Acute Kidney Failure Flashcards
Broad categories of AKF aetiologies
Pre-renal
Intrinsic (renal)
Post-renal
Pre-renal causes of AKF
Decreased blood flow to kidney –> Renal ischaemia
- Hypovolemia
- Hypotension
- HF
- Liver cirrhosis –> hepatorenal syndrome
- Renal artery stenosis
- Renal vein thrombosis (can’t drain properly –> stasis –> ischaemia)
Classic lab findings in pre-renal AKF
Orine osmolarity: >500
Urine Na+: 20
Intrinsic (renal) causes of AKF
Damage to glomeruli, renal tubules, or interstitium due to:
- Glomerulonephritis –> damage to glomeruli
- Acute tubular necrosis –> damage to renal tubues
- Acute interstitial nephritis –> damage to interstitium
Other causes:
- Rhabdomyolysis
- Tumour lysis syndrome
Features of Nephrotic syndrome
- Oedema
- Proteinuria
- Hypoalbuminaemia (serum)
Features of Nephritic Syndrome
- Haematuria
- HTN
- Oliguria
Types of glomerulonephritis
- Minimal change disease
- Focal segmental glomerulosclerosis
- Membranous glomerulonephritis
- Thin basement membrane disease
Features of minimal change disease
- Presents as nephrotic syndrome
- Tx with corticosteroids, does not progress to chronic kidney disease
Features of Focal segmental glomeruloscleross
- Affects glomeruli - segments of sclerosis
- Increased hyaline, homogenous pink, seen on EM
- Associated with HIV, Heroin abuse, or inherited Alport’s Syndrome
- 20-30% cases unknown cause
- 50% patients progress to total renal failure
- Tx: corticosteroids
Features of Membranous glomerulonephritis
- Presents as nephrotic OR nephritic syndrome
- Usually associated with auto-antibodies to phospholipase A2 receptors
- Other associations include: SLE, malaria, Hep B, bowel and lung cancers, Penicillamine
- Prognosis: rule of thirds
- — 1/3 patients remain with MGN indefinitely
- — 1/3 remit
- — 1/3 progress to total renal failure
Thin basement membrane disease
- Inherited condition, AD
- Thin glomerular basement membrane seen on EM
- Benign condition
- Causes persistent microscopic haematuria, +/- mild proteinuria
- Good prognosis
Key causes of intrinsic renal failure, of glomerular origin?
- Minimal change disease
- Focal segmental glomerulosclerosis
- Membranous glomerulonephritis
- Thin basement membrane disease
Features of Acute Tubular Necrosis
- Necrosis of the epithelial cells forming the renal tubules
- One of the most common causes of ARF
- Causes: HTN, nephrotixicity (usually drugs)
- Presence of “muddy brown casts” of epithelial cells = pathognomonic for ATN
- Tx is of underlying cause
- Because of usual rapid turnover of epithelial cells of renal tubules, once underlying cause treated, recovery usually within 7-21 days
Common nephrotixic drugs causing direct renal tubule injury
Proximal tubule
- Gentamycin (Aminoglycoside Abx)
- Amphotericin B
- Cisplatin
- Radiocontrast media
- Immunoglobulins
- Mannitol
Distal tubule - NSAIDs - ACEIs - Cyclosporins Litium salts - Cyclophosphamide - Amphoteracin B
Tubular obstruction
- Sulphonamides
- Methotrexate
- Aciclovir
- Triamterene
- Diethylene
Features of Interstitial Nephritis
- Nephrtis affecting the interstitium surrounding renal tubules
- Common causes: Infection, drug reactions (most cases)
- Time delay from exposure to offending drug - development of interstitial nephritis can be 5/7 to 5/12
- Symptoms: sometimes asymptomatic
- Varied: Dysurua, electrolyte imbalances, metabolic acidosis, lower back pain
- Allergic reaction type: fever, rash, enlarged kidneys
- Chronic IN: Nausea, vomiting, fatigue, w/loss, electrolyte imbalances
- Tx: remove offending agent, ensure hydration
- Chronic type: No cure, will progress to ARF –> dialysis –> renal transplant
