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Hematuria is the presence of red blood cells (erythrocytes) in the urine. It may be idiopathic or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract (kidneys, ureters, urinary bladder, prostate, and urethra), ranging from trivial to lethal. If white blood cells are found in addition to red blood cells, then it is a signal of urinary tract infection.
Red discoloration of the urine can have various causes:
- Red blood cells
- Hemoglobin (only the red pigment, not the red blood cells)
- Other pigments
Sometimes the cause of hematuria can be elucidated solely on the basis of the medical history and urine testing, or urinalysis. This is especially true for young people, in whom the risk of malignancy is very low. For example, in a young woman who is found to have hematuria along with a simple urinary tract infection, she likely only needs antibiotics for her UTI, and does not need further workup for her hematuria. Similarly, high-intensity exercise can occasionally cause hematuria. As such, an athlete with blood in their urine after vigorous exercise usually just needs a repeat urine test.
For patients with suspected kidney stones, a common cause of hematuria, CT scanning or Ultrasound is often the first step. For most other patients with continued, unexplained hematuria, because of the risk of cancer of the bladder, prostate, ureters, or kidney is a concern, further imaging is usually done. This includes directly looking at the urethra and bladder with cystoscopy and more sensitive radiographic imaging with computed tomography urography.
The most common causes of hematuria are:
- Urinary tract infection with bacteria. The vast majority of UTIs are caused by Escherichia coli, with a smaller percentage due to Klebsiella pneumonia and Staphylococcus saprophyticus
- Nephrolithiasis: stones in the kidney, bladder or ureter
- Polycystic kidney disease
- Cancer of the kidney, prostate or bladder
- Benign prostatic hyperplasia, in older men, especially those over 50
- Indwelling urinary catheter
- Vigorous exercise
- No cause found
Other, less common causes of hematuria include:
- Glomerular bleeding: e.g.: IgA nephropathy ("Berger's disease"), Alport syndrome, thin basement membrane disease
- Sickle cell disease
- Schistosomiasis (caused by Schistosoma haematobium) - a major cause for hematuria in many African and Middle-Eastern countries
- Recent instrumentation of the urinary tract
- Kidney diseases
- Arteriovenous malformation of the kidney (rare, but may impress like renal cell carcinoma on scans as both are highly vascular)
Rare causes include:
- Paroxysmal nocturnal hemoglobinuria - a rare disease where hemoglobin of hemolyzed cells is passed into the urine
- Fibrinoid necrosis of the Glomeruli (as a result of malignant hypertension)
- Vesical varices may rarely develop secondary to obstruction of the inferior vena cava
- Allergy may rarely cause episodic gross hematuria in children
- Left renal vein hypertension, also called "nutcracker phenomenon" or "nutcracker syndrome," is a rare vascular abnormality responsible for gross hematuria
- Ureteral Pelvic Junction Obstruction (UPJ) is a rare condition beginning from birth in which the ureter is blocked between the kidney and bladder. This condition may cause blood in the urine
- March hematuria secondary to repetitive impacts on the body, usually the feet
- Athletic nephritis secondary to strenuous exercise
- Alport syndrome
Others signs that resemble hematuria include:
- Medications can cause red discoloration of the urine, but not hematuria. Some examples include: sulfonamides, quinine, rifampin, phenytoin
- consumption of beets ("beeturia")
- Jones (April 1997). "Sport-related hematuria: a review.". Clinical Journal of Sports Medicine. 7 (2): 119–125. PMID 9113428.
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- "Etiology and evaluation of hematuria in adults".
- Norman L. Browse/4th/436
- Hematuria Causes Original Date of Publication: 15 Jun 1998. Reviewed by: Stacy J. Childs, M.D., Stanley J. Swierzewski, III, M.D. Last Reviewed: 10 Jul 2008
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- Graham, DM.; McMorris, MS.; Flynn, JT. (Nov 2002). "Episodic gross hematuria in association with allergy symptoms in a child.". Clin Nephrol. 58 (5): 389–92. PMID 12425491. doi:10.5414/cnp58389.
- Russo, D.; Minutolo, R.; Iaccarino, V.; Andreucci, M.; Capuano, A.; Savino, FA. (Sep 1998). "Gross hematuria of uncommon origin: the nutcracker syndrome.". Am J Kidney Dis. 32 (3): E3. PMID 10074588. doi:10.1053/ajkd.1998.v32.pm10074588.
- Ureteral Pelvic Junction Obstruction (UPJ) / Ureteral Obstruction
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