In medicine, hematuria, or haematuria, is the presence of red blood cells (erythrocytes) in the urine. It may be idiopathic and/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.
Occasionally "hemoglobinuria" is used synonymously, although more precisely it refers only to hemoglobin in the urine.
Red discoloration of the urine can have various causes:
Red blood cells
Microscopic hematuria (small amounts of blood, can be seen only on urinalysis or light microscopy)
Macroscopic hematuria (or "frank" or "gross" hematuria)
Hemoglobin (only the red pigment, not the red blood cells)
Other pigments
Myoglobin in myoglobinuria
Porphyrins in porphyria
Betanin, after eating beets
Drugs such as rifampicin, phenazopyridine and sulphonamides
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.
If combined with flank pain, loin pain hematuria syndrome is a rare but possible cause.
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
Trauma
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
Prostatitis
Urethritis
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")
menstruation
