Protein in urine: what does this indicate?

Proteinuria is a symptom of an underlying health problem in which there are increased levels of protein in the urine. If it is left undetected or untreated, proteinuria can progress to more serious complications.

We spoke to Professor Liz Lightstone, one of our top consultant nephrologists operating in London, about this symptom to understand what it means to have it and what underlying health conditions might be causing it.

What is proteinuria?

Proteinuria is when there are increased levels of protein in the urine. Protein is essential to your body to help build and repair muscles and bones, regulate fluid, and fight infections. It is present in your blood and should remain there, but when protein is found in your urine, it means that too much is leaving your body.

Healthy kidneys filter blood, waste products, and excess water out of your body. Sometimes, however, small amounts of proteins can filter through, but when the kidneys aren’t filtering properly it can allow large amounts to pass through which isn’t healthy and usually indicates that you have a kidney problem.

What are the symptoms of proteinuria?

Most of the time, proteinuria has no symptoms as most people have low levels of protein in the urine. In these cases, it’s only detected during a routine screening for something else; for example, we always dip the urine of pregnant women, so it would be detected on this test.

If protein loss is heavy, however, the urine can have a foamy or frothy appearance. If it is really heavy, it can affect the way you hold fluid in your tissues, resulting in oedema which is associated with a puffy face and eyes and swollen ankles.

Does this mean I have an underlying condition that’s causing proteinuria?

Normally, yes. It is abnormal to have protein in your urine; so if tests reveal this is the case, it would make us look for a problem in your kidneys.

There can be a wide range of problems which make your kidneys leak protein, such as kidney stones, a disease of the glomeruli (the kidney’s filtering units) or chronic kidney disease to name a few. Other conditions can affect the function of your kidneys, leading to proteinuria such as diabetes and high blood pressure.

How is proteinuria tested?

To diagnose proteinuria, the initial step is to carry out a urine dipstick test to measure the quantity of protein in the urine. After you provide a urine sample, a dipstick made with a colour-sensitive pad is used to identify the level of protein in your urine. Sometimes, we may need to know which type of protein is in your urine, which would involve a further test.

You will need to see someone who can work through the diagnostic pathway. As there can be many causes of proteinuria, you may need to take a kidney biopsy to make a specific diagnosis.

What are the risk factors for proteinuria?

The most common risk factor of proteinuria is diabetes, which can affect how well the kidneys function. Proteinuria in diabetes will usually be the result of having long-term high blood sugar levels or hypertension. If there is a progressive rise in protein levels in the urine, it can lead to kidney damage - so your diabetes needs to be controlled.

How is it treated?

Treatment for proteinuria depends on what is causing it. If you have diabetes or high blood pressure, it is very important to make sure these are under control by following the treatment and advice given to you by your doctor. There are effective new treatments emerging to help people with diabetes to protect your kidneys. If there are other causes, such as kidney disease, then certain medications and a diet plan should be given.

As there are several causes of proteinuria, it is critical to get a correct diagnosis of the underlying condition to be able to offer the most effective treatment and prevent any kidney damage.

If you are worried you might have proteinuria, visit Professor Liz Lightstone’s Top Doctors profile and book a consultation to see her.