Aetiology with respect to frequency

Commonest cause:

• urinary tract infection

also common:

• renal tract stones

Less common causes:

• renal trauma and infarction
• benign prostatic hypertrophy
• benign microscopic haematuria
• glomerulonephritis
• malignant hypertension
• bleeding diathesis (anticoagulant treatment)
• ulcer at the urethral meatus

Uncommon causes:

• hydronephrosis
• polycystic disease
• transitional cell carcinoma
• renal adenocarcinoma or Wilm's tumour

Rare causes:

• polyarteritis nodosa, SLE, vasculitis, infective endocarditis
• atrial fibrillation - microemboli settling in the kidneys