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Hematuria refers to blood in the urine. At times, the diagnosis of hematuria is clear, such as when the urine appears pink or red or when blood clots are observed in the urine.
Other times, the diagnosis of hematuria is made only after a microscopic evaluation of the urine (urinalysis). Usually, less than three red blood cells can be seen per high-power field during a microscopic examination.
Any finding of blood in the urine warrants medical evaluation. (1)
What are the types of hematuria?
Hematuria is classified into two categories:
- Gross hematuria: Red blood cells in the urine cause the color of the voided urine to appear brown (“cola-colored”), pink, or red. It takes only a small amount of blood in the urine to make the urine appear pink or red. (2)
- Microscopic hematuria: This is diagnosed when three or more red blood cells are identified per high-power field on a properly collected urine sample in the absence of an obvious benign cause. (3)
What are the causes of hematuria?
Hematuria can arise from anywhere within the urinary tract: the kidneys, ureters (tubes that drain the kidneys into the bladder), bladder, prostate, or urethra. (4)
The causes of hematuria include:
- Benign causes: These include infections (UTI, prostatitis), enlarged prostate (BPH), trauma, vigorous exercise, kidney stones, or viral illnesses. Sometimes menstruation can be confused as hematuria.
- Serious causes: Cancer of the kidney, ureter, bladder, prostate, or urethra are the most serious causes of hematuria. Other causes include medical renal (kidney) disease or nephritis, hemophilia, clotting disorders, and polycystic kidney disease. Radiation cystitis or chemotherapy cystitis can occur following radiotherapy or chemotherapy for malignancies.
Sometimes, hematuria is first identified after starting blood thinners for other reasons (aspirin, Coumadin, etc.). Even if hematuria begins after starting these medications, it is important to perform a full evaluation to identify the source of the hematuria.
What are the signs and symptoms of hematuria?
The symptoms of hematuria depend on its cause. Often, hematuria has no symptoms at all other than discolored urine or reports of blood found on urinalysis.
If hematuria is caused by a urinary tract infection (UTI) or kidney infection, it may be accompanied by fever, abdominal pain, or flank pain. UTIs can also be associated with dysuria (burning with urination), urinary frequency, increased urinary urgency, or pelvic pain.
If hematuria is caused by an enlarged prostate, it may be accompanied by slowing of the urinary stream, urinary frequency, and urgency, or a sense of incomplete emptying of the bladder.
Hematuria caused by kidney stones can be associated with a sharp pain in the flank radiating to the groin.
What are the risk factors for hematuria?
The risk factors for hematuria depend on the underlying cause. (5)
The biggest risk factor for urothelial cancers is tobacco use. Smoking increases the risk of bladder cancer by twofold to fourfold, and more frequent smoking and longer duration of smoking increase this risk.
Additional risk factors for urothelial cancer include chemical exposure (particularly exposure to aniline dye), chronic cystitis from either a catheter or recurrent urinary tract infections, radiation therapy, and certain medications.
The most common urinary stone in Western countries is calcium oxalate. Risk factors for this stone include dehydration, obesity, and diets high in protein or oxalate.
Although taking blood thinners can cause bleeding risks, they should not cause hematuria. All hematuria should be fully evaluated, even if it is discovered after starting new medications.
How is hematuria diagnosed and evaluated?
A full evaluation of hematuria begins with a visit to your doctor. Be prepared to discuss your entire medical history, any medications taken, and general health questions.
Any history of tobacco use, urinary infections, kidney stones, and trauma will be discussed. (6)
Dipstick urinalysis is insufficient to diagnose hematuria. A properly performed urinalysis with microscopic evaluation of the urine is recommended to determine the composition of blood and protein in urine specimens.
A metabolic panel will be performed to evaluate kidney health and function. Further tests may be ordered depending on the results of these laboratory evaluations.
For all patients over the age of 35, a cystoscopic examination is recommended for direct visualization of the urethra, prostate, and bladder.
Evaluation of the upper urinary tract with contrast-enhanced CT scan or MRI is recommended. Special attention in these exams is paid to the kidneys, ureters, and bladder to rule out any anatomic irregularity or malignancy. If a lesion is found, other tests may be indicated.
Can hematuria increase the risk of cancer?
Painless hematuria can be associated with cancer in the kidney, ureter, bladder, prostate, or urethra, and it is important to see a physician right away for a full evaluation. (7)
Urologic cancers are found in approximately 1 in 4 patients with gross hematuria and around 1 in 20 patients with microscopic hematuria. Up to 1 in 10 patients with gross hematuria have no clear etiology (cause) on full evaluation, and nearly 20% of these patients ultimately develop urologic cancer.
Nearly half of patients with microscopic hematuria have no clear etiology on full evaluation, and up to 3% of these patients are ultimately found to have urologic malignancy diagnosed in the future. For these reasons, repeat anatomic evaluation is recommended within 3-5 years if no etiology is determined on initial evaluation and hematuria persists.
What is the treatment for hematuria?
The treatment of hematuria is dictated by its underlying cause. If no cause is found for hematuria, no treatment is needed. Repeat laboratory or imaging studies may be required in the future. (8)
If hematuria is caused by infection, administration of antibiotics is curative. If hematuria is caused by nephritis or renal disease, certain medications and diet may be prescribed.
Urinary calculi causing hematuria can be treated with either medical or surgical management, depending on the size, makeup, and location of the stone.
If hematuria is caused by a urologic malignancy, medical and surgical treatments will need to be completed. If discovered early and treated appropriately, many urologic malignancies can be cured.
What type of food can control hematuria?
There are no studies that show a direct link between diet and hematuria. Some foods, including beets, fava beans, blueberries, and rhubarb, can cause the urine to appear red. This is not hematuria but can be confused with hematuria.
Sometimes, acidic foods (wine, coffee, spicy foods) can cause irritation to the bladder in patients with a condition known as interstitial cystitis. There are no links between these foods or drinks and hematuria.
What home remedies and self-care measures can be done to avoid hematuria?
All types of hematuria need to be evaluated thoroughly.
Sometimes, hematuria begins as intermittent discoloration or reddening of the urine. Even if gross hematuria appears to go away, that does not mean that a full evaluation can be avoided.
If you experience hematuria, it is important to hydrate well to flush the urinary system. Discuss hydration volume goals with your doctor after discussing all of your medical conditions.