Renal/Genitourinary Flashcards
(203 cards)
Functions of the kidney
AWETBED
Acid-base homeostasis
Water balance
Electrolyte balance
Toxin/waste product removal
Blood pressure control
Ertyhropoietin
D (vitamin D activation)
Define Acute Kidney Injury
A sudden decline in kidney function leading to a rise in serum creatinine and fall in urine output.
What can renal dysfunction cause
Dysregulation of
- Fluid balance
- Acid-base homeostasis
- Electrolyte imbalance
Drugs to stop in acute kidney injury
DAAMN
D - Diuretics
A - ACEi/ARB
A - Aminoglycosides
M - Metformin
N - NSAIDs
ACEi/ARB protective in Chronic
6 pre renal causes of AKI
Hypoperfusion
- Hypovolaemia (bleeding, reduced cardiac output (CHF), cardiogenic shock)
- Liver failure (hypoalbuminaemia)
- Renal artery blockage/stenosis
- ACEi & NSAID
- Sepsis causing systemic vasodilation
- Dehydration
4 intrarenal causes of AKI
Intrinsic disease of kidney
- Acute tubular necrosis
- Acute interstitial nephritis (these 2 can be drug induced)
- Glomerulonephritis
- Small vessel vasculitis
4 post renal causes of AKI
Obstruction to urinary outflow, causing back pressure into kidney. (Obstructive uropathy)
- BPH
- Urolithiasis
- Cervical and prostate cancer
- Bladder neck stricture
Risk factors of AKI
- Age >65
- Heart failure
- Diabetes
- Poor fluid intake
- Hypovolaemia
- Nephrotoxic meds (NSAID, ACEi)
- Contrast medium usage in imaging
- Prostate cancer
- BPH
- Sepsis
- Liver disease
Electrolyte consequences of AKI
Hyperkalaemia and azotaemia (increased blood creatinine and urea)
Metabolic acidosis
Symptoms of pre renal AKI
Hypotension
Reduced capillary refill
Dry mucus membranes
Reduced skin turgor
Cool extremities
Intra renal AKI symptoms
Infection/ signs of underlying disease (vasculitis, glomerulonephritis etc)
Post renal AKI symptoms
Loin to groin pain
Haematuria
Palpable bladder/prostate
Prostatic urinary issues (dysuria, terminal dribbling, hesitancy)
Causes of Acute tubular necrosis
Ischaemia - Pre renal disease
Nephrotoxicity - (aminoglycosides, chemotherapy), contrast in CT, myoglobin, multiple myeloma
Pathophysiology of acute tubular necrosis
Nephrotoxins (aminoglycosides, NSAIDs, uric acid) can kill epithelial cells. When cells die, they block tubules increasing pressure. Less filtration occurs, causing azotaemia, hyperkalaemia and metabolic acidosis.
Pathophysiology of prerenal AKI
Less blood into kidney usually due to hypovolaemia causes activation of RAAS system
Na+ and urea reabsorbed, leading to oliguria
Causes less urine output which is more concentrated
Diagnostic criteria for AKI (stage 1)
- Rise in creatinine > 26μmol/L within 48 hours
- Rise in creatinine >1.5 x baseline (i.e. before the AKI) within 7 days.
- Urine output <0.5ml/kg/hour for >6 consecutive days.
Investigations in AKI
Check for hypo/hypervolaemia and urine output
FBC, U&E, ABG, Creatinine Kinase, Urine output should all be checked.
Urinalysis
Imaging
- Ultrasound - urinary tract to look for obstruction
- CXR - Signs of volume overload (cardiomegaly, pulmonary oedema)
- ECG - Hyperkalaemic changes
- CTKUB check obstruction
What urinalysis is conducted in AKI
Urine osmolality and electrolytes checked
Dipsticks - Leucocytes and nitrites = infection
Protein/ blood = acute nephritis
Glucose suggests diabetes
Treatment of AKI
Prerenal: IV fluids and treatment of sepsis
Intrarenal: Stop nephrotoxic drugs, treatment specific to condition
Post renal: Catheter in BPH
Treatment of AKI complications
Hyperkalaemia
- Calcium gluconate (protect myocardium)
- Insulin/dextrose (drive K+ into cells)
- Stop K+ sparing medication
Acidosis
- Sodium bicarbonate
Pulmonary oedema/hypervolaemia
- Diuretics
Complications of AKI
- Hyperkalaemia
- Fluid overload from treatment
- Metabolic acidosis
- Uraemia (encephalopathy/pericarditis)
- CKD
Classification systems in AKI
KDIGO (Kidney Disease: Improving Global Outcomes)
RIFLE (Risk Injury Failure Loss Endstage renal disease)
Staging of AKI
KDIGO criteria
Stage 1
- Creatinine >26 or 1.5-1.9x baseline in <48hr
- Urine output <0.5ml/kg/hr for 6-12 hours
Stage 2
- >2-2.9x baseline creatinine
- Urine output <0.5ml/kg/hr for >12 hours
Stage 3
>353 or 3x reference creatinine
<0.3ml/kg/hr for >24 hours or anuria for >12
Define CKD
Progressive deterioration in renal function over at least 3 months characterised by eGFR of <60ml/min/1.73m²