Causes of Microscopic Hematuria
Microscopic hematuria has diverse etiologies ranging from benign conditions to potentially life-threatening malignancies, with glomerular disease being the most common benign nephrogenic cause. 1
Common Causes of Microscopic Hematuria
Urologic Causes
- Urinary tract infections - most common benign cause 1, 2
- Benign prostatic hyperplasia - particularly in older men 2
- Urolithiasis (kidney stones) 1, 2
- Urinary tract malignancies - risk increases with age >35 years, smoking history, male gender 1, 2
- Trauma 1
- Recent urologic procedures 1
- Vigorous exercise - transient finding 1
Glomerular Causes
- Glomerulonephritis - various forms 1
- IgA nephropathy (Berger disease) 3, 1
- Thin basement membrane nephropathy - most common cause of progressive chronic kidney disease 3, 1
- Alport syndrome 3, 1
- Post-streptococcal glomerulonephritis - especially in children 3, 1
- Henoch-Schönlein purpura 3, 1
Systemic Conditions
Metabolic Causes
Medication-Related
- Analgesic abuse 1
- Anticoagulant therapy - note that this should not be assumed as the cause without further evaluation 1, 4
Risk Factors for Malignancy in Patients with Microscopic Hematuria
- Male gender
- Age >35 years (risk increases with age, particularly >60 years)
- Smoking history
- Occupational exposure to chemicals
- History of pelvic irradiation
- Chronic urinary tract infection
- Chronic indwelling foreign body
- Analgesic abuse 1
Special Considerations
In Children
- Asymptomatic microscopic hematuria without proteinuria rarely indicates significant renal disease 3, 1
- Family history screening may identify benign familial hematuria 3, 1
- Consider causes specific to children such as post-streptococcal glomerulonephritis and Henoch-Schönlein purpura 3, 1
Important Distinctions
- Glomerular vs. Non-glomerular Hematuria: The presence of dysmorphic red blood cells, red cell casts, and proteinuria suggests glomerular origin 5
- Isolated vs. Non-isolated Hematuria: Presence of proteinuria, hypertension, or elevated creatinine alongside hematuria suggests more significant renal disease 2
Common Pitfalls in Evaluation
- Relying solely on dipstick testing without microscopic confirmation 1
- Failing to repeat urinalysis after treating a presumed cause 1
- Assuming anticoagulant therapy is the cause without further evaluation 1, 4
- Inadequate evaluation of persistent microscopic hematuria 1
- Overlooking the possibility of malignancy (up to 5% of patients with asymptomatic microscopic hematuria may have urinary tract malignancy) 2
Remember that microscopic hematuria, defined as ≥3 red blood cells per high-power field on microscopic examination from two of three properly collected specimens 1, should always prompt appropriate evaluation to identify the underlying cause, even when asymptomatic.