- Rash
- Fever
- Flank pain
What does urinalysis assess for in acute kidney injury and what does each feature suggest?
- Protein
- Blood
Protein and blood suggest acute nephritis - Leucocytes
- Nitrites
Leucocytes and nitrites suggest infection - Glucose
Glucose suggests diabetes
What does ultrasound of the urinary tract assess for?
Obstruction when a post-renal cause is suspected
What are three preventive measures for acute kidney injury?
- Avoid nephrotoxic medications where appropriate
- Ensure adequate fluid intake
- Additional fluids before and after radiocontrast agents
( = substances, often iodine-based, used to improve the visibility of internal structures in X-ray-based imaging techniques like CT scans and radiography;
- radiocontrast agents directly damage kidney tubules, cause renal vasoconstriction and hence medullar hypoxia that causes renal damage; IV fluids dilutes the radiocontrast and improves renal blood flow.)
Treating acute kidney injury (AKI) involves reversing the underlying cause and improving their quality of life by treating as soon as possible i.e. supportive management. What may supportive management for AKI entail?
- IV fluids to treat dehydration
- Withhold medications that may worsen the condition e.g., NSAIDs and ACE inhibitors
- Withhold/adjust medications that may accumulate due to reduced renal function e.g., metformin and opiates
- Relieve the obstruction in a post-renal AKI e.g., insert a catheter in a patient with prostatic hyperplasia (enlarged prostate presses on urether, obstructing renal outflow and causing AKI)
- Dialysis may be required if severe complications occur and are resistant to treatment e.g. acidosis; electrolyte imbalances, especially hyperkalemia; oedema i.e. severe fluid overload; uremia/excess blood level of urea
What are potential complications of acute kidney injury and what further complications, if any, could they lead to?
- Fluid overload which can lead to * pulmonary oedema and * heart failure
- Hyperkalaemia
- Metabolic acidosis
- Uremia/excess blood levels of urea which can lead to * encephalopathy and * pericarditis
True or False: ACE inhibitors are considered nephrotoxic.
False
The epithelial cells of the renal tubules die in acute tubular necrosis, however they can regenerate. What is the recovery time for acute tubular necrosis?
Usually 1-3 weeks
Fill in the blank: Acute kidney injury is most common in _______ patients.
[acutely unwell]
What is the most common intrinsic cause of acute kidney injury (AKI)?
Acute tubular necrosis
