AKI Flashcards
What is Acute Kidney Injury (AKI)?
AKI refers to a rapid drop in kidney function, diagnosed by measuring serum creatinine. It is most common in acutely unwell patients, such as those with infections or following surgery.
What are the NICE guidelines (2019) criteria for diagnosing AKI?
Criteria include:
* 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
What are the risk factors for developing Acute Kidney Injury (AKI)?
Risk factors include:
* Older age (e.g., above 65 years)
* Sepsis
* Chronic kidney disease
* Heart failure
* Diabetes
* Liver disease
* Cognitive impairment
* Medications (e.g., NSAIDs, gentamicin, diuretics, ACE inhibitors)
* Radiocontrast agents (e.g., used during CT scans)
What is the TOM TIP for remembering the causes of renal impairment?
The causes are pre-renal, renal, or post-renal.
What are pre-renal causes of Acute Kidney Injury?
Pre-renal causes involve insufficient blood supply (hypoperfusion) to the kidneys, reducing filtration. Common causes include:
* Dehydration
* Shock (e.g., sepsis, acute blood loss)
* Heart failure
What are renal causes of Acute Kidney Injury?
Renal causes involve intrinsic disease in the kidney, such as:
* Acute tubular necrosis
* Glomerulonephritis
* Acute interstitial nephritis
* Haemolytic uraemic syndrome
* Rhabdomyolysis
What are post-renal causes of Acute Kidney Injury?
Post-renal causes involve obstruction of urine flow, leading to back-pressure into the kidney. Causes include:
* Kidney stones
* Tumours (e.g., retroperitoneal, bladder, prostate)
* Strictures of the ureters or urethra
* Benign prostatic hyperplasia
* Neurogenic bladder
What is Acute Tubular Necrosis (ATN) and how is it diagnosed?
ATN refers to damage and death of the epithelial cells of the renal tubules. It is the most common intrinsic cause of AKI. Diagnosis can be confirmed by the presence of muddy brown casts and renal tubular epithelial cells on urinalysis.
What are the causes of Acute Tubular Necrosis (ATN)?
ATN is caused by:
* Ischaemia due to hypoperfusion (e.g., dehydration, shock, heart failure)
* Nephrotoxins (e.g., gentamicin, radiocontrast agents, cisplatin)
How is Acute Tubular Necrosis (ATN) treated?
ATN is reversible with epithelial cells regenerating, typically recovering in 1-3 weeks.
What is Acute Interstitial Nephritis (AIN)?
AIN is inflammation of the interstitium (space between the tubules and vessels) of the kidney, caused by an immune reaction due to:
* Drugs (e.g., NSAIDs, antibiotics)
* Infections (e.g., E. coli, HIV)
* Autoimmune conditions (e.g., sarcoidosis, SLE)
What are common features of Acute Interstitial Nephritis (AIN)?
Features include:
* Rash
* Fever
* Flank pain
* Eosinophilia
How is Acute Interstitial Nephritis (AIN) managed?
Treatment involves addressing the underlying cause, with steroids often used to reduce inflammation and improve recovery.
What investigations are used in diagnosing Acute Kidney Injury (AKI)?
Investigations include:
* Urinalysis: To check for protein, blood, leucocytes, nitrites, and glucose
* Ultrasound: To check for obstruction in post-renal AKI
What are strategies for preventing Acute Kidney Injury (AKI)?
Strategies include:
* Avoid nephrotoxic medications where appropriate
* Ensure adequate fluid intake (including IV fluids if necessary)
* Administer additional fluids before and after radiocontrast agents
What are the treatments for Acute Kidney Injury (AKI)?
Treatments include:
* Reversal of underlying cause
* Supportive management (e.g., IV fluids for dehydration)
* Withholding or adjusting nephrotoxic medications
* Relieving obstruction in post-renal AKI
* Dialysis for severe cases
When is input from a renal specialist required in Acute Kidney Injury (AKI)?
Input is required in cases of severe AKI, uncertainty about the cause, or complications.
Why should ACE inhibitors be withheld in Acute Kidney Injury (AKI)?
ACE inhibitors should be stopped in AKI because they reduce filtration pressure, which worsens the condition. However, they have a protective effect on the kidneys long-term in certain patients.
What are the complications of Acute Kidney Injury (AKI)?
Complications include:
* Fluid overload, heart failure, pulmonary oedema
* Hyperkalaemia
* Metabolic acidosis
* Uraemia (high urea), leading to encephalopathy and pericarditis
