- Journal List
- Clin J Am Soc Nephrol
- v.14(11); 2019 Nov 7
- PMC6832055
Clin J Am Soc Nephrol. 2019 Nov 7; 14(11): 1664–1666.
Published online 2019 Oct 1. doi:10.2215/CJN.06840619
PMCID: PMC6832055
PMID: 31575619
Is This a Sign of Kidney Disease?
Zeid J. Khitan
1 and Richard J. Glassock2
Author information Copyright and License information Disclaimer
Historically, persistent foamy urine noticed upon voiding is considered a warning sign of kidney disease. Foamy urine is characterized by the appearance and persistence of multiple layers of small to medium bubbles in urine voided into a container, such as a toilet bowl (see Figure 1). The appearance of a single layer of larger bubbles upon voiding, that quickly dissipate, can be considered normal. Traditionally, foamy urine has been considered by physicians, as well as by patients, as a marker of proteinuria. In fact, it is listed by most electronic health records in their customizable specialty templates as a symptom of kidney disease. Only about one third of patients volunteering this complaint will be found to have abnormal proteinuria, so most cases of “foamy” urine remain unexplained (1). We found no studies specifically examining the physio-chemical characteristics of urine that foams upon voiding.
Figure 1.
Foamy urine. (A) Freshly voided urine by a patient with nephrotic syndrome. (B) List of amphiphilic metabolites in normal human urine.
Recently, this topic was discussed in the American Society of Nephrology Communities website where many nephrologists shared their inputs and understandings (https://community.asn-online.org/home). It was clear that we are far from fully knowing exactly what foamy urine means. A better understanding of this phenomenon might be achieved by looking at mechanisms of foam formation in general and asking several questions:
How does foam form?
Besides protein, what substances in urine make foam appear?
Can foamy urine indicate something other than proteinuria?
Foam forms by trapping pockets of gas in liquid with the help of surfactant. A surfactant is an organic compound that is amphiphilic (or amphipathic), meaning containing both hydrophilic and hydrophobic ends. A surfactant diffuses in water and adsorb at interfaces between air and water where the water insoluble hydrophobic ends aggregate to form a bubble. The cleaning property of soap comes from its amphiphilic structure: when placed in an immiscible biphasic system consisting of aqueous (water) and organic solvents (fatty dirt), soap will partition the two phases, and the extent of the hydrophobic and hydrophilic portions determines the extent of partitioning. The foam in beer (“beer head”) is dependent on an amphipathic protein (Lipid Transport Protein 1) derived from barley (2).
In general, proteins or polypeptides have amphiphilic properties that can function as a surfactant and form foam in the urine. On the other hand, certain free amino acids share this property and potentially can also contribute to foam formation. The classic example of this is aminoaciduria that can be seen in Fanconi syndrome. Among such amino acids are methionine and tyrosine, both of which have strong amphiphilic properties, and patients with Fanconi syndrome can excrete significant amounts of these amino acids in the urine, exceeding 500 mg in 24 hours (3). Aminoaciduria is also common in several disorders with proximal tubular dysfunction as seen in Dent disease (4), Wilson disease (5), cadmium toxicity (6), and multiple myeloma, and has been described in individuals with SLC5A2 mutation encoding SGLT2 (7). It is only our prediction, without being extensively validated by observation, that individuals with such disorders have the potential to form foamy urine even though a dipstick will be negative for albuminuria. It remains to be seen if the wider use of the SGLT2 inhibitors is going to increase the incidence of foamy urine.
Phospholipids, a constituent of the lipid bilayers of cell membranes, are also amphiphilic. It is not unreasonable to expect that ruptured cells releasing membrane phospholipids in the urine, as in microscopic hematuria and/or pyuria without proteinuria, can contribute to formation of urine foam.
To address this topic more broadly, we searched the human metabolome database (HMDB) looking specifically for metabolites in human biospecimens with amphiphilic properties (8). Our search defined a total of 88 metabolites detected in human body secretions out of which, 16 were detected in human urine as shown in Figure 1. Fifteen of these metabolites are either primary or secondary bile salts and one is a fatty acid ester. The content of these metabolites in human urine could not be found. It is important to point out that these substances with amphiphilic properties are present in normal urine, which could explain the tendency of some individuals to form a single layer of foam upon voiding, especially if the urine is concentrated. It is expected that persons with cholestasis can have excess of most of these metabolites in their urine, contributing to foam formation. Moreover, laxatives that stimulate the flow of bile into the duodenum (cholagogue) or stimulate the production of bile by the liver (choleretic) can potentially increase bile salt excretion in the urine after escaping the enterohepatic circulation. Persons with enteric bacterial overgrowth potentially can have excessive amount of glycocholic acid and glycoursodeoxycholic acid, whereas those with carnitine palmitoyltransferase 2 deficiency and celiac disease can excrete excess L-palmitoylcarnitine in their urine. It is predicted that such conditions with relative excess in bile salts can potentially be the reason for urine foam formation in the absence of proteinuria.
As a subjective experience, foamy urine is a highly variable phenomenon, difficult to quantify and not referenced, but remains a free test and a spontaneous complaint that should not be ignored. Only about one third of patients volunteering this complaint will ultimately be found to have abnormal proteinuria, so most cases of foamy urine remain unexplained. The presence of abnormal (excessive) amounts of the normally present amphiphilic substances in the urine (as in cholestasis) as well as the possibility of other unidentified substances of similar chemical character originating from certain food items or medications may explain this discrepancy. Dipsticks can miss overflow free light chain proteinuria in monoclonal gammopathies, so if foamy urine of recent onset is a chief complaint, and the dipstick is negative or trace for albuminuria, we would recommend performing a urinary protein-to-creatinine ratio because a urinary albumin-to-creatinine ratio would be insufficient. Conditions that can have more than the usual bile salt concentrations in the urine might be other potential causes of this phenomenon. We encourage clinicians to stress foamy urine primarily with their patients who suffer from a relapsing glomerular disease or are members of families with certain genetic kidney disorders to facilitate early detection of disease relapse or early diagnosis, respectively, that can have a major impact on outcome. Better understanding of this phenomenon is expected when urinary metabolomic profiling becomes complementary to existing clinical and laboratory diagnostic modalities that will have the potential to uncover a variety of substances in the urine with amphiphilic properties. With the current understanding and the available knowledge, we do not recommend investigating foamy urine in patients who lack proteinuria. There is definitely much room for more research to better understand foamy urine.
Disclosures
Dr. Glassock reports consultant personal fees from Achillion, Apellis, Bristol-Myers Squibb, Chemocentryx, Ionis, Mallinckrodt, Omeros, and Retrophin; speakers bureau fees from Genentech; and editorial stipends from Karger and Wolters Kluwer during the conduct of the study. Dr. Khitan has nothing to disclose.
Acknowledgments
The authors wish to thank Dr. Hayder Aledan, Dr. Octavio Alvarez, Dr. Roger Rodby, Dr. J. Ganesh Bhat, Dr. Marwan Abu Minshar, Dr. Joshua D. King, and Dr. Ashraf El-Meanawy for the valuable discussion in ASN Communities Open Forum.
The content of this article does not reflect the views or opinions of the American Society of Nephrology (ASN) or CJASN. Responsibility for the information and views expressed therein lies entirely with the author(s).
Footnotes
Published online ahead of print. Publication date available at www.cjasn.org.
References
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Articles from Clinical Journal of the American Society of Nephrology : CJASN are provided here courtesy of American Society of Nephrology
FAQs
Is foamy urine always a sign of kidney disease? ›
Seeing foam in the toilet bowl on a regular basis may be a warning sign of kidney disease. Your kidneys might be leaking protein into the urine, which causes foamy-looking urine. It's important to let your doctor know how often you're seeing bubbly urine.
What causes your urine to be a little foamy? ›What Causes Foamy Urine. Foamy urine is a sign of protein in the urine, which is not normal. “Kidneys filter the protein, but should keep it in the body,” explains Dr. Ghossein. If kidneys are releasing protein into the urine, they are not working properly.
How much foam in urine is normal? ›"After you urinate, a single layer of larger bubbles that disappears within a couple of minutes is considered normal, but foamy urine is multiple layers of tiny to medium-sized bubbles in the toilet bowl that do not go away after a few minutes,” explains Ana Claudia Onuchic-Whitford, MD, a nephrologist at Brigham and ...
Is foamy urine always proteinuria? ›Foamy urine is widely regarded as a sign of proteinuria. However, there is no objective definition of foamy urine and there are no reports on the proportion of involved patients who have overt proteinuria or microalbuminuria.
What are the 3 early warning signs of kidney disease? ›- Changes in urination. Healthy kidneys help filter blood to create urine. ...
- Fatigue. ...
- Itching. ...
- Swelling in your hands, legs, or feet. ...
- Shortness of breath. ...
- Pain in the small of your back. ...
- Decreased appetite. ...
- Puffiness around your eyes.
Stage 1 CKD means you have a normal estimated glomerular filtration rate (eGFR) of 90 or greater, but there is protein in your urine (i.e., your pee). The presence of protein alone means you are in Stage 1 CKD.
Does foamy urine go away by itself? ›Bubbles that flush away are normal. If you have excess protein in the urine, the bubbles sometimes will persist after flushing. If many bubbles remain after flushing, this may be abnormal.
What color is urine when your kidneys are failing? ›When kidneys are failing, the increased concentration and accumulation of substances in urine lead to a darker color which may be brown, red or purple. The color change is due to abnormal protein or sugar, high levels of red and white blood cells, and high numbers of tube-shaped particles called cellular casts.
What does protein in urine look like? ›Proteinuria is high levels of protein in your pee. If you have proteinuria, you may have to pee more often, and your pee may be foamy or bubbly.
Can some medications cause foamy urine? ›Medications. Certain medications can also cause bubbles or foam in your urine. For example, some medications that treat urinary tract infections have been known to cause foamy urine.
Can anxiety cause foamy urine? ›
Foamy urine can occur if you have high protein levels in your urine, which could result from kidney disease. Other things — such as pregnancy, stress, or a urinary tract infection — may also cause foamy urine.
How do you know if you have CKD? ›- weight loss and poor appetite.
- swollen ankles, feet or hands – as a result of water retention (oedema)
- shortness of breath.
- tiredness.
- blood in your pee (urine)
- an increased need to pee – particularly at night.
- difficulty sleeping (insomnia)
- itchy skin.
A number of studies have demonstrated that CKD can develop in patients without albuminuria or proteinuria.
Does protein in urine always mean kidney disease? ›A small amount of protein in your urine is normal, but too much can be a sign of kidney disease.
What is the biggest indicator of kidney disease? ›Glomerular filtration rate is the best overall indicator of kidney function. It is superior to the serum creatinine level, which varies with age, sex, and race and often does not reflect kidney function accurately.
How do I check if my kidneys are OK? ›Blood Tests. Because your kidneys remove waste, toxins, and extra fluid from the blood, a doctor will also use a blood test to check your kidney function. The blood tests will show how well your kidneys are doing their job and how quickly the waste is being removed.
How do I know if my kidneys are okay? ›GFR is the best way to test how well the kidneys are working, so know your GFR number! A urine test to find out how much protein is in the urine. Healthy kidneys keep the body's protein levels just right. When protein is filtered out of the body or “spilled” into the urine, it is a sign of damage.
Why is my pee foamy but no protein? ›Phospholipids, a constituent of the lipid bilayers of cell membranes, are also amphiphilic. It is not unreasonable to expect that ruptured cells releasing membrane phospholipids in the urine, as in microscopic hematuria and/or pyuria without proteinuria, can contribute to formation of urine foam.
How long can you have kidney disease without knowing? ›Around 90 percent of people who have this condition are unaware they have it. 2 out of 5 adults who have CKD don't know they have severe chronic kidney disease. People with CKD can live for years without knowing, as it doesn't always have the most clearly defined symptoms.
What is mild kidney disease? ›Stage 1 of CKD
Stage 1 CKD means you have a normal eGFR of 90 or greater and mild damage to your kidneys. Your kidneys are still working well, so you may not have any symptoms. You may have other signs of kidney damage, such as protein in your urine.
How long does foamy pee stay foamy? ›
Bubbles in normal urine stay only for a few minutes. They tend to disappear once the toilet is flushed. If the bubbles are persistent even after flushing it is a sign of an underlying health condition.
How do doctors treat foamy urine? ›The treatment options for foamy urine depend on the underlying cause. If a person is dehydrated, they should drink more clear fluids until the urine is pale yellow or nearly transparent. If diabetes is the underlying cause, a doctor may prescribe oral medications or insulin injections to reduce blood sugar levels.
What foods reduce protein in urine? ›...
Diet For Proteinuria
- Oranges and orange juice.
- Leafy green vegetables, such as spinach and greens (collard and kale)
- Potatoes.
Underlying kidney problems
If the kidneys are damaged or infected, a person can experience abnormal urination, including clear urination. They may also have other symptoms, such as painful urination or a fever.
Urination changes (foamy; dark orange, brown, tea-colored or red if it contains blood; and urinating more or less than normal)
What color is urine when creatinine is high? ›Symptoms of the condition include: high blood pressure. blood in the urine, which may make it appear pink or brown. urine that appears foamy due to high levels of protein.
When should I be worried about protein in my urine? ›High levels of protein in your urine over a period of time may be the first sign that kidney disease or another condition has damaged the filters in your kidneys. A protein in urine test can help you find kidney damage early so you can make changes to protect your kidneys.
How can I test my urine for protein at home? ›To test your urine each day, use a simple test kit that contains a urine testing strip that you dip into a fresh sample of your urine. Follow the instructions on the kit. Find the results by matching the color of the strip to color blocks on the container.
How worried should I be about protein in my urine? ›Low levels of protein in urine are typical. Temporarily high levels of protein in urine aren't unusual either, particularly in younger people after exercise or during an illness. Persistently high levels of protein in urine may be a sign of kidney disease.
What kind of kidney disease causes foamy urine? ›Amyloidosis is a rare condition that can also cause foamy urine, fluid buildup, and problems for the kidneys. It is caused by the buildup of a specific protein, and can affect many organs.
Can a kidney disease be cured? ›
There's no cure for chronic kidney disease (CKD), but treatment can help relieve the symptoms and stop it getting worse. Your treatment will depend on the stage of your CKD. The main treatments are: lifestyle changes – to help you stay as healthy as possible.
Can blood pressure cause foamy urine? ›Any disease or problem that affects kidney function (like a as kidney infection, kidney failure, high blood pressure or kidney stones) can cause foamy urine.
Can High BP cause foamy urine? ›You have excess protein in your pee due to kidney problems. Consistently high levels of protein in your urine are a sign that something is allowing your kidneys to leak more protein into your pee than they should. Diabetes and high blood pressure are two major causes of this, Dr. Ramin says.
Does foamy urine mean diabetes? ›Long-standing diabetes causes diabetes-related nephropathy. Symptoms don't appear until later stages, but they include swelling, peeing more often, foamy pee, nausea and fatigue.
What does it feel like when something is wrong with your kidneys? ›A severe decrease in kidney function can lead to a buildup of toxins and impurities in the blood. This can cause people to feel tired, weak and can make it hard to concentrate. Another complication of kidney disease is anemia, which can cause weakness and fatigue. You're having trouble sleeping.
How do you rule out kidney disease? ›The main test for kidney disease is a blood test. The test measures the levels of a waste product called creatinine in your blood. Your doctor uses your blood test results, plus your age, size, gender and ethnic group to calculate how many millilitres of waste your kidneys should be able to filter in a minute.
What are 3 diseases that affect the kidney? ›- Polycystic Kidney Disease (PKD)
- Simple Kidney Cysts.
- Kidney Infection (Pyelonephritis)
- Kidney Stones.
Itching with kidney disease can be generalized, or it can occur in specific parts of the body. Common areas for this type of itching include the head, arms, back, and abdomen. It also tends to be worse at night, which can disturb your sleep.
How fast does kidney disease progress? ›Kidney disease progresses at different rates for different people, and it can take between two and five years to pass between different stages. Kidney disease stages are measured by using a blood test to check the estimated glomerular filtration rate (eGFR).
Can early kidney disease be stopped? ›While it's not possible to reverse kidney damage, you can take steps to slow it down. Taking prescribed medicine, being physically active, and eating well will help. You'll also feel better and improve your overall well-being.
What is the difference between bubbles and foam in urine? ›
“Bubbles are bigger, clear and flushable,” Dr. Ghossein explains, noting that everyone will have bubbles in the toilet after urinating. Foam, on the other hand, is white, and it stays in the toilet after you flush.
Can protein in urine be temporary? ›Transient proteinuria — Transient (intermittent) proteinuria is by far the most common form of proteinuria. Transient proteinuria usually resolves without treatment. Stresses such as fever and heavy exercise may cause transient proteinuria.
Can protein in urine resolve itself? ›What Treatment Follows Protein in the Urine? Protein from an infection or fever will most likely resolve on its own. If your doctor confirms that you have kidney disease, a treatment plan will be put together.
Does kidney disease always cause protein in urine? ›If there is a problem with your kidneys, protein can leak into your urine. High levels of protein in your urine over a period of time may be the first sign that kidney disease or another condition has damaged the filters in your kidneys.
Is proteinuria always a sign of kidney disease? ›Occasionally, proteinuria is an early sign of chronic kidney disease (CKD), although you can have CKD and have normal levels of protein in your urine. CKD is a gradual loss of your kidney functions, which may eventually require a kidney replacement therapy, dialysis or kidney transplant.
Is it bad to pee foamy? ›Passing foamy urine now and then is normal, for the speed of urination and other factors can influence this. But you should see your doctor if you have persistently foamy urine that becomes more noticeable over time. This can be a sign of protein in your urine (proteinuria), which requires further evaluation.
What to do when urine is foamy? ›The treatment options for foamy urine depend on the underlying cause. If a person is dehydrated, they should drink more clear fluids until the urine is pale yellow or nearly transparent. If diabetes is the underlying cause, a doctor may prescribe oral medications or insulin injections to reduce blood sugar levels.
Can proteinuria be harmless? ›Sometimes, almost always in children, proteinuria can be detected later in the day, but not in the morning. This is known as orthostatic Proteinuria and it is usually harmless.
Can proteinuria be temporary? ›There are three types of proteinuria: transient (temporary), orthostatic (related to sitting/standing or lying down), and persistent (always present). Certain types of urine testing are needed to determine the type of proteinuria.
Is clear urine a sign of kidney failure? ›Underlying kidney problems
If the kidneys are damaged or infected, a person can experience abnormal urination, including clear urination. They may also have other symptoms, such as painful urination or a fever.