Your kidneys make urine (pee) by filtering waste, toxins, and extra fluid from your blood. If you have kidney disease, you may see changes in your urine. Normal urine is usually a clear to yellow color without any cloudiness. If your urine looks or smells different from what’s typical for you, it’s important to talk to your healthcare provider right away.

In this article, we’ll talk about some of the common ways that rare kidney disease can affect your urine so you know what to look for.

1. Foamy Urine

Foamy urine can look like several layers of small- to medium-sized bubbles that stay in the toilet bowl after you’re done urinating. In some cases, the bubbles may remain in the toilet even after flushing. Having a few small bubbles that go away quickly after you pee usually isn’t cause for concern. However, foamy urine may be a sign of proteinuria (protein in the urine). When there’s excess protein in the urine, it can trap air bubbles, creating foam.

Proteinuria is a common symptom of many different types of rare kidney disease, including membranoproliferative glomerulonephritis (MPGN), complement 3 glomerulopathy (C3G), and Alport syndrome. Proteinuria can happen if kidney disease damages the glomeruli — small filtering structures in the kidney. Normally, glomeruli only allow excess fluid and waste to pass from the blood into the urine. If the glomeruli are damaged, proteins from the blood (such as albumin) can squeeze through and end up in the urine.

If there are very high levels of protein in the urine, it can be a sign of nephrotic syndrome — a condition where the kidneys leak excessive protein due to damage in the glomeruli. In addition to foamy urine, you may notice the following symptoms if you have nephrotic syndrome:

• Edema (swelling) in your lower legs and feet, hand, or face
• Decreased appetite
• Stomach pain
• A feeling of being ill

In people who haven’t been diagnosed with chronic kidney disease, foamy urine doesn’t always mean there’s protein in the urine. A small 2012 study found that about 22 percent of people who went to the doctor for foamy urine had significant protein levels. Additionally, 31.6 percent of a tested subgroup had either mild or significant proteinuria. It’s always a good idea to see a healthcare provider if you think your urine looks foamy.

2. Bloody Urine

Hematuria (blood in the urine) can make your pee look red, pink, or brown, depending on how much blood is present. In kidney disease, hematuria can happen because of damage to the glomeruli. When the glomeruli are damaged, they may allow red blood cells to leak into the urine.

It’s also possible to have microscopic hematuria, where blood is present but not visible to the naked eye. This can be detected only through a urinalysis (urine test).

Blood in the urine isn’t always a sign of kidney disease. Many different conditions can cause hematuria, including:

• Urinary tract infections (UTIs)
• Kidney infections
• Kidney stones
• Enlarged prostate
• Bladder cancer
• Certain medications, such as cyclophosphamide, penicillin, and blood thinners
• Vigorous exercise

If you notice blood in the urine, it’s always important to see your healthcare provider. Hematuria can be the first sign of rare kidney diseases, such as Alport syndrome, a genetic disorder that affects kidney function, hearing, and vision.

3. Changes in Urine Color

The color of your urine can be a clue to how your kidneys are functioning. When you’re well hydrated, your urine should look clear or pale yellow. Dark yellow urine usually means you’re not drinking enough water.

If your pee is pink, red, brown, or tea-colored, it could be a sign of kidney disease. Hematuria is a common cause of a change in urine color, as discussed above. Excess protein in the urine can also make urine look darker.

A change in the color of your urine that doesn’t get better when you’re well hydrated may indicate a kidney problem. Other potential causes of discolored urine include:

• Certain foods, including beets, carrots, fava beans, or food with strong food dyes
• Medications and vitamins, such as vitamin C, B vitamins, phenazopyridine (Pyridium, AZO), and chemotherapy drugs
• Liver problems — Conditions affecting the liver can cause dark or brownish urine due to a buildup of bilirubin, a pigment released when red blood cells break down.

If your urine color changes and doesn’t return to normal, especially if accompanied by other symptoms like pain or swelling, consult a healthcare provider.

4. Smelly Urine

Urine doesn’t usually have a strong odor, but an unusually foul, sweet, or chemical-like smell may be a sign of another problem.

A urinary tract infection — a bacterial infection of the kidneys or bladder — can cause pungent, foul-smelling urine. People with chronic kidney disease have an increased risk of developing UTIs. The increased risk of infections in people with kidney disease can be related to the disease itself or treatments. In people with C3G, there may not be enough complement proteins (immune system proteins) to fight off harmful bacteria. Treatments, such as immunosuppressants and dialysis, can also make it harder for the immune system to fight infection.

If you have a UTI, you may have other symptoms, such as:

• Frequent urination
• An urgent need to urinate
• Pain or burning while urinating
• Cloudy urine

Sweet-smelling urine can also be a sign of uncontrolled diabetes. Uncontrolled diabetes can lead to high blood glucose (blood sugar) levels, which may contribute to kidney damage over time. If some sugar leaks from the blood into the urine, it can make the urine smell sweet or like honey.

Some foods, such as asparagus and garlic, can temporarily change the odor of your urine. Other medical conditions that can cause smelly urine include:

• Liver failure — Can cause a musty or ammonialike odor due to toxin buildup
• Dehydration — Produces strong-smelling, concentrated urine from lack of fluids
• Metabolic disorders — May lead to a musty urine smell due to difficulty processing certain substances
• Bladder fistula (an abnormal connection between the bladder and the intestines) — Can make urine smell like feces (poop) due to bacterial contamination
• Certain medications and supplements, including sulfa-based antibiotics, medications for diabetes medications and rheumatoid arthritis, and some vitamins — May cause urine to smell like sulfur or rotten egg

5. Less Urine

You’ll make less urine if you have kidney failure, also known as end-stage kidney disease. In kidney failure, the kidneys can no longer filter waste and fluids effectively, leading to oliguria (a significant decrease in urine output). Kidney failure typically happens in later stages of kidney disease. If you develop kidney failure, you’ll need dialysis or a kidney transplant.

If you’re making less urine, you’ll notice that you’re going to the bathroom less often than usual or not at all. Other symptoms of kidney failure include:

• Itching
• Fatigue (extreme tiredness that doesn’t improve with rest)
• Difficulty concentrating
• Muscle cramps
• Decreased appetite
• Nausea and vomiting
• Insomnia (difficulty falling or staying asleep)

If you notice changes in how often you need to urinate, talk to your healthcare team right away. If you suddenly stop needing to urinate as often as usual, it could be a sign of acute kidney injury.

Seek Medical Care if You Notice Urine Changes

If you experience persistent changes in your urine, it’s important to contact your healthcare provider. If you haven’t been diagnosed with kidney disease, persistent urine changes could be an early sign that further testing is needed. If you’ve already been diagnosed with a rare kidney disease, urine changes can signal a change in your kidney function.

Urine and blood tests are often the first step to figuring out the cause of your urine symptoms. Depending on the findings, you may need additional testing. Based on the test results, your healthcare team can guide you to the best treatment option.

Talk With Others Who Understand

At MyKidneyDiseaseTeam, the site for people with kidney disease and their loved ones, people come together to gain a new understanding of different kidney diseases and share their stories with others who understand life with kidney disease.

Have you noticed any signs of kidney disease in your urine? Did treatment improve your symptoms? Comment below, start a new conversation on your Activities page, or connect with like-minded members in Groups.