Renal - CKD and AKI Flashcards
define AKI
sudden decerase in kidney function
measured by an increase in serum creatinine or decreased urine output
what is stage 1 AKI?
serum creatinine 1.5-1.9 x baseline
or urine output < 0.5 ml/kg/h for 6-12 hours
what is stage 2 AKI?
serum creatinine 2.0-2.9 x the baseline or urine output <0.5 ml/kg/hour for >12 hours
what is stage 3 AKI?
serum creatinine 3 x the baseline
or urine output <0.3 ml/kg/hour for >24 hours or anuria for >12
or initiation of renal replacement therapy
what are the different categories of causes of AKI?
pre-renal AKI
intra-renal AKI
post-renal AKI
what are the causes of pre-renal AKI?
- Volume deflation - haemorrhage, severe vomiting, burns
- Effective volume depletion - sepsis, heart failure, cariogenic shock
- Renal hypoperfusion - renal artery stenosis, abdominal aortic aneurysm
- NSAIDs, ACEi, ARBs
what are the causes of intra-renal AKI?
- ischaemic injury
- nephrotoxic injury
- immune-mediated injury
what are the causes of post-renal AKI?
- obstruction to urinary collecting system
what is the presentation of AKI?
- reduced urine output
- signs of the cause of AKI (e.g. tachycardia, hypotension, vomiting)
signs of volume overload due to impaired salt and volume regulation by the kidneys (orthopnoea, peripheral oedema) - electrolyte imbalances
- acid-base disturbance
what investigations would you carry put when suspecting AKI?
- urine dipstick (can post towards cause e.g. proteinuria + haematuria suggests glomerular injury; haematuria suggests obstruction or tumours and leucocytes suggest infection or nephritis)
- catheter shows decreased urine output
- serum creatinine and urea (increased)
- urea and electrolytes (high serum potassium)
- ABG (metabolic acidosis)
- Urine culture
- FBC (anaemia can suggest CKD or blood loss and leucocytosis can suggest infection)
- Ultrasound to rule out obstruction and show underlying CKD
- consider an ECG due to possible changes due to hyperkalaemia
how would you manage AKI?
- If hypovolaemic, fluid bolus of 250-500 mL 0.9% NaCl + a vasopressor (dopamine or adrenaline)
- if euvolaemic give maintenance fluids and if hypervolaemic consider diuretics
- medication review, stop nephrotoxic drugs and antihypertensives if there is hypotension
- monitor urine output, urea and electrolytes, creatinine and fluid chart
- treat underlying cause
- bladder catheterisation if obstructive cause
- consider renal replacement therapy if indicated (usually haemodialysis)
define chronic kidney disease
GFR < 60 mL/min for at least 3 months
or persistent proteinuria or haematuria
how is CKD staged?
according to GFR
what is stage 1 CKD?
kidney damage with normal or increased GFR (GFR >90 mL/min)
what is stage 2 CKD?
Kidney damage with a mild decrease in GFR (60-89)
what is stage 3 CKD?
GFR 30-59
what is stage 4 CKD?
GFR 15-29
what is stage 5 CKD?
kidney failure
GFR<15 or dialysis
what are the causes of CKD?
- diabetes and hypertension are the most common causes
- chronic pyelonephritis
- polycystic kidney disease
what is the presentation of CKD?
- fatigue
- oedema
- nausea, vomiting
- pruritus
- anorexia
- bone disease
why can bone disease occur in CKD?
phosphate excretion by kidneys is impaired causing increased phosphate levels.
there is decreased active vitamin D (calcitriol) due to kidney disease and therefore decreased calcium.
decreased calcium and calcitriol levels cause increased PTH levels which causes bone resorption- cyst formation and bone marrow fibrosis.
why can CKD cause cardiovascular disease?
high urea levels can cause uraemia cardiomyopathy.
fluid retention causes LV overload and hypertrophy
what investigations are carried out when suspecting CKD?
- urine dipstick (haematuria, proteinuria)
- blood glucose (diabetes can cause CKD)
- FBC and haematinics (normocytic anaemia of chronic disease)
- urea and electrolytes (sodium and potassium abnormalities, increased urea)
- creatinine and eGFR to stage the CKD
- bone profile to check for metabolic bone disease (serum Ca, phosphate, Alk Phos, Mg, Vit D and PTH)
- complement components and autoantibody screen (e.g. for SLE)
- Ultrasound of renal tract
- chest Xray (pulmonary oedema)
- abdominalCT to look for calculi
what is the management of CKD?
- stages 1-2 with no uraemia: ACEi or ARB (lisinopril or losartan) for BP control. statin (simvastatin) for cardiovascular protection
- stages 3-4 with no uraemia: ACEi or ARB + statin +/- Ezetimibe
- stage 5 or uraemia: dialysis or kidney transplant
- any above with anaemia: erythropoietin stimulating agent (epoetin alfa) and iron (ferrous sulphate)
- any above with 2ry hyperparathyroidism (due to low calcitriol and calcium levels): dietary phosphate restriction, phosphate binders, ergocacalciferol (active vitamin D)
- any above with metabolic acidosis: oral sodium bicarbonate
define end-stage renal disease
irreversible chronic kidney damage that requires renal replacement therapy for survival
what is the presentation of end-stage renal disease?
same as CKD:
- lethargy
- weight loss
- pruritus
- oedema
- nausea
what is the management of end-stage renal disease?
- conservative treatment
- haemodialysis/peritoneal dialysis/renal transplant
- vaccination against hepatitis B
what are the indications for renal replacement therapy in CKD or end-stage renal disease?
- symptoms of uraemia
- fluid overload
- resistant hyperkalaemia
- resistant metabolic acidosis
- eGFR < 10mL/min/1.73m^2 (normal is 90-120)
what are the signs of uraemia?
- weight loss
- anorexia
- nausea/vomiting
- acidosis
- hyperkalaemia
- fluid overload
(same as CKD signs/symptoms)
