Background: Microscopic hematuria that is not explained by an obvious underlying condition is a frequent and often an incidental finding that commonly triggers urological or nephrological evaluation. Potential underlying conditions range from benign to severe malignant diseases of the kidneys and urinary tract.
Materials and methods: A nonsystematic literature search was performed, focusing on potential urological and nephrological causes of hematuria. National and international guidelines were considered and diagnostic as well as follow-up strategies are discussed. We provide a recommendation for practices in the clinical evaluation of hematuria.
Results: The overall prevalence for microscopic hematuria is estimated at approximately 2%, whereas risk populations show an increase to around 30%. In 13-35% of patients presenting with microscopic hematuria, a medical or surgical intervention is required. Malignant tumors of the kidneys or urinary tract can be diagnosed in 2.6-4% of all patients and in up to 25.8% of at-risk populations. "Idiopathic microscopic hematuria" without an obvious underlying medical condition accounts for approximately 80% of patients with asymptomatic hematuria. After exclusion of nephrological diseases, standard diagnostic procedures by means of medical history, physical and laboratory examination as well as ultrasound of the kidneys and the urinary tract should be performed. In the presence of risk factors, an extended diagnostic work-up using cystoscopy, urinary cytology, and cross-sectional imaging of the upper urinary tract is indicated.
Conclusion: Evidence-based strategies of a risk-adapted diagnostic evaluation for microscopic hematuria are not available. The development of reliable clinical and molecular markers offers great potential for the identification of patients at higher risk for harboring severe diseases.
Keywords: Early detection of cancer; Hematuria, glomerular; Neoplasms, urologic; Urinary bladder neoplasms; Urine analysis.