Hematuria
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Introduction
Red blood cells (RBCs) are not present in the urine of 95% of healthy individuals. If urine appears pink or red, false negatives should be ruled out (as discussed under urinalysis).
Extrarenal: blood clots in urine, or 3 glass test
The Case of...
Differential Diagnosis
Microscopic hematuria is defined as >2 RBCs per high powered field in centrifuged urine sediment. It is seen in up to 13% of the asymptomatic population, and is almost always incidental (Mohr et al, 1986).
Exercise-induced hematuria is common and can be both microscopic and macroscopic. It is seen in both contact and non contact sports. There are a variety of explanations, including ischemic damage, efferent arteriole vasoconstriction, or bladder trauma (Abarbanel et al, 1990). RBCs are seen in the urine, in contrast with rhabdomyolysis and march hemoglobinuria.
Hematuria can also be the first sign of intrinsic renal disease or malignancy. Blood can come from the kidney, GU tract, or urethra. More serious causes of hematuria are diverse, and include the following:
renal causes |
urological causes
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systemic causes
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History and Physical Exam
- history
- physical exam
History
Initial Investigations for hematuria include a thorough history and physical exam, with special attention paid to:
- onset and course of symptoms
- family history
- other medical history (connective tissue disease, sickle cell disease)
- any evidence of renal disease: abnormal renal function, proteinuria, hypertension
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Further investigations, in ascending order:
- protein:creatinine ratio should assessed if protein is positive on dipstick
- urine microscopy and culture: dysmorphic red blood cells suggest glomerular disease
- plasma biochemistry and eGFR
- autoantibody screen: ANA, ANCA, and complement levels
- renal ultrasound
- renal CT/MRI
- cytoscopy in adults >50: assess for urologic malignancy
- renal biopsy if absolute diagnosis is desired
Diagnostic Imaging
Management
Prognosis for asymptomatic microhematuria, without malignancy or evidence of renal disease, is very good. Good control of blood pressure (<130/80 mmHg) and reduction of (micro)proteinuria is very important to maintain kidney function. ACE inhibitors or ARBs are useful in addressing both. Further follow-up is required, with regular urinalysis, and monitoring of blood pressure and renal function.
Pathophysiology
Resources and References
Abarbanel J et al. 1990. Sports Hematuria. Journal of Urology. 143:887-890.
Mohr DN et al. 1986. Asymptomatic microhematuria and urologic disease. A population-based study. JAMA. 256:224-229.
Topic Development
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