Pathophysiology of Acute Kidney Injury Flashcards
What is used to measure renal function
Urine volume
Serum creatinine - (U+E blood test)
Glomerular filtration rate - derived from serum creatine measurements
How much GFR is lost before serum creatinine loses its normal range
50%
What is the eGFR
Based on a formula derived from patients age, gender, ethnicity and serum creatinine
define acute kidney injury
A decrease in GFR which occurs within the hours to weeks and is potentially reversible
What does normal kidney function depend on
perfusion with adequate pressure and O2
intact nephrons
Free urinary drainage
Main causes of pre-renal AKI
Disordered perfusion
different types of shock can cause it too
Main cause of renal AKI
Damage to nephrons
What is the kidneys response to a decrease in perfusion
activation of RAAS
Increase in ADH secretion
What is Renal AKI
Loss of normal tubular function due to acute tubular necrosis
Signs of renal AKI in the urine
Na+
Causes of renal AKI
Renal ischaemia followed by reperfusion
Exposure to nephrotoxins
Features of renal AKI
Decrease
- urine osmolality
- urine specific gravity
- tubular K+ secretion
- tubular H+ secretion
Increase in urine Na+
increase in fractional excretion
What happens in post-renal acute injury
Urinary drainage is obstructed
Causes of post renal acute injury
problems in the lumen, in the wall or outside the wall
How to treat a post renal acute UTI
Exclude/relieve obstruction
Treat underlying cause of renal tract obstruction
prevent. treat UTI
