If you have a rare kidney disease, seeing blood in your urine — called hematuria — can be alarming. Even if you’re unsure whether it’s linked to your condition, it’s natural to feel worried.

If you’re concerned, knowing a few key facts can help you talk with your doctor more confidently. Together, you can determine the cause, explore treatment options, and work toward improving your overall well-being.

What Can Cause Blood in the Urine?

Several causes can lead to blood in your urine, whether or not you have been diagnosed with a kidney disease. For instance, it can be caused by:

• Infections or inflammation of the urinary tract, kidney, or prostate
• Recent urinary tract or kidney procedures
• Any sort of trauma or kidney injury
• Intense exercise
• Medicines that help prevent blood clots and some anticancer medicines
• Endometriosis (a condition in which tissue similar to the lining of the uterus grows outside the uterine cavity)
• Sexual activity
• Enlarged prostate
• Kidney or urinary tract stones

There are a few more serious causes of blood in your urine, which can also occur alongside or independently of a rare kidney disease. These include:

• Urinary tract, kidney, or prostate cancer
• Sickle cell disease
• Disorders that affect how your blood clots

Causes of Blood in Urine Related to Kidney Diseases

Blood in the urine is seen in kidney diseases with glomerulonephritis, a condition that affects the glomeruli (filters of the kidneys). This includes some forms of rare kidney disease.

If this blood in your urine is something you need to watch out for, your nephrologist (kidney specialist) should tell you so that it will not be such a shock when you see it for the first time. Note that not all rare kidney diseases cause blood in the urine, so you’ll need to talk to your doctor to know what to expect.

In glomerulonephritis, the glomeruli are inflamed and damaged. Often, this is because your immune system is not working properly. This causes protein and blood to end up in your urine. Blood in the urine is one of the most common symptoms of glomerulonephritis.

Glomerulonephritis can be:

• Acute — Occurring suddenly, but treatable
• Chronic — Occurring slowly over years, sometimes leading to kidney failure
• Rapidly progressive — Occurring within a very short period (days or weeks)

Although the data on how many people with glomerulonephritis have hematuria is limited, a few studies show that it can occur in 64 percent to 76 percent of cases. Most of these people will have microscopic hematuria (such a small amount of blood in their urine that they can’t see it), which is detectable by a urine test. A smaller number of people will have what’s called gross hematuria (visible blood in their urine — “gross” in this case means “a larger amount”). When this happens, the urine may appear pink, red, or brown.

Acute glomerulonephritis can occur after certain bacterial and viral infections. There are other kidney diseases where glomerular inflammation and damage leads to blood in the urine.

Alport Syndrome

Alport syndrome is a genetic disease that involves your kidneys, as well as your ears and your eyes. Most people living with Alport syndrome will have blood in their urine because their kidneys aren’t working properly.

Alport syndrome is caused by changes in genes that produce a specific type of protein called collagen. Collagen helps form and strengthen connective tissues in your body, like skin, muscles, tendons, and ligaments. The specific type of collagen affected by Alport syndrome plays an important role in the glomeruli, which help remove unwanted substances from your blood and get rid of them in urine. When your kidneys have abnormal collagen, the glomeruli get damaged, and this results in blood in your urine. You’ll see that damage to the glomeruli is a common cause of blood in the urine.

Lupus Nephritis

Lupus nephritis often occurs in people who have been diagnosed with systemic lupus erythematosus, an autoimmune disease which is sometimes just called lupus. In lupus nephritis, your immune system attacks your kidneys, which leads to swelling, irritation, and inflammation. These attacks can leave your kidneys damaged, leading to the blood you see in your urine.

Membranoproliferative Glomerulonephritis

Membranoproliferative glomerulonephritis (MPGN) is a chronic kidney disease that damages the glomeruli. This damage often happens because parts of the immune system — like the complement system immunoglobulins (antibodies) — don’t work properly. Sometimes, antibodies stick together to form clumps called immune complexes, which can get stuck in the glomeruli and cause further damage. This is known as immune complex-mediated MPGN (IC-MPGN) and is more common than the type of MPGN linked mainly to a protein called C3 (known as C3 glomerulopathy). In most cases, IC-MPGN is triggered by the body’s own antibodies or by infections.

Complement 3 glomerulopathy (C3G) is a specific type of MPGN that is often linked to genetic factors. It happens when the immune system’s C3 protein becomes overactive and starts to build up in the glomeruli. This buildup causes inflammation and damages the filters. While genes are usually the main cause, sometimes autoantibodies can also trigger this process. Like other forms of MPGN, the damage can make the glomeruli leak blood into your urine, which is why you might see blood when you pee.

Children with MPGN are more likely than adults to have blood in their urine when they are first diagnosed.

Immunoglobulin A Nephropathy

Immunoglobulin A (IgA) nephropathy is another autoimmune disease that can affect your kidneys. In IgA nephropathy, clumps or globs of antibodies, particularly IgA antibodies, end up deposited in your kidneys. Your body isn’t able to process these antibodies, so over time they damage your glomeruli. As noted above, damaged glomeruli leak blood and protein into the urine, which explains the blood you’re seeing.

Goodpasture Syndrome

Goodpasture syndrome is another autoimmune disease that can cause you to have blood in your urine. In Goodpasture syndrome, your immune system attacks a structure called the basement membrane in your lungs and your kidneys by mistake. Most people with Goodpasture syndrome experience symptoms that have to do with their lungs first, like struggling to breathe, turning pale, or being more fatigued than normal. Eventually, as in other autoimmune diseases, continued attacks on the kidneys can damage the glomeruli, causing blood in your urine.

Polycystic Kidney Disease

Polycystic kidney disease (PKD) is a genetic condition where your kidneys grow sacs with fluid around them, called cysts. If you have quite a few cysts or they’re large, it can damage your kidneys or change the way they function. In at least one type of PKD, about half of the people diagnosed will see blood in their urine at some time. People with PKD are likely to see blood when a cyst bursts or when one of the small blood vessels around a cyst gets damaged. This blood can end up in the urine. They may also get kidney stones or kidney/urinary tract infections, which can also cause bleeding.

Talk to Your Doctor if You See Blood in Your Urine

If you’ve been diagnosed with a rare kidney disease and you see blood in your urine, it’s important that you talk to your nephrology team right away. If you haven’t had this symptom before, they’ll want to run some tests to figure out what’s causing it. If the cause isn’t related to your kidney disease, they’ll want to help you get the treatment you need right away. If it is related to your kidney disease, it may indicate that your disease is progressing or that your current medications aren’t working.

In fact, your healthcare provider may want to monitor your urine for blood on a regular basis. This may be able to help them determine what is going on with your kidneys at any given time and help track your overall kidney health. You may need to give regular urine samples and have them tested for traces of blood, even if you aren’t seeing anything. Keeping these checkup appointments can help you get the medical advice you need and stay on top of your rare kidney disease so you can feel your best.

Diagnosing Rare Kidney Diseases

If you haven’t been diagnosed with a rare kidney disease but your doctor suspects one, they’ll run a series of tests on you. The specific tests will depend on which kidney disease or diseases they suspect. However, you’re likely to experience one or more of the following tests.

Diagnosis is likely to start with blood tests and urine tests.

Genetic testing is common, since many of these diseases are passed down through the genes. Your doctors will look for specific genes that are known to be tied to specific kidney diseases.

You’re also likely to have one or more scans to help your doctors see your kidneys. These may be ultrasounds, computed tomography (CT) scans, or MRIs. The scan you get will depend on what your doctor needs to see to make a diagnosis.

Your doctor may also choose to biopsy your kidney or a specific part of it. This involves taking a small sample with a needle and looking at it in a lab. A kidney biopsy can help doctors understand what is going on in your body.

Together, these tests can help you get the rare kidney diagnosis you need. Then, you can put together a treatment plan so you can feel better.

Talk With Others Who Understand

MyKidneyDiseaseTeam is the social network for people with kidney disease and their loved ones. On MyKidneyDiseaseTeam, members come together to ask questions, give advice, and share their stories with others who understand life with kidney disease.

Have you experienced blood in your urine? Was it connected to a kidney disease or caused by something else? Share your experience in the comments below, or start a conversation by posting on your Activities page.