AKI Flashcards
Location of the kidneys?
Retroperitoneal against the posterior abdominal wall
Proportion of cardiac output received by the kidneys?
20-25%
Sections of the nephron within the cortex?
- Glomerulus
- Bowmann’s capsule
- Convoluted tubules
Sections of the nephron within the medulla?
- Loop of Henle
- Collecting duct
Causes of AKI can be divided into ?
- Pre-renal
- Renal
- Post-renal
What are the causes of pre-renal AKI? This is 20% of AKI!
- Renal hypoperfusion
- Hypovolaemia or hypotension
What is the consequence of AKI?
- Retention and accumulation of waste products
- Dysregulation of ECF volume
- Electrolyte disturbances
What is the functions of the different parts of the nephron?
- Bowman’s capsule & glomerulus - Ultrafiltration
- Proximal tubule - Selective re-absorption
- Loop of Henle - Osmoregulation
- DCT - selective re-absorption
- Collecting duct - Osmoregulation
What occurs in proximal tubule selective re-absorption ?
- Glucose
- Amino acids
- Urea
- Sodium
- Potassium
- Phosphate
- Calcium
- Magnesium
- Water
- Bicarbonate
What are osmoregulated in the loop of henle? Ascending loop!
- Sodium
- Potassium
- Magnesium
- Calcium
What is selectively re-absorbed in the DCT?
- Urea
- Sodium
- Calcium
- Magnesium
- Water
- Bicarbonate
What are osmoregulated in the loop of collecting duct ?
- Sodium
- Water
What are the functions of the kidney ?
- Maintenance of fluid balance
- Electrolyte regulation
- Acid-base balance
- Excretion of waste products - Ur, Cr, uric acid & NH
- Excretion & metabolism of drugs
- BP control via RAA system
- Vitamin D activation
- Production of erythropoietin
How is renal function assessed?
By assessment of GFR
What is GFR
This is the rate at which protein free plasma is filtered from glomeruli into the bowman’s capsule per unit time
What methods can be used in assessing GFR?
- Directly - Insulin
- Indirectly - Creatinin
What are the causes of renal AKI? This is 70% of AKI!
This is due to structural damage to the kidney
- Acute tubular necrosis
- Glomerulonephritis
Definition of stage 1 AKI?
- Increase in creatinine 1.5-1.9 times baseline
- Increase by > 26.5 micro mole/L
- Reduction in UO < 0.5 ml/kg/hr for 6-12 hrs
Definition of stage 2 AKI?
- Increase of creatinine 2 - 2.9 of baseline
- Reduction in UO of < 0.5 ml/kg/hr for > 12hrs
Definition of stage 3 AKI?
- Increase in creatinine > 3 times baseline
- Initiation of RRT
- In patient < 18 with eGFR < 35 ml/min/1.73m2
- Reduction in UO < 0.3ml/kg/hr for 24 hours
- Anuria for 12 hrs
Aetiologies of pre-renal AKI?
- Hypovolaemia
- Hypotension
- Afferent arteriole constriction (ACEI, Renal artery stenosis, hepato-renal syndrome)
Aetiologies of renal AKI?
- Acute tubular necrosis (Ischaemia, drug, Rhabdomyolysis )
- Glomerulonephritis (Acute interstitial nephritis, drugs)
- Others: SLE , TB Sarcoidosis
Aetiologies of post-renal AKI?
- Renal calculi
- Ureteric (Stones, stricture, tumour or clots)
- Extrinsic pressure - Cancer
What are the complications of AKI?
- Metabolic acidosis
- Hyperkalaemia
- Fluid overload
- Hypocalcaemia
- Low phosphate
- Anaemia
- Uraemia
