What are the causes of hematuria (blood in urine)?

Causes of Hematuria

Hematuria arises from urologic causes (malignancy, infection, stones, BPH, trauma), glomerular/renal causes (glomerulonephritis, IgA nephropathy, Alport syndrome, thin basement membrane disease), and systemic/other causes (vigorous exercise, coagulopathies, sickle cell disease), with malignancy accounting for 30-40% of gross hematuria cases and requiring urgent evaluation. 1

Urologic Causes

Malignancy is the most critical urologic cause to exclude:

• Bladder cancer is the most frequently diagnosed malignancy in hematuria cases, presenting classically as painless gross hematuria in 70-80% of patients 1, 2, 3
• Renal cell carcinoma represents upper tract malignancy 2
• Prostate cancer can produce hematuria with lower urinary tract symptoms 2
• Malignancy accounts for 30-40% of gross hematuria and 2.6-4% of microscopic hematuria, with risk factors including male gender, age >35 years, smoking >30 pack-years, and occupational chemical/dye exposure 1, 2

Benign urologic causes include:

• Benign prostatic hyperplasia (BPH) is the most common benign urologic cause in men, particularly over age 50 1, 4, 2
• Urinary tract infection causes both microscopic and macroscopic hematuria with pyuria and bacteriuria 1, 4, 2
• Urolithiasis (kidney/ureteric stones) typically causes painful hematuria with flank pain 1, 4, 2
• Trauma to kidneys or lower urinary tract 1

Glomerular/Renal Causes

Primary glomerular diseases:

• IgA nephropathy (Berger disease) is a common cause of persistent isolated microscopic hematuria 4
• Post-infectious glomerulonephritis 1
• Thin basement membrane nephropathy is an autosomal dominant condition causing asymptomatic hematuria, usually with benign course but can progress to chronic kidney disease 1, 4
• Alport syndrome is hereditary nephritis with associated hearing loss 1, 4

Secondary renal causes:

• Lupus nephritis and vasculitis 1
• Interstitial renal disease, including drug-induced or analgesic nephropathy 4
• Renal parenchymal disease is the most common benign nephrogenic cause 1, 4

Clinical clue: Tea-colored urine suggests glomerular source, with >80% dysmorphic RBCs, RBC casts, and significant proteinuria indicating glomerular bleeding 1, 4

Systemic and Other Causes

Hematologic disorders:

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

Transient/benign causes:

• Vigorous exercise causes transient hematuria that resolves with rest 1, 4
• Menstruation can contaminate urine samples in women, causing false-positive results 1
• Hypercalciuria and hyperuricosuria may be associated with microscopic hematuria 4

Age-Specific Considerations

Children:

• Glomerulonephritis and congenital anomalies are most common 1

Adults:

• Malignancy becomes significant risk factor, especially over age 35 1
• Men have higher malignancy risk than women, with risk stratification: men <40 years (low risk), 40-59 years (intermediate), ≥60 years (high risk) 1

Critical Clinical Pitfalls to Avoid

• Never ignore gross hematuria—it requires urgent urologic referral even if self-limited, given 30-40% malignancy association 1, 2
• Anticoagulation is not a reason to forgo evaluation—these medications unmask rather than cause hematuria 1, 2
• Confirm dipstick positivity with microscopic analysis showing ≥3 RBCs per high-power field before initiating workup, as dipstick has limited specificity (65-99%) 1
• Suspect tumor until proven otherwise in all visible hematuria cases 3
• In approximately 80% of asymptomatic microscopic hematuria cases, no cause is ever found (idiopathic) 4