Renal and Urology Flashcards
What is acute kidney injury (AKI)?
An acute decline in kidney function, leading to a rise in serum creatinine and/or a fall in urine output
What is the aetiology of acute kidney injury (AKI)?
Pre-renal, renal and post renal
AKI may be due to various insults such as:
- impaired kidney perfusion
- exposure to nephrotoxins
- outflow obstruction
- intrinsic kidney disease
What are the risk factors of acute kidney injury (AKI)?
Advanced age
Underlying kidney disease
DM
Sepsis: may result in ATN, pre-kidney AKI from hypotension
Nephrotoxins e.g. aminoglycosides, NSAIDs, vancomycin
What are the pre-renal causes of an AKI?
Reduced renal perfusion:
1. Shock (hypovolaemic, septic, cardiogenic)
2. Hepatorenal syndrome (liver failure)
What are the renal causes of an AKI?
- Acute tubular necrosis: ischaemia, drugs and toxins
- Acute glomerulonephritis
- Acute interstitial nephritis: NSAIDs, penicillins, sulphonamides
- Vessel obstruction:
- Renal artery/vein thrombosis
- Cholesterol emboli
- Vasculitis - Other causes: myeloma, haemolysis, nephropathy
What are the post renal causes of an AKI?
- Stone
- Tumour (pelvic, prostate, bladder)
- Blood clots
- Retroperitoneal fibrosis
What are the presenting symptoms of AKI?
Usually asymptomatic
Lower urinary tract symptoms:
- Urgency
- Frequency
- Hesitancy
Low urine output (oliguria)
Malaise
Anorexia
Nausea and vomiting
Pruritus (itching)
Drowsiness
Convulsions, coma (caused by uraemia)
What are the signs of acute kidney injury (AKI) on physical examination?
- Reduced urine output
- Pulmonary and peripheral oedema
- Arrhythmias (secondary to changes in potassium and acid-base balance)
- Features of uraemia (e.g. pericarditis or encephalopathy)
What are the appropriate investigations for AKI?
- U&Es: serum creatinine (rise of 26 micro mol/L in 48 hours or >50% in 7 days), potassium, sodium and urea
- Urinalysis: all suspected AKI patients, cellular casts (glomerulonephritis)
- Renal ultrasound: if no identifiable cause of deterioration or risk of obstruction
- ECG: changes associated with hyperkalaemia (tented T waves) and CXR
How do you assess a patient’s fluid status in an AKI?
Pulse rate
Lying and standing BP
JVP
Skin turgor
Chest auscultation
Peripheral oedema
Central venous pressure
Fluid and weight charts
ECG monitoring (hyperkalaemia)
What is the management for a patient with an AKI?
Largely supportive
1.Assess hydration and fluid balance: hypovolaemic or hypervolaemic
2. Review patient’s medications
3. Assess hyperkalaemia
How do you manage an hypovolaemic patient with an AKI?
- Fluid resuscitation
- Review medications and stop nephrotoxins
- Identify and treat underlying cause
How do you manage an hypervolaemic patient with an AKI?
- :Loop diuretic (NOT ROUTINE -under specialist supervision) and sodium restriction
- Identify and treat underlying cause
- Consider: renal replacement therapy
Which medications should be stopped in patients with an AKI?
- NSAIDs (except if aspirin at cardiac dose e.g. 75mg od)
- Aminoglycosides
- ACE inhibitors
- Angiotensin II receptor antagonists
- Diuretics
May have to stop: Metformin, lithium and digoxin
‘stop the DAMN drugs’: diuretics, ACEi, metformin and NSAIDs
What are some of the complications of an AKI and what would you switch to?
Hyperkalaemia
Pulmonary oedema
Acidosis or uraemia (e.g. pericarditis, encephalopathy)
Switch to renal replacement therapy e.g. haemodialysis
What is the management of hyperkalaemia?
Medical emergency!
1. Cardio protection: Intravenous calcium gluconate
2. Short term shift in potassium from extracellular to intracellular: Combined insulin/dextrose infusion and nebulised salbutamol
3. Removal of potassium from body: Calcium resonium (orally or enema), loop diuretics, finally dialysis
What is the treatment for acute pulmonary oedema?
P- positioning (sit up)
O- oxygen
D- diuretic (furosemide) and fluid restriction
M- (dia)morphine
A- anti-emetics
N- nitrates (GTN infusion if SBP >110, or 2 puffs GTN spray if SBP >90)
What is amyloidosis?
A (heterogenous) group of diseases characterised by extracellular deposition of insoluble amyloid fibrils
What are the two types of amyloidosis?
- AL amyloid = primary, immunoglobulin light chain amyloidosis, associated with Myeloma
- AA amyloid = secondary, non-familial and familial
Non- familial AA = Inflammatory polyarthropathies account for 60% of cases, then chronic infections, IBD
What are the risk factors for amyloidosis?
PMH of inflammatory conditions (AA)
Chronic infections (AA)
Positive FH
What are the renal features of primary amyloidosis (AL)?
Glomerular lesions—proteinuria and nephrotic syndrome
What are the renal features of secondary non-familial amyloidosis (AA)?
PMH of chronic inflammation (e.g. RA/ IBD) or chronic infection (e.g. TB)
May present with proteinuria, nephrotic syndrome, or hepatosplenomegaly
What are the appropriate investigations for amyloidosis?
Diagnosis made with biopsy of affected tissue: positive Congo Red staining with apple-green birefringence under polarized light microscopy
The rectum or subcutaneous fat are relatively non-invasive sites for biopsy and are positive in 80%
What is the management of amyloidosis?
AL: optimize nutrition; PO melphalan + prednisolone extends survival
High-dose IV melphalan with autologous stem cell transplantation may be better
AA: manage the underlying condition optimally