Acute renal failure (AKI and CKD) Flashcards
Define AKI
A rapid (within 7 days) and sustained (>24 hours) reduction in renal failure resulting in oliguria and a rise in serum urea and creatinine
NICE criteria for AKI
- Rise in creatinine of ≥ 25 micromol/L in 48 hours
- Rise in creatinine of ≥ 50% in 7 days
- Urine output of < 0.5ml/kg/hour for > 6 hours
List 4 risk factors for AKI
- CKD
- Heart failure
- Diabetes
- Liver disease
- Age > 65 years
- Nephrotoxic medications
- contrast medium during CT scans.
List the 3 types of AKI and which is the most common
- Pre-renal (55%)
- Intrinsic/ renal (35%)
- Post- renal (20%)
List 3 causes of pre-renal AKI
- Shock (hypovolaemic, cardiogenic, distributive)
- Renal artery stenosis
- Hypovolaemia (diarrhoea/vomiting or dehydration)
List 4 causes of intrinsic renal AKI
- Acute glomerulonephritis
- ATN
- Acute interstitial nephritis
- Rhabdomyolysis
List 4 causes of post-renal AKI
- Kidney stones
- pelvic or abdominal masses
- ureteral strictures or compression
- BPH or prostate cancer
How does AKI present?
May be asymptomatic or as renal failure progresses:
- reduced urine output
- pulmonary and peripheral oedema
- arrhythmias (changes in K+ and acid-base balance)
- features of uraemia (eg. pericarditis or encephalopathy)
Investigations for AKI?
- U&Es
- Urinalysis
- Renal ultrasound
Management of AKI?
- ABCDE
- Identify and treat underlying cause
- IV fluids in pre-renal AKI
- Stop nephrotoxic and renally excreted drugs
- Relieve obstruction in a post-renal AKI
List 4 examples of nephrotoxic medications
- NSAIDs
- ACEi
- ARBs
- Aminoglycosides eg. gentamicin
List 2 examples of renal excreted drugs
- Metformin
- Lithium
- Digoxin
List 3 treatments for hyperkalaemia?
- IV calcium gluconate
- Insulin/dextrose infusion and/or nebulised salbutamol
- Dialysis.
List 4 complications of AKI
- Hyperkalaemia
- Fluid overload, heart failure and pulmonary oedema
- Metabolic acidosis
- Uraemia can lead to encephalopathy or pericarditis
Indications for renal replacement (dialysis) in the acute setting?
- Acidosis
- Electrolytess - hyperkalaemia
- Intoxication (poisoning)
- Oedema - refractory pulmonary oedema
- Uraemia - encephalopathy or pericarditis
Why may serum creatinine may not be useful in determining eGFR?
What is used instead?
Due to differences in muscle
What is CKD?
Gradual, irreversible decline in kidney function for more than 3 months?
Requires either a decreased GFR (<60) or markers of kidney damage (albuminuria, electrolyte abnormalities etc..)
List 4 causes of CKD
- Diabetes
- Hypertension
- Age
- Glomerulonephritis
- Polycystic kidney disease
- Medications such as NSAIDS, proton pump inhibitors and lithium
List 4 risk factors for CKD
- Older age
- Hypertension
- Diabetes
- Smoking
- Medications that affect the kidneys
How does CKD present?
Usually asymptomatic (diagnosed on routine testing) but features may incl
- Pruritus (itching)
- Loss of appetite
- Nausea
- Oedema
- Muscle cramps
- Peripheral neuropathy
- Pallor
- Hypertension
Investigations for CKD?
- eGFR: using U&E blood test
- Proteinuria and Haematuria
- Albumin:creatinine ratio (ACR) -≥ 3
- Renal ultrasound
How is CKD staged?
G score based on the eGFR:
- G1 = >90
- G2 = 60-89
- G3a = 45-59
- G3b = 30-44
- G4 = 15-29
- G5 = <15 (“end-stage renal failure”)
A score based on the ACR
- A1 = < 3
- A2 = 3 – 30
- A3 = > 30
When does NICE recommend CKD should be referred to a specialist?
- eGFR < 30
- ACR ≥ 70 mg/mmol
- Accelerated progression
- Uncontrolled hypertension despite ≥ 4 antihypertensives
Aims of CKD management?
Slow the progression
Reduce risk of CVD
Reduce the risk of complications
Treating complications
What medication is offered for primary prevention of CVD?
Atorvastatin 20mg
List 4 complications of CKD
- Anaemia (↓EPO)
- Renal bone disease (CKD-MBD)
- CVD
- Peripheral neuropathy
- Hypertension
- Dialysis related problems
List 4 features of Renal bone disease
- Osteoporosis
- Osteomalcia
- Osteosclerosis
- 2o Hyperparathyroidism
Pathophysiology of renal bone disease?
- Descreased Vit D (no 1-alpha hydroxylation in kidneys)
- ↑ phosphate and ↓ calcium
- 2o hyperparathyroidism
What x-ray changes are associated with renal bone disease
Spine xray shows sclerosis of both ends of the vertebra and osteomalacia in the centre
“Rugger Jersey spine” due to hyperparathyroidism
How is renal bone disease treated?
- Vitamin D (alfacalcidol and calcitriol)
- Low phosphate diet
- Bisphosphonates for osteoporosis
Pathophysiology of anaemia in CKD?
kidneys produced EPO, which stimulates production of RBCs
CKD leads to less EPO and subsequent anaemia
Treatment of anaemia in CKD.
- Iron
- Exogenous EPO
Treatment of metabolic acidosis in CKD?
Oral sodium bicarbonate
Treatment of end stage renal failure?
- Dialysis
- Transplant
Treatment of hypertension in CKD?
ACE inhibitors: Monitor serum K+ as CKD and ACEi both cause hyperkalaemia
Criteria for ACEi:
- Diabetes plus ACR > 3mg/mmol
- Hypertension plus ACR > 30mg/mmol
- All patients with ACR > 70mg/mmol
What BP do we aim for in a patient with CKD?
< 140/90
