Flashcards in Acute And Chronic Kidney Disease Deck (88)
What is AKI?
Abrupt decline in actual GFR (days to weeks)
Upset of ECF volume, electrolytes and acid-base balance
Accumulation of nitrogenous waste products
Why is AKI difficult to diagnose?
Doesn't present with a specific identifiable symptom
Measurements are not massively accurate either
What happens to serum creatinine as kidneys decline?
Kidney decline leads to increased serum creatinine
How do we define AKI through measurements?
Increased serum creatine > 26.5 micromoles/L within 48 hrs
Increased serum creatinine > 1.5 x their baseline in 7 days
Urine volume <0.5 ml/kg/h for 6 hours
Describe the staging of AKI
1 - 3 in increasing severity
1 = 1.5 - 2 times their baseline
2 = 2 - 3 times their baseline
3 = > 3 times their baseline
What are the types of AKI?
What are the causes of pre-renal AKI?
Blood supply compromised
Give some renal causes of AKI
Renal artery/vein occlusion
What does ATN stand for?
Acute tubular necrosis
What type of AKI are the vast majority?
90% of intrinsic renal causes of AKI are due to ...
Give some general causes of AKI
Describe how pre-renal problems cause AKI
Actual GFR reduced due to decreased renal blood flow
No cell drainage
Kidney works hard to restore blood flow
Increased reabsorption of salt and water (lots of aldosterone and ADH)
Responds to fluid resuscitation
Describe autoregulation of the kidneys
Keeps the kidneys between a minimum and maximum BP over which they can maintain a normal perfusion pressure
When hypertensive, these values shift to higher BPs (reset)
What is the SM response to decreased renal perfusion?
Vasodilation of afferent
Vasoconstriction of efferent
Why do NSAIDs make AKI worse?
Inhibition of production of prostaglandins
Cannot vasodilate in the arterioles of kidneys when required
Cannot regulate perfusion pressure
Why can ACEi make AKI worse?
Cannot vasoconstrict when need to
Give some causes of reduced ECF volume
Give some causes of impaired renal autoregulation
What are the causes of ATN?
Why is ATN a misnomer?
As there is generally no tubular necrosis
But cells are damaged
Damaged cells cannot reabsorbed salt and water efficiently
Or expel excess water
Aggressive fluid resuscitation risks fluid overload
Lost the ability to concentrate urine therefore urine comes out at the same rate no matter the volume of ECF
If dialysis is required, does the mortality of AKI increased or decreased?
Which parts of the nephron are most susceptible to hypoxia?
S3 of PCT
Thick ascending limb LOH
Describe damage in the kidneys due to nephrotoxins
Damage the epithelial cells lining the tubules and cause cell death and shedding into the lumen
Can be endogenous or exogenous
ATN more likely if reduced perfusion and a nephrotoxin
Give examples of endogenous nephrotoxins
In which treatment does urate build up?
Give some examples of exogenous nephrotoxins
Drugs (ACEi, aminoglycosides, NSAIDs)
Poisons (weedkillers, antifreeze)
How does rhabdomylosis cause ATN?
Muscular necrosis releases myoglobin 'crush injury'
In wars and natural disasters
Can occur in drug users and elderly when cannot move
Myoglobin is toxic to tubule cells and can also cause obstruction