W14 - AKI & CKD Flashcards
AKI is a rapid reduction in kidney function, leading to inability to …. 3 things - list them.
Maintain electrolyte (1), acid-base (2), and fluid (3) homeostasis
NHS England defines stages of AKI based on what measurement?
Serum Creatinine (sCr)
Define the stages of AKI
AKI Stage 1: Increase in sCr by ≥26 µmol/L, or by 1.5 to 1.9x the reference sCr
AKI Stage 2: Increase in sCr by 2.0 to 2.9x the reference sCr
AKI Stage 3: Increase in sCr by ≥3x the reference sCr, or increase by ≥354 µmol/L
The type of AKI is divded into … (3)
- Pre-renal
- Intra-renal
- Post-renal
What is the hallmark of pre-renal AKI?
Persistent reduced renal perfusion despite normal adaptive mechanisms (i.e. activation of RAS, release of vasopressin, activation of sympathetic system = vasoconstriction, increased C.O., and renal sodium retention)
Causes (5) of pre-renal AKI
- True volume depletion
- Hypotension
- Oedematous states
- Selective renal ischaemia
- Drugs affecting glomerular blood flow ((NSAIDs, calcicneurin inhibitors, ACEi, or ARBs, diuretics)
Describe the 5 classes of drugs that predispose to pre-renal AKI and describe MOA of each
- NSAIDs - decrease afferent arteriolar dilatation
- Calcineurin inhibitors - as above
- ACEi - decrease efferent arteriolar constriction
- ARBs - as above
- Diuretics – affect tubular function, decrease preload
A 68 year old man with previously normal renal function is found to have a creatinine of 624μmol/l. Renal ultrasound shows the following appearance in both kidneys. What is the likely cause of his AKI?
A.Right-sided kidney stone
B.Left ureteric transitional cell carcinoma
C.Membranous glomerulonephropathy
D.Benign prostatic hypertrophy
E.Amyloid
Classic image of hydronephrosis = some obstruction to the kidneys = most likely here is
D.Benign prostatic hypertrophy
What is the hallmark of post-renal AKI?
Hallmark of post-renal AKI is a physical obstruction to urine flow
Give 3 main specific causes of post-renal AKI
- Ureteric obstruction (i.e. renal calculi)
- Urethral obstruction (i.e. prostatic obstruction)
- Blocked urinary catheter (i.e. clots)
What is the pathophysiology behind post-renal obstruction leading to AKI?
Obstruction results in increased tubular pressure
GFR is dependent on hydraulic pressure gradient
reduced gradient = immediate decline in GFR = creatinine will rise acutely (likely to 1000s)!
What 3 structural damages could occur due to prolonged post-renal obstruction?
- Glomerular ischaemia
- Tubular damage
- Long-term interstitial scarring
therefore imp to immediately relief obstruction!
Intra-renal AKI = What are 4 parts of the nephron that could be affected?
- Vascular disease (i.e. vasculitis)
- Glomerular disease (i.e. glomerulonephritis)
- Tubular disease (i.e. ATN)
- Interstitial disease (i.e. analgesic/NSAID nephropathy)
Patient has new onset AKI. What is the likely diagnosis?
Rhabdomyolysis
Patient who potentially has fallen, lots of myoglobin release, which has blocked their tubule and caused AKI
A 40 year old female presents with a rash and AKI is diagnosed. What is the most likely cause of her renal failure from the following list?
A.NSAIDs
B.Systemic vasculitis
C.Amyloidosis
D.Tumour lysis syndrome following chemotherapy for lymphoma
E.Myeloma
B. Systemic vasculitis