L79: Renal Failure: Common Causes, Clinical Features And Complications

Question 1

Kidney dysfunction

Answer 1

Acute / Chronic

Cause: Pre-renal / Intra-renal / Post-renal

Question 2

Chronic kidney disease and stages

Answer 2

Normal GFR: 100-125 ml/min/1.73m^2
- Decline by 1 per year

K/DOQI classification of CKD stages:
Stage 1: >=90
Stage 2: 60-90
Stage 3: 30-60
Stage 4: 15-30
Stage 5: <15

Question 3

Pre-renal causes of kidney dysfunction

Answer 3

1. Hypoperfusion
   - hypovolemia
   - septic / cardiogenic shock
2. Renovascular disease
   - renal artery stenosis
   - thrombosis

Question 4

Intra-renal causes of kidney dysfunction

Answer 4

1. Drugs
   - NSAIDs
   - Antimicrobials (aminoglycoside, adefovir, penicillin (AIN))
   - Iodine contrast
2. Glomerulonephritis (Nephrotic vs Nephritic, Primary vs Secondary)
   - DM nephropathy (most common cause of ESRD), Type I (early onset), Type 2 (late onset)
   - Hypertension nephrosclerosis
   - Hereditary (Alport syndrome, Autosomal dominant polycystic kidney disease)
3. Acute tubular necrosis (Ischaemia: 3 phases)
   - Initiation phase (36 hours, ↓ urine, ↑ blood urea and creatinine)
   - Maintenance phase (oliguria, salt and water overload, hyperkalaemia, metabolic acidosis)
   - Recovery phase (steady ↑ urine, loss of large amount of water, Na, K —> may cause electrolyte imbalance) (Tubular epithelium can regenerate)
4. Acute / Chronic interstitial nephritis (Drugs)
   - withdrawal of drugs
   - Interstitial infiltrate (mononuclear cells + eosinophil)
   - Interstitial inflammation, oedema, fibrosis
   - Other causes: Infections (pyelonephritis), Metabolic diseases (uric acid nephropathy), Neoplasm (myeloma, light chain cast nephropathy)
5. Metabolic disease
6. Tubular obstruction (Light chain cast nephropathy, Rhabdomylosis, Crystallisation)
7. Infection

Question 5

Nephrotic vs Nephritic syndrome

Answer 5

Nephritic:

• renal impairment usually present
• ++ proteinuria
• ++ haematuria
• hypertension associated
  1. Post-infectious GN
  2. Anti-GBM (Goodpasture syndrome)
  3. ANCA-vasculitis
  4. IgA nephropathy
  5. Lupus nephritis

Nephrotic:

• +/- renal impairment
• +++ proteinuria
• +/- haematuria
• oedema, hyperlipidemia, hypoalbminemia
  1. Membranous nephropathy
  2. MPGN
  3. Minimal change disease
  4. FSGS
  5. Amyloidosis

Question 6

Glomerulonephritis diagnosis and treatment

Answer 6

1. Autoimmune marker, infection, malignancy screen
2. LM / IF / EM of renal biopsy

Treatment:

• general: ACEI/ARB
• specific: Immunosuppression

Question 7

Post-renal causes

Answer 7

1. Bilateral obstruction e.g. prostate problem
   - BPH —> bilateral hydronephrosis, weak stream, frequency, precipitated by UTI drugs, antimuscarinic drugs
   - CA prostate
2. Urethra
   - Urethral stenosis
   - lower UTI seldom
3. Urinary bladder
   - CA bladder: painless gross haematuria
   - Bladder stones: dysuria, haematuria, recurrent UTI
4. Ureter
   - extramural: metastatic lymph node, firbosis
   - intramural: CA ureter

Question 8

***Complications of renal failure

Answer 8

1. General
   - malaise
   - pruritis
   - nausea, vomiting
2. Urinary symptoms
   - polyuria, nocturia
3. Cardiovascular
   - oedema
   - hypertension
   - cardiomegaly
4. Neurological
   - restless leg
   - confusion, seizure
5. Haematological
   - normocytic normochromic anaemia
   - bleeding tendency
6. Endocrine
   - sexual dysfunction
   - growth retardation
   - hyperparathyroidism

• **7. Electrolyte and acid base imbalance
• Hyponatremia (↓ reabsorption)
• Hyperkalemia
• Metabolic acidosis (↑ anion gap)
• Hypocalcemia (1,25 dihydoxyvitamin D cannot produced by kidney)
• Hyperphosphatemia

Question 9

Management of renal failure

Answer 9

CKD:

• Underlying cause
• Dietary and lifestyle
• BP control
• Avoid nephrotoxic agents

ESRF:
- Renal replacement therapy:
—> haemodialysis
—> peritonealdialysis
—> renal transplant
- Palliative renal care