Foamy urine: when to get it checked

Noticing foam or bubbles in the toilet can be worrying. Most of the time foamy urine is harmless. But urine that is foamy every time, and stays foamy, can sometimes be a sign that protein is leaking from the kidneys. A simple urine test can check.

Normal bubbles and harmless causes

Some bubbles are normal. They usually disappear within a minute or so. Common harmless reasons for foam include:

• A fast or forceful stream, especially after holding urine for a long time. Air mixes with the urine as it hits the water.
• Concentrated urine. When you have not drunk much, or have been sweating in the Mombasa heat, urine is darker and can foam more. First urine in the morning is often more concentrated.
• Toilet cleaning products left in the bowl, which can react with urine and make foam.
• Small amounts of semen in the urine after sex, in men.

If foam goes away when you drink more water, and does not happen every time, it is less likely to be caused by protein.

When foam may mean protein

Healthy kidney filters let waste through into the urine but keep useful proteins, such as albumin, in the blood. When the filters are damaged, protein can leak into the urine. Doctors call this proteinuria, or albuminuria when it refers to albumin specifically. Large amounts of protein can make urine look frothy, a bit like beaten egg white.

Foam is more likely to be worth checking when it:

• appears most or all of the time, for several days or weeks;
• stays in the toilet for several minutes;
• comes with swelling of the feet, ankles or around the eyes;
• happens in someone with diabetes, high blood pressure, a family history of kidney disease, or a known kidney condition.

It is important to know that small amounts of protein do not cause visible foam. Many people with early kidney damage have normal-looking urine. That is why people with diabetes or high blood pressure are advised to have regular urine tests even when they feel well. Read more about protein in urine.

How it is checked

Looking at urine cannot tell you whether it contains protein. Tests can. A clinician may use:

• A urine dipstick, a quick strip test done in a clinic or lab. It gives a rough idea of protein, blood and sugar. See urinalysis.
• A urine albumin-to-creatinine ratio (ACR), a more accurate lab test that measures albumin. KDIGO recommends ACR for detecting and following albuminuria. An early morning sample is preferred. See urine ACR test.
• A blood test for creatinine and eGFR, to estimate how well the kidneys are filtering.

Protein in the urine can rise for a short time because of fever, hard exercise, a urine infection, menstruation or very high blood sugar. So if a test is positive, it is usually repeated before any conclusion is drawn. Kidney damage is only described as chronic when the change is present for more than 3 months.

What the results may lead to

If there is no protein, and foam was only occasional, your clinician may simply reassure you. If protein is found and confirmed, the clinician will look at it together with your eGFR, blood pressure, blood sugar and history. This is how kidney health is assessed under the KDIGO 2024 guideline: eGFR and albuminuria are looked at together, over time. Some people will be monitored by their usual doctor. Others may be referred to a kidney specialist (nephrologist), for example if a lot of albumin is found.

When to see a doctor

Arrange to see a doctor or clinical officer if your urine is foamy most of the time for more than a week or two, or sooner if you also have swelling, or if you have diabetes, high blood pressure or a kidney condition. A urine test is quick, inexpensive and widely available in Mombasa.

Preparing for your appointment

It helps to note how long you have noticed the foam, how often it happens, and whether it goes away when you drink more. Mention any swelling, recent illness or fever, and bring a list of your medicines and any earlier urine or blood test results. If you are asked to give a sample, the first urine of the morning is often preferred for albumin testing. Ask the clinic how they would like it collected.

This page explains what a test or condition involves. It is not a diagnosis and does not replace advice from a doctor who knows your history. Your results should be interpreted together with your symptoms, other tests and a clinical assessment. Medical disclaimer.