What are the causes of hematuria?

Causes of Hematuria

Hematuria arises from urologic, glomerular, or systemic causes, with malignancy being the most critical diagnosis to exclude—particularly in adults over 35 years with gross hematuria, where cancer risk reaches 30-40%. 1, 2

Urologic Causes (Most Common in Adults)

Malignancies

• Bladder cancer is the most frequently diagnosed malignancy in hematuria cases, accounting for 30-40% of gross hematuria and 2.6-4% of microscopic hematuria 1, 2
• Renal cell carcinoma and upper urinary tract urothelial carcinoma are additional malignant causes requiring urgent evaluation 1, 3
• Risk factors include male gender, age >35 years, smoking (especially >30 pack-years), and occupational exposure to chemicals/dyes 1, 2

Benign Urologic Conditions

• Urinary tract infection presents with white cells and micro-organisms in urine, causing both microscopic and macroscopic hematuria 4, 1, 2
• Urolithiasis (kidney and ureteric stones) typically causes painful hematuria with flank pain, often associated with hypercalciuria 4, 1, 2
• Benign prostatic hyperplasia (BPH) is a common cause of hematuria in older men 1, 5, 2
• Trauma to kidneys or lower urinary tract from injury or foreign body insertion 4, 1

Glomerular/Renal Causes

Clinical Presentation

• Tea-colored urine accompanied by proteinuria (>2+ by dipstick), red blood cell casts, and dysmorphic red blood cells (>80% dysmorphic) strongly suggests glomerular disease 4, 1, 2

Specific Glomerular Diseases

• IgA nephropathy (Berger disease) is the most common glomerular cause of persistent isolated microscopic hematuria 4, 5, 2
• Post-infectious glomerulonephritis following streptococcal throat infection 4, 1, 2
• Alport syndrome presents with hematuria, progressive kidney disease, hearing loss, and ocular abnormalities requiring audiogram and slit lamp examination 4, 1, 5, 2
• Thin basement membrane nephropathy is an autosomal dominant condition causing asymptomatic hematuria, usually with benign course 1, 5
• Lupus nephritis and vasculitis (including Henoch-Schönlein purpura) 4, 1

Systemic and Other Causes

Hematologic Disorders

• Coagulopathies including hemophilia cause hematuria due to bleeding disorders 4, 1, 2
• Sickle cell disease causes hematuria through renal papillary necrosis 4, 1, 2
• Anticoagulants and antiplatelet agents may unmask underlying pathology but do not themselves cause hematuria—evaluation should never be deferred 1, 2

Benign Transient Causes

• Vigorous exercise causes transient hematuria that resolves with rest 1, 5, 2
• Menstruation can contaminate urine samples in women, leading to false-positive results 1
• Strenuous exertion and tropical exposure 4

Factitious Causes

• Food substances or medicines coloring urine without actual red blood cells (e.g., beets, rifampin) should be excluded 4

Age-Specific Considerations

Pediatric Population

• Glomerulonephritis and congenital anomalies are the most common causes in children 1, 2
• Asymptomatic microscopic hematuria (≥5 RBCs per high-powered field) has an incidence of 0.25-1.0% in children aged 6-15 years 4
• Consider recent strep throat, bloody diarrhea, joint pains, rash, family history of sickle cell disease, hemophilia, stone disease, hearing loss, or familial renal disease 4

Adult Population

• Malignancy risk increases significantly with age, particularly over 35-40 years 1, 2
• Men have higher risk than women across all age groups 1

Critical Clinical Pearls

Gross hematuria should never be ignored and requires urgent urologic referral even if self-limited, as it carries a 30-40% malignancy risk 1, 2. In contrast, microscopic hematuria most commonly has benign causes with only 2.6-4% malignancy risk 1, 6. However, approximately 20% of all hematuria patients have a urological tumor, with another 20% having significant underlying pathology 7.

Dipstick positivity must be confirmed with microscopic analysis showing ≥3 RBCs per high-power field before initiating full workup, as dipstick specificity is only 65-99% 1. Glomerular bleeding is characterized by >80% dysmorphic RBCs, while lower urinary tract bleeding shows >80% normal RBCs 1, 2.