Seeing blood in your urine can feel alarming. Sometimes it is easy to see, and sometimes it is found only during a urine test. Either way, hematuria is the medical term for blood in the urine. It is a sign, not a diagnosis by itself, and it deserves medical evaluation, as also emphasized by sources such as the Mayo Clinic.
Blood in the urine can come from different parts of the urinary tract, including the kidneys, ureters, bladder, prostate, or urethra. Some causes are relatively common and treatable, such as a urinary tract infection or kidney stones. Other causes may involve the kidneys’ filtering system and can require evaluation by a nephrologist. In some cases, hematuria can also be linked to a more serious urologic condition.
What Hematuria Means
Hematuria is blood in the urine.
There are two main types:
- Gross hematuria means the blood is visible.
- Microscopic hematuria means the blood is not visible to the naked eye and is usually found on routine testing or urine microscopy.
A urine dipstick may suggest that blood is present, but confirmation often requires microscopic examination of the urine, a standard approach described in publications such as American Family Physician.
It is also important to know that not all red or brown urine is caused by blood. Certain foods, pigments, and medications can change urine color. That is one reason testing matters.
Urine color can sometimes offer clues, but it cannot identify the source on its own. Bright red or pink urine may be more often associated with bleeding from a lower part of the urinary tract, while tea-colored or cola-colored urine may be more suggestive of a glomerular, or kidney-filter, source. Still, color alone cannot confirm whether the cause is nephrologic or urologic.
Can Kidney Disease Cause Blood in Urine?
Yes. Kidney disease can cause hematuria when the kidneys’ filtering structures are damaged.
Glomeruli are tiny filtering units inside the kidneys. Their job is to keep blood cells and important proteins in the bloodstream while allowing waste and extra fluid to pass into the urine.
The glomerular filtration barrier is the structure that helps the glomeruli stay selective. When inflammation, immune injury, or scarring disrupts this barrier, red blood cells and proteins such as albumin can pass from the blood into the urine.
That is why hematuria together with albuminuria or proteinuria is more concerning than hematuria alone. This combination may suggest structural injury to the kidney’s filtering system and may increase the need for nephrology evaluation.
In some cases, microscopic findings such as dysmorphic red blood cells or red blood cell casts can also suggest a glomerular source.
Why Blood Pressure, Creatinine, and eGFR Matter
Hematuria of kidney origin may occur along with high blood pressure, and that matters for two reasons. High blood pressure can be a clue that kidney disease is more significant, and it can also accelerate further kidney damage over time.
Your clinician may also look at serum creatinine and estimated glomerular filtration rate (eGFR). These are common markers used to assess kidney function. If hematuria appears together with albuminuria, reduced eGFR, rising creatinine, or high blood pressure, the level of concern is higher than with an isolated episode.
A single episode of hematuria does not always carry the same meaning as repeated or persistent hematuria. Persistence over time usually deserves closer follow-up.
Common Causes of Blood in Urine
Urinary Tract Infections (UTIs)
A urinary tract infection can irritate and inflame the lining of the urinary tract. That inflammation may lead to blood in the urine, often along with burning during urination, urinary urgency, urinary frequency, or lower abdominal discomfort.
Kidney Stones
Kidney stones are hard deposits made of minerals and salts. As they move through the urinary tract, they can cause pain, irritation, obstruction, and bleeding. Hematuria is a common symptom, especially when it occurs with severe pain in the side, back, lower abdomen, or groin.
Trauma or Injury
A blow to the back, abdomen, or pelvic area can cause blood in the urine. If hematuria appears after trauma, prompt medical evaluation is important because internal injury may be present even when it is not obvious from the outside.
Enlarged Prostate
In men, benign prostatic hyperplasia (BPH) can affect urine flow and may be associated with hematuria. It may also cause a weak stream, trouble starting urination, or the feeling that the bladder is not emptying completely.
Medicines
Some medicines, including blood thinners, are associated with hematuria. However, blood in the urine should not automatically be blamed on medication alone. Anticoagulants can make bleeding more noticeable, but they do not necessarily explain the underlying cause.
Evaluation is still important, as highlighted by organizations such as the Urology Care Foundation, which emphasize that hematuria should not be attributed to medication alone without proper assessment.
Vigorous Exercise
Strenuous exercise can sometimes cause temporary hematuria. Even so, visible blood in the urine or recurrent episodes should still be discussed with a healthcare professional so more serious causes are not missed.
Kidney-Related Conditions Associated With Hematuria
Glomerulonephritis
Glomerulonephritis is a group of diseases that inflame and damage the glomeruli.
This damage disrupts the glomerular filtration barrier. As a result, red blood cells and proteins can leak from the bloodstream into the urine.
People with glomerulonephritis may also have swelling, high blood pressure, albuminuria, or reduced kidney function. Because some forms can progress to chronic kidney disease, evaluation should not be delayed.
IgA Nephropathy
IgA nephropathy is a kidney disease in which immune deposits build up in the glomeruli and trigger inflammation.
This can cause the kidneys to leak blood and protein into the urine.
Treatment depends on how active the disease is, how much protein is in the urine, how well the kidneys are working, and whether blood pressure is controlled. Supportive care is often central, and some people may need additional therapy under nephrology supervision.
Polycystic Kidney Disease
Polycystic kidney disease (PKD) is an inherited disorder in which multiple cysts grow in the kidneys.
Hematuria can occur if a cyst bleeds or if kidney tissue becomes irritated or damaged. Ongoing follow-up is important because PKD can affect kidney function over time, as also noted by organizations such as the PKD Foundation.
Other Inherited or Immune Conditions
Other inherited and immune-mediated kidney disorders can also cause hematuria. In these cases, blood in the urine may be one clue that the kidneys are involved, but further testing is usually needed to identify the exact diagnosis.
Why Albuminuria Changes the Picture
Albuminuria is the presence of albumin, a type of protein, in the urine.
When hematuria appears together with albuminuria or proteinuria, clinicians become more concerned about possible damage to the kidney’s filtering system.
That is why your clinician may order a urine albumin-to-creatinine ratio (ACR), along with blood tests and other urine studies. Organizations such as KDIGO and the National Kidney Foundation emphasize the importance of evaluating both urine protein and kidney function when kidney disease is suspected.
When a Kidney Biopsy May Be Needed
A kidney biopsy is a procedure in which a small sample of kidney tissue is examined under a microscope.
It can help identify inflammation, scarring, immune deposits, and other structural problems.
Not everyone with hematuria needs a biopsy. However, a biopsy may be considered in selected cases, especially when hematuria is persistent, when there is significant proteinuria, or when kidney function is abnormal and blood and urine tests do not fully explain why.
More Serious Causes of Hematuria
Hematuria can sometimes be a warning sign of bladder cancer, kidney cancer, or another significant urinary tract problem. The risk of a malignant cause is often more concerning in older adults or in people with certain clinical risk factors. That is one reason blood in the urine should never be ignored, especially when it happens more than once.
Important Safety Advice
If you notice hematuria, do not assume the cause is minor and do not build your own treatment plan without medical guidance.
Be careful with over-the-counter NSAIDs, such as ibuprofen or naproxen. These medicines can worsen kidney function in some situations, especially if you are dehydrated, have low blood pressure, or have underlying kidney disease.
Diet changes also need to be handled carefully. Restrictions involving potassium, sodium, or protein should not be started “just in case.” The right diet depends on the diagnosis, kidney function, blood pressure, and lab results. Making major changes without guidance can be unhelpful or even harmful.
When Should You Seek Medical Attention?
Any visible blood in the urine should be discussed with a healthcare professional. Microscopic hematuria found on testing also deserves follow-up, especially if it is persistent.
Seek urgent medical care right away if hematuria occurs with:
- severe pain
- fever
- difficulty urinating
- blood clots
- weakness or lightheadedness
- a recent significant injury
These symptoms may indicate a more urgent problem that needs immediate attention.
Final Thoughts
Hematuria is a sign, not a diagnosis. The next step is proper evaluation to determine whether the source is urologic, nephrologic, temporary, or more serious.
Some causes of hematuria are transient. Others require closer monitoring or treatment. The key is not to assume the cause on your own. When hematuria appears together with albuminuria, high blood pressure, abnormal creatinine, or reduced eGFR, careful kidney evaluation becomes even more important.
FAQs
Is blood in urine always serious?
Not always. Some causes of hematuria are temporary or treatable, such as exercise, infection, or kidney stones. However, blood in the urine should never be ignored because it can also be linked to kidney disease, structural urinary tract problems, or cancer.
Can kidney disease cause blood in urine?
Yes. Kidney disease can cause hematuria when the glomeruli, which are the kidneys’ tiny filters, become inflamed or damaged. When the filtration barrier is disrupted, red blood cells and sometimes protein can leak into the urine.
What tests are used to evaluate hematuria?
Evaluation may include a urine dipstick, urine microscopy, urine albumin or protein testing, serum creatinine, eGFR, imaging, and sometimes cystoscopy or kidney biopsy. The exact workup depends on whether the source appears more urologic or nephrologic.
When should I seek urgent care for hematuria?
You should seek urgent care if blood in the urine happens with severe pain, fever, blood clots, difficulty urinating, weakness, or after a significant injury. These symptoms may point to a more urgent problem that should be assessed quickly.