Chempath 19: Assessment Of Renal Function 2 Flashcards
Define acute kidney injury ?
Rapid abrupt reduction in kidney function leading to inability to maintain electrolytes, acid-base and fluid haemostasis
A patient on the ward has an increase of creatinine clearance of 30 µmol/L. Is this patient having an AKI ?
Yes
AKI stage 1: increase of serum creatinine by >= 26µmol/L or >1.5 x reference serum creatinine
AKI stage 2: >2x reference serum creatinine
AKI stage 3: >3x reference serum creatinine or increase >= 354µmol/L
Outline 2 physiological mechanisms that work to maintain GFR and renal blood flow at a constant rate ?
Myogenic stretch- If the afferent arteriole is stretched due to high pressure, it will constrict in order to keep blood pressure entering Glomerulus constant (and GFR)
Tubuloglomerular feedback- High chloride ions are detected in the afferent arteriole, this triggers it to constrict to reduce GFR and chloride ions in the distal tubule
List 4 pre-renal causers of AKI (excluding drugs) ?
Haemorrhage
Hypotension (shock, sepsis, anaphylaxis)
Oedema (HF, Cirrhosis, nephrotic syndrome)
renal artery stenosis
List 4 drugs that can cause pre-renal AKI ?
ACE inhibitors- reduce efferent arteriole vasoconstriction
NSAIDs - decreases afferent arteriole dilation
Calcineurin inhibitors- decrease afferent arteriole dilation
Diuretics- reduce preload, affect tubular function
What is the difference between AKI and ATN (acute tubular necrosis) ?
AKI has no structural damage and responds immediately to restoration of the circulation volume.
ATN is caused by Ischaemic damage and will not respond to correction of the circulating volume.
In ATN what feature may be seen in the urine on microscopy?
Epithelial cell casts
List 4 post renal causes of AKI?
Renal calculi (stones) BPH Blocked urinary catheter Urethral strictures Cervical cancer
Anything that blocks the outflow of urine from the kidneys. This causes increased pressure in the tubules, which reduces the pressure gradient across the Bowman’s capsule and hence causes GFR to decline.
List 4 renal causes AKI?
Glomerulonephritis
ATN
Small vessel vasculitis- (HSP, Churg-Strauss syndrome, microscopic polyangitis, granulomatosis with polyangitis)
Interstitial nephritis
What measure is used to stage Chronic kidney disease (CKD)
GFR
Which stage of CKD is considered end-stage kidney failure?
What GFR indicates this ?
Stage 5
GFR <15 or dialysis dependent
Which one of these is not considered a common risk factor for CKD ?
A) Diabetes mellitus B) Obesity C) hypertension D) drinking 5 glasses of water per day E) Renal stones F) Polycystic kidney disease
D) drinking 5 glasses of water per day
This is a healthy amount of water
All the others are risk factors for CKD
Which 3 endocrine functions of the kidneys may be disturbed during CKD ?
EPO- required for haemopoiesis
RAS- renin release for ADH secretion
Vitamin D- The kidney activates vitamin D to calcitriol
What kind of acid base dysfunction would you expect in CKD ?
Metabolic Acidosis
You can no longer make HCO3- ions to mop up excess H+
List some signs/symptoms of Uraemia ?
Nausea and vomiting Progressive weakness Shallow respiration coma Tremor