Description

Blood or RBCs in the urine:

• Gross (visible) or microscopic (nonvisible)
• Symptomatic or asymptomatic

Epidemiology

• Microscopic hematuria in school-aged children: 0.5–2%
• Microscopic hematuria in asymptomatic adults varies from 0.19–21%, depending on population studied (1,2).

Risk Factors

• Smoking
• Occupational exposures (dyes, rubber or tire manufacturing)
• Analgesic abuse (e.g., phenacetin)
• Medications (e.g., cyclophosphamide)
• Pelvic irradiation
• Chronic infection, especially with calculi
• Recent upper respiratory tract infection
• Positive family history of renal diseases (stones, glomerulonephritis)
• Underlying primary renal disorder

Etiology

• Trauma:
  • Exercise-induced (resolves with rest)
  • Abdominal trauma or pelvic fracture with renal, bladder, or ureteral injury
  • Iatrogenic from abdominal or pelvic surgery; chronic indwelling catheters
  • Foreign body, physical/sexual abuse
• Neoplasms:
  • Malignancies: 30% of adult patients with painless, gross hematuria and ~10% with painless microscopic hematuria have a malignancy (1).
  • Benign tumors
  • Endometriosis of the urinary tract (suspect in females with cyclic hematuria)
• Inflammatory causes:
  • UTI: Most common cause of hematuria in adults
  • Renal diseases: Radiation nephritis and cystitis, acute/chronic tubulointerstitial nephritis (due to drugs, infections, systemic disease)
  • Glomerular disease:
    • Goodpasture syndrome (antiglomerular basement membrane disease; autoimmune; associated pulmonary hemorrhage)
    • IGA nephropathy
    • Lupus nephritis
    • Henoch-Schönlein purpura
    • Membranoproliferative, poststreptococcal, or rapidly progressive glomerulonephritis
    • Wegener granulomatosis
  • Endocarditis/Visceral abscesses
  • Other infections: Schistosomiasis, TB, syphilis
• Metabolic causes:
  • Stones (85% have hematuria):
    • Hypercalciuria: A common cause of both gross and microscopic hematuria in children
    • Hyperuricosuria
• Congenital/Familial causes:
  • Cystic disease: Polycystic kidney disease, solitary renal cyst
  • Benign familial hematuria or thin basement membrane nephropathy (autosomal dominant)
  • Alport syndrome (X-linked in 85%; hematuria, proteinuria, hearing loss, corneal abnormalities) (3)
  • Fabry disease (X-linked recessive inborn error of metabolism; vascular kidney disease)
  • Nail-patella syndrome (autosomal dominant; nail and patella hypoplasia; hematuria in 33%)
  • Renal tubular acidosis type 1 (autosomal dominant or autoimmune)
• Hematologic causes:
  • Bleeding dyscrasias (e.g., hemophilia)
  • Sickle cell anemia/trait (renal papillary necrosis)
• Vascular causes:
  • Hemangioma
  • Arteriovenous malformations (rare)
  • Nutcracker syndrome: Compression of left renal vein and subsequent renal parenchymal congestion
  • Renal artery/vein thrombosis
  • Arterial emboli to kidney
• Chemical causes:
  • Nephrotoxins: Aminoglycosides, cyclosporine
  • Other drugs: Analgesics, oral contraceptives, Chinese herbs
• Obstruction:
  • Strictures or posterior urethral valves
  • Hydronephrosis from any cause
  • Benign prostatic hyperplasia: Rule out other causes of hematuria.
• Other causes: Loin pain hematuria (most often in young women on oral contraceptives)