Renal Flashcards
What are the usual presenting compliants for urinary problems?
Obstructive:
- poor flow
- hesitancy
- intermittency
- terminal dribbling
Irritative:
- frequency
- urgency
- nocturia
- incontinence
What are some causes of urinary dysfunction?
Obstructive:
- BPH
- Ca prostate
- stricture
Irritative:
- seconday to obstruction
- UTI
- Ca bladder
- stone
- diabetes
- TB
What is the definition of acute urinary retention?
Sudden and painful inability to pass urine.
What are the causes and precipitants of acute urinary retention in males?
Causes:
- BPH
- prostate cancer
- stricture
- neurological (stroke, PD, acute spinal cord injury)
Acute precipitants:
- UTI
- diuresis
- constipation
- drugs
- postoperaive
- bleeding (clot retention)
What are the causes of acute urinary retention in females?
Reflex AUR:
- urethritis
- UTI
Intrinsic compression:
- meatal stenosis or stricture
- tumour
- urethral diverticulum or stone
Extrinsic compression:
- severe prolapse
- pelvic space-occupying lesion
What are the main physiological roles of the kidney?
- Maintain salt and water balance
- Excrete solutes and waste products
- Acid/base homeostasis
- EPO and Vitamin D
What are the features of kidney disease?
- Inability to excrete OR conserve salt and water
- Accumulation of solutes and waste products
- Accumulation of acids
- Anaemia and renal bone disease
What are the causes of acute kidney injury?
Pre-renal causes:
- haemorrhage
- hypovolaemia
- hypotension
Intra-renal:
- tubular injury (common) - ischaemia/prolonged hypoperfusion (ATN) or toxins
- interstitial nephritis (common) - drugs, infection, infiltration
- glomerular injury (uncommon) - inflammation (i.e. glomerulonephritis), thrombosis
- vascular disease (uncommon) - inflammation (vasculitis), occlusion (thrombosis or embolism)
Post-renal:
- tumour
- kidney stones
- enlarged prostate
- trauma
What are the three key assessments in the clinical assessment of AKIs?
- volume status to detect pre-renal cause
- urine studies to differentiate between pre-renal cause and ATN
- renal ultrasound to detect post-renal cause
Note: if pre-renal cause, urine will be concentrated (high Na). If ATN, urine will not be concentrated.
What is the definition of acute kidney injury?
Rapid decrease in kidney function over 48 hours
OR urine output less than 0.5 mL/kg/hour over 6 hours
What is the most common cause of acute kidney injury in the community and in hospitalised patients?
In the community, pre-renal AKI is the most common with obstruction (ureteric, bladder neck or urethral) the 2nd most common.
In hospitalised patients, pre-renal AKI is the most common.
What is the pathophysiology of acute tubular necrosis (ATN)?
Ischaemic depletion of ATP > release of ROS > apoptosis > cell desquamination > obstructive casts > back-leak of tubular fluid > reversible with regeneration of tubular endothelial cells
What are the three main clinical stages of acute tubular necrosis (ATN)?
- Initiation phase: acute decrease in GFR to low or very low levels, an increase in serum Cr and urea
- Maintenance phase: sustained reduction in GFR - urea and Cr continue to rise
- Recovery phase: tubular function is restored with increase in urine volume (if oliguria was present) and a gradual decrease in Cr and urea.
What are some considerations in the clinical evaluation of AKI?
- Is the renal impairment acute or chronic?
- Has obstruction been excluded? (often complete anuria with palpable bladder, renal U/S shows hydronephrosis)
- What is the patient’s volume status? (may suggest pre-renal)
- Is there evidence of other intrinsic renal disease apart from ATN? (history, exam, urinalysis)
- Has a major vascular occlusion occurred? (history and risk factors)
What are some risk factors for acute kidney injury?
Background:
Elderly, CKD, cardiac failure liver disease, diabetes, vascular disease, background nephrotoxic medications
Acute insult:
Sepsis and hypoperfusion, toxicity, obstruction, parenchymal kidney disease
