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Hematuria and Microhematuria: Causes and Diagnosis

Definition of Hematuria and Microhematuria

Hematuria is defined as visible blood in urine; microhematuria is defined with more than 5 erythrocytes per high power field. More than 20 erythrocytes per high power field is a strong microhematuria. Medical history and urine analysis are cornerstones for planning rational further imaging and endoscopic diagnosis:

Differential Diagnosis of Hematuria and Microhematuria

Abnormal Urine Color

Abnormal urine color can simulate hematuria, microscopic examination of the urine shows no blood cells.

• Food: beetroot ("beeturia"), blueberry, blackberry
• Myoglobinuria
• Chronic lead poisoning
• Medication with rifampicin

Glomerular Hematuria

Examination of the urine shows deformed (dysmorphic) red blood cells, red blood cell casts and proteinuria.

• IgA nephropathy
• Various forms of glomerulonephritis
• Alport's syndrome
• Systemic lupus erythematosus
• Subacute bacterial endocarditis

Non-glomerular Hematuria

Examination of the urine shows circular red blood cells and frequently proteinuria (especially in systemic diseases and medical renal diseases). Initial hematuria is a sign for diseases of the urethra or prostate. Terminal hematuria is often caused by diseases of the bladder trigone.

• Systemic diseases:
  • Hemophilia
  • Thrombocytopenia
  • Disseminated intravascular coagulation
  • Medication: anticoagulation, platelet aggregation inhibitors.
• Kidney diseases:
  • Urolithiasis
  • Cystic kidney diseases (e.g., autosomal dominant polycystic kidney disease, medullary sponge kidney, simple kidney cyst)
  • Papillary necrosis (e.g., sickle cell disease, abuse of analgesics, diabetes mellitus)
  • Renal artery embolism or renal vein thrombosis
  • Tumors
  • Renal arteriovenous fistula or malformation
  • Nephrolithiasis
  • Infections
• Lower urinary tract:
  • Infections
  • Tumors: e.g., bladder cancer, female urethral cancer, male urethral cancer, prostate carcinoma.
  • BPH: bladder stones, varicose veins of the prostate
  • Radiation cystitis
• Other causes of hematuria: exercise-induced hematuria, benign familial hematuria.

Diagnostic Workup of Hematuria

Basic Workup of Hematuria

• Urine analysis with microscopic examination
• Labatory tests: blood count, coagulation tests (PTT, PT) and creatinine
• Ultrasound imaging of kidneys and full urinary bladder
• Intravenous urography or computer tomography of the abdomen (CT urography)
• Cystoscopy

Further studies in Hematuria

• CT Urography: indicated for suspected tumors or with pathologic intravenous urography. Best imaging of the kidney is achieved with a high-resolution multidetector CT scanner and using multiple contrast phases.
• Urine cytology: indicated in persisting hematuria and a basic workup with no pathologic findings
• MRI Urography: indicated as an alternative to CT Urography, e.g., due allergy to iodinated contrast medium or for children.
• Retrograde pyelography and ureteroscopy: indicated in suspected diseases of the ureter or renal pelvis.
• Angiography: to identify suspected arteriovenous fistula or diseases of the renal artery or vein
• Renal biopsy: indicated in suspected medical renal diseases (e.g., glomerulonephritis).

References

  Deutsche Version: Hämaturie

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