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What is Blood in Urine (Hematuria)?
Hematuria is the medical term used to describe the presence of blood in the urine. This condition can present in two distinct forms:
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Gross hematuria (macroscopic hematuria), when the patient can visually notice blood in the urine, often causing the urine to appear pink, red, or brown.
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Microscopic hematuria, when blood cells are present in the urine but in quantities too small to be seen with the naked eye, and can only be detected through laboratory analysis using a microscope.
It is important to always inform your doctor whenever you notice blood in your urine, regardless of how minor or infrequent the episode may seem. While many causes of hematuria are relatively benign, some underlying conditions can be serious and require prompt medical evaluation and treatment. Never assume that blood in the urine will simply resolve on its own without proper investigation.
A Quick Look at Urinary System Anatomy
Urine is a liquid waste product produced and eliminated by the body through the urinary system, whose primary function is to remove excess fluids and waste substances by dissolving them into urine for excretion. The urinary system is composed of the following main structures:
- Two kidneys
- Two ureters
- The bladder
- The urethra
The kidneys are two bean-shaped organs, each roughly the size of a closed fist. They are located just below the rib cage, one on each side of the spine. Every day, the kidneys filter approximately 120 to 150 liters of blood to produce about 1 to 2 liters of urine, which contains waste products and excess fluid removed from the bloodstream. It is worth noting that children naturally produce less urine than adults due to their smaller body size and lower fluid intake.
Urine flows from the kidneys down to the bladder through two narrow tubes called ureters. The bladder is a hollow, muscular organ that stores urine until it is ready to be released through the process of urination. When the bladder is sufficiently full, it signals the brain, and urine is expelled from the body through a tube called the urethra, located at the base of the bladder. In men, the urethra passes through the prostate gland before exiting the body, while in women it is considerably shorter and located separately from the reproductive organs.
Understanding this basic anatomy helps explain why blood in the urine can originate from many different locations along the urinary tract, from the kidneys themselves down to the bladder and urethra, and why identifying the exact source is such an important part of the diagnostic process.
Causes
There are numerous possible causes for the presence of blood in the urine, ranging from relatively minor and self-limiting conditions to more serious underlying diseases. Common and generally less concerning causes include:
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Infections of the bladder (cystitis), the kidney (pyelonephritis), or the prostate in men (prostatitis). These infections cause inflammation of the urinary tract lining, which can lead to bleeding.
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Trauma, such as a direct blow to the abdomen, back, or pelvic area, which can damage the kidneys, bladder, or urinary tract and cause visible or microscopic bleeding.
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Particularly intense physical exercise, especially activities involving prolonged running or repetitive impact, which can cause temporary and generally harmless bleeding, discussed in more detail in the dedicated section below.
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Viral illness, such as viral hepatitis, an infection that causes inflammation of the liver and, in some cases, can be associated with changes in kidney function and urine composition.
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Sexual activity, which can occasionally cause minor irritation or microtrauma to the urethra or bladder, resulting in small amounts of blood in the urine.
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Menstruation, which can sometimes lead to the presence of blood in a urine sample if contamination occurs during collection, rather than representing true hematuria originating from the urinary tract.
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Endometriosis, a condition exclusively affecting women, in which tissue similar to the lining of the uterus grows outside of it, sometimes on the bladder itself, occasionally causing cyclical blood in the urine that corresponds with the menstrual cycle.
More serious causes of hematuria, which require careful medical evaluation and prompt treatment, include:
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Bladder cancer or kidney cancer, both of which can cause painless blood in the urine, often as one of the earliest detectable warning signs.
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Blood clotting disorders, such as hemophilia, a genetic condition in which the blood does not clot properly, increasing the risk of spontaneous bleeding throughout the body, including within the urinary tract.
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Sickle cell anemia, an inherited genetic disorder in which the body produces abnormally shaped red blood cells that can obstruct small blood vessels, including those within the kidneys, leading to tissue damage and bleeding.
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Polycystic kidney disease, a genetic condition characterized by the development of numerous fluid-filled cysts within the kidneys, which can eventually impair kidney function and cause bleeding.
It is also worth remembering that certain medications and foods, including beets, rhubarb, and occasionally berries, can cause a change in urine color that closely resembles blood but is not actually related to bleeding. In most cases, this color change can be easily distinguished from true hematuria based on the pattern of discoloration and the absence of blood cells on laboratory testing, but it is always advisable to mention any recent dietary changes to your doctor if you notice unusual urine coloration.
Risk Factors
Certain individuals are at a higher risk of developing hematuria due to specific underlying conditions or lifestyle factors, including:
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Enlarged prostate (benign prostatic hyperplasia) in men, a common condition associated with aging that can cause irritation and bleeding within the urinary tract.
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The presence of kidney stones or urinary tract stones, which can scratch or irritate the lining of the urinary tract as they pass, causing both pain and bleeding.
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The use of certain medications, including anticoagulants (blood thinners), aspirin, other pain relievers (particularly nonsteroidal anti-inflammatory drugs), and certain antibiotics, all of which can increase the likelihood of bleeding within the urinary tract or cause direct irritation to the bladder lining.
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Participation in intense physical exercise, particularly high-impact activities such as long-distance running, which is discussed in greater detail in the following section.
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The presence of a bacterial or viral infection, such as streptococcal infection, which in rare cases can trigger an immune-related kidney inflammation known as post-streptococcal glomerulonephritis.
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A family history of kidney disease, which can increase an individual’s genetic predisposition to conditions such as polycystic kidney disease or other hereditary kidney disorders associated with hematuria.
It is important to note that in some cases, an apparent change in urine color may actually be related to menstrual bleeding rather than true blood originating from the urinary tract itself. Women should always mention their menstrual cycle status when providing a urine sample for testing, as this can help avoid unnecessary further investigation for a false positive result.
Blood in Urine in Runners
Although it can be quite alarming to notice, the temporary presence of blood in the urine following particularly intense physical exertion, such as long-distance running, is generally considered a benign and self-limiting phenomenon. This condition, sometimes referred to as exercise-induced or sports-related hematuria, has actually been recognized in medical literature for decades.
The exact underlying mechanisms are not yet fully understood, but among the most commonly suspected causes is repetitive mechanical trauma to the bladder wall, caused by the bladder repeatedly contracting against itself when relatively empty during prolonged periods of physical activity, leading to minor abrasion of the bladder lining.
In most cases of exercise-induced hematuria, no other accompanying symptoms are present, and the condition typically resolves on its own within a few days of rest, without requiring specific medical treatment.
The intensity and duration of physical activity, along with the athlete’s hydration status, are considered the most significant risk factors for developing this type of hematuria. Additionally, any falls, collisions, or direct trauma sustained during physical activity can further increase the likelihood of blood appearing in the urine.
It is also worth noting that in some cases, the discoloration observed in urine following intense exercise is not actually caused by blood at all, but rather by breakdown byproducts released from damaged muscle tissue, a condition known as myoglobinuria. This is particularly common following repeated eccentric muscle contractions, such as those experienced by the quadriceps muscles during prolonged downhill running, which can cause significant muscle microtrauma and the release of muscle proteins into the bloodstream and subsequently into the urine.
Despite the generally benign nature of exercise-induced hematuria, it is still advisable to mention any episodes to your doctor, particularly if the blood persists beyond a few days, is accompanied by pain, or occurs repeatedly, as this could indicate an underlying issue that warrants further evaluation.
Symptoms
Individuals with gross (macroscopic) hematuria, meaning visible blood in the urine, will typically notice that their urine appears pink, red, or brown, sometimes described as resembling the color of cola. It is worth emphasizing that even a very small amount of blood is sufficient to cause a noticeable and significant change in urine color, meaning that the visible severity of discoloration does not necessarily correlate with the seriousness of the underlying cause. In the majority of cases, individuals with gross hematuria do not experience any other accompanying signs or symptoms.
Some individuals with gross hematuria may also pass small blood clots in their urine, which can be associated with bladder pain or back pain, particularly if the clots temporarily obstruct the normal flow of urine.
The presence of additional symptoms is generally closely related to the specific underlying condition causing the hematuria. Some of the most common associated conditions and their characteristic symptoms include:
Urinary tract infections
These infections occur when bacteria enter the body through the urethra and begin to multiply within the bladder. Common symptoms associated with urinary tract infections include:
- a persistent and frequent urge to urinate,
- pain or burning sensation during urination,
- strong or unpleasant-smelling urine,
- fever, particularly if the infection has spread beyond the bladder.
Kidney infections
These occur when bacteria manage to travel upward through the urinary tract and reach the kidneys. The signs and symptoms of kidney infections are often similar to those of bladder infections, but they are more frequently associated with flank pain (pain in the side of the back, below the ribs) and fever, which can sometimes be accompanied by chills, nausea, and general malaise.
Kidney stones
When crystals form within the kidneys and/or elsewhere along the urinary tract, they can cause severe, sharp, and often excruciating pain, commonly described as one of the most intense forms of pain a person can experience. This pain, often referred to as renal colic, can be so severe that it prevents the patient from finding any comfortable position, whether lying down, sitting, or standing.
Benign prostatic hyperplasia
The prostate gland, located just below the bladder and surrounding the upper portion of the urethra in men, often begins to enlarge naturally starting around the age of 50 to 60. This enlargement can compress the urethra, disrupting the normal flow of urine. The primary signs and symptoms of an enlarged prostate include difficulty initiating urination despite feeling an urgent or persistent need to do so, a weak or interrupted urine stream, and the need to wake up multiple times during the night to urinate (a symptom known as nocturia). It is worth noting that infection of the prostate gland, known as prostatitis, can produce very similar signs and symptoms, making clinical evaluation important to distinguish between these two conditions.
Cancer
Unfortunately, in many cases involving bladder or kidney cancer, no early warning symptoms are present, and the appearance of blood in the urine may be one of the first, or even the only, noticeable sign of an already advanced underlying malignancy. This underscores the critical importance of promptly investigating any episode of hematuria, even when it occurs without pain or other accompanying symptoms, as early detection significantly improves treatment outcomes for urinary tract cancers.
When to Contact a Doctor
It is strongly recommended to always contact your doctor whenever you notice blood in your urine, regardless of the following circumstances:
- even if it occurred only once,
- even if there are no other accompanying symptoms,
- even if the amount of blood appears to be very small.
Blood in the urine should never be ignored or dismissed, even when it appears to resolve on its own, as it can sometimes be an early indicator of a more serious underlying condition that requires prompt diagnosis and treatment. If you experience blood in the urine accompanied by severe pain, fever, inability to urinate, or other concerning symptoms, you should seek medical attention promptly, potentially through emergency services if symptoms are severe.
Diagnosis
When a patient presents with hematuria, the doctor will typically recommend a series of diagnostic evaluations to determine the underlying cause. This diagnostic process generally includes:
- a detailed medical history,
- a thorough physical examination,
- urine analysis,
- additional specialized tests, as needed based on initial findings.
Medical History
Through a careful and detailed review of the patient’s medical history, the doctor gathers essential initial clues that help guide the diagnostic process toward the most likely underlying causes. During this conversation, the patient will typically be asked to provide information about:
- past and current medical conditions,
- current symptoms and any associated discomfort,
- use of medications, supplements, or recreational substances,
- family history of kidney or urinary tract disease,
- recent physical activity, trauma, or sexual activity,
- for women, information about menstrual cycle timing.
This information helps the physician narrow down the range of possible causes and determine which additional tests may be most appropriate.
Physical Examination
During the physical examination, the doctor will pay particular attention to the abdomen and back, assessing for any areas of tenderness, pain, or abnormal findings in the region of the bladder and kidneys. Depending on the patient’s gender and specific clinical presentation, additional specialized examinations may be performed.
In men, the urologist may perform a rectal examination to evaluate the prostate gland for any signs of enlargement, tenderness, or abnormal texture that could indicate infection, benign enlargement, or, in some cases, prostate cancer.
In women, a gynecologist may perform a pelvic examination to assess for any gynecological conditions that could be contributing to the presence of blood in the urine or causing symptoms that overlap with urinary tract issues.
Rectal Examination
To perform this examination, the urologist will ask the patient to lie down on the examination table and draw their knees up toward their chest. Using a lubricated, gloved finger, the doctor will gently insert a finger into the rectum to assess the condition of the prostate gland, checking for signs of inflammation, enlargement, irregular texture, or masses that could suggest an underlying prostate condition, including infection or cancer.
Pelvic Examination
A pelvic examination involves a visual and physical assessment of a woman’s pelvic organs, including the vagina, cervix, uterus, and ovaries. During this examination, the gynecologist will ask the patient to lie down on the examination table with her feet resting on specialized supports positioned at the corners of the table. This position allows the specialist to perform the necessary evaluations efficiently and with reasonable comfort for the patient, helping to identify any gynecological conditions, such as endometriosis, that could be contributing to the presence of blood in the urine.
Urine Analysis
Given the nature of this particular symptom, urine analysis (urinalysis) represents a key diagnostic test, providing essential additional information that can help identify the underlying cause of hematuria. This laboratory test can detect the presence of red blood cells, white blood cells (which may indicate infection), bacteria, protein, and crystals within the urine, all of which provide valuable diagnostic clues.
Before collecting a urine sample, the healthcare provider may ask a female patient about the date of her most recent menstrual period, as menstrual blood can sometimes contaminate a urine sample and lead to a falsely positive result for hematuria. Proper collection technique, including a clean-catch midstream sample, helps minimize the risk of such false positives.
Other Tests
Depending on the initial findings from the medical history, physical examination, and urinalysis, additional specialized tests may be recommended to further investigate the underlying cause of hematuria. These may include:
Blood tests
A blood test involves drawing a sample of blood, which is then sent to a specialized laboratory for detailed analysis. This test can, for example, detect elevated levels of creatinine, a waste product resulting from normal muscle breakdown that is typically filtered out by the kidneys. Elevated creatinine levels in the blood can indicate impaired kidney function or underlying kidney disease. Additional blood tests may be performed to search for markers of utoimmune diseaseurt-lifestyle), which can sometimes affect kidney function and cause hematuria. In men, a PSA (prostate-specific antigen) blood test may also be ordered, as this marker is useful in assessing prostate health and can help guide further evaluation for prostate cancer when clinically indicated.
Computed tomography (CT scan)
A CT scan uses a combination of X-ray technology and advanced computer processing to create detailed cross-sectional images of the urinary tract, with particular attention to the kidneys in cases of hematuria. The doctor may ask the patient to drink a special contrast solution before the scan, which helps improve the clarity and diagnostic accuracy of the resulting images. During the procedure, the patient lies on a table that slowly moves through a large, tunnel-shaped scanning device that captures the necessary images using X-ray technology. The procedure does not require anesthesia and is generally quick and painless. A CT scan can help doctors diagnose kidney stones, urinary tract obstructions, infections, cysts, tumors, and traumatic injuries affecting the urinary system.
Cystoscopy
Cystoscopy is a specialized procedure performed by a urologist, a physician who specializes in disorders of the urinary tract, to directly visualize the inside of the bladder and urethra. This is accomplished using a cystoscope, a thin, flexible, tube-like instrument equipped with a small camera and light source. Depending on the specific circumstances, the patient may be given local anesthetic gel, mild sedation, or pain-relieving medication prior to the procedure to minimize discomfort. Cystoscopy is particularly valuable for detecting bladder cancer, as it allows the urologist to directly visualize any abnormal growths, lesions, or areas of inflammation within the bladder lining.
Kidney biopsy
A kidney biopsy is a procedure that involves removing a small sample of kidney tissue for detailed laboratory examination. Prior to the procedure, the doctor will typically administer mild sedation in combination with a local anesthetic to minimize discomfort, although general anesthesia is used in certain cases. Following the biopsy, a pathologist, a physician who specializes in diagnosing diseases through the examination of tissue samples, will carefully examine the collected tissue under a microscope in a specialized laboratory to determine whether the hematuria is being caused by an underlying kidney disease, such as glomerulonephritis or other structural kidney abnormalities.
Magnetic resonance imaging (MRI)
MRI is a diagnostic imaging test that creates detailed images of internal organs and soft tissues without using X-ray radiation, instead relying on powerful magnets and radio waves. The procedure does not require anesthesia, although patients with claustrophobia or fear of enclosed spaces may be offered mild sedation to help them remain calm and still throughout the scan. An MRI may sometimes require the injection of a contrast dye to enhance the clarity of the resulting images. With most MRI machines, the patient lies on a table that slides into a tunnel-shaped scanning device, which may be open or closed at one end depending on the specific type of machine used. Some newer MRI machines offer a more open design, which can help reduce feelings of confinement for anxious patients. During the scan, it is essential for the patient to remain completely still while the technician captures the necessary images, as movement can blur the results. Patients should also be prepared for loud, rhythmic noises produced by the machine during the scanning process. MRI can be particularly useful for diagnosing problems affecting specific internal organs, such as the bladder or kidneys, and can provide detailed information about soft tissue structures that may not be as clearly visualized using other imaging techniques.
Treatment
The treatment approach for blood in the urine depends entirely on identifying and addressing the specific underlying cause responsible for the bleeding. In cases where no serious underlying condition is identified, such as hematuria resulting from intense physical exercise, specific treatment may not be necessary, and the condition often resolves on its own with rest and adequate hydration.
However, it is essential to emphasize that any episode of blood in the urine should ALWAYS be reported to a doctor, even if it appears to resolve spontaneously or seems relatively minor. Only a qualified healthcare professional can properly evaluate the situation, order appropriate diagnostic tests, and determine whether further treatment or monitoring is necessary.
When an underlying cause is identified, treatment will be tailored specifically to that condition. For example:
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Urinary tract or kidney infections are typically treated with a course of appropriate antibiotics, selected based on the specific bacteria identified and their sensitivity patterns.
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Kidney stones may require pain management, increased fluid intake to help pass smaller stones naturally, or in some cases, specialized procedures such as shock wave lithotripsy or surgical removal for larger stones.
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Benign prostatic hyperplasia may be managed with medications designed to relax the muscles of the prostate and bladder neck, or to shrink the size of the prostate gland, with surgical intervention reserved for more severe or treatment-resistant cases.
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Bladder or kidney cancer, if detected, will require a comprehensive treatment plan developed by an oncology team, which may include surgery, chemotherapy, radiation therapy, or a combination of these approaches, depending on the specific type and stage of cancer identified.
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Blood clotting disorders may require specialized management by a hematologist, potentially including medication adjustments or specific treatments targeted at the underlying clotting abnormality.
Regardless of the underlying cause, ongoing follow-up with your doctor is essential to ensure that the condition is properly resolved and to monitor for any recurrence of symptoms over time.
Frequently Asked Questions
Is blood in the urine always a sign of a serious problem?
Not necessarily. While some causes of hematuria, such as cancer or kidney disease, are serious, many cases are related to relatively benign and treatable conditions, such as urinary tract infections, kidney stones, or intense physical exercise. However, because serious causes cannot be ruled out without proper evaluation, it is essential to always consult a doctor whenever blood is noticed in the urine.
Can stress cause blood in the urine?
Stress itself does not directly cause hematuria. However, stress-related behaviors, such as dehydration due to inadequate fluid intake or increased susceptibility to urinary tract infections, could indirectly contribute to its occurrence in some cases.
Does blood in the urine always cause pain?
No. Many cases of hematuria, particularly those associated with bladder or kidney cancer, occur without any pain whatsoever. This is precisely why painless blood in the urine should never be ignored, as it may be one of the only early warning signs of a more serious underlying condition.
How is microscopic hematuria found if it cannot be seen?
Microscopic hematuria is typically discovered incidentally during a routine urinalysis performed for another reason, such as a general health checkup, or during the evaluation of unrelated symptoms. The urine sample is examined under a microscope in a laboratory, allowing technicians to detect red blood cells that are not visible to the naked eye.
Should I be worried if I only had blood in my urine one time?
Yes, you should still contact your doctor even after a single episode of visible blood in the urine. While an isolated episode is often related to a benign cause, only a proper medical evaluation can rule out more serious underlying conditions, particularly since some serious causes, such as early-stage cancer, may not cause recurring or persistent symptoms initially.
