Has your doctor told you that you have protein in your urine? This condition — called proteinuria or albuminuria — can be an early sign that your kidneys aren’t working as well as they should. Proteinuria is common in people with IgA nephropathy (IgAN), and it’s one of the key markers your care team uses to understand how your kidneys are functioning.

Here’s what you need to know so you can understand your diagnosis and have informed conversations with your nephrology team. That way, you can get the best possible treatment for your kidneys.

What’s Proteinuria?

When your kidneys are working well, they filter a lot out of your blood, including some proteins. They keep needed proteins and other helpful substances in your blood while moving unwanted waste into your urine.

But if your glomeruli (the tiny filters in your kidneys) become damaged or irritated, they can start to leak. When that happens, protein can slip into your urine instead of staying in your bloodstream. This is called proteinuria.

In IgA nephropathy, your kidneys become damaged by a protein from your immune system called immunoglobulin A (IgA). Most of the time, IgA works with the rest of your immune system to fight off infections. However, in IgAN, this protein instead builds up in the glomeruli.

The glomeruli are very small blood vessels in your kidneys. They hold on to important substances, such as proteins, and send waste out through your urine. However, when IgA builds up in them, they become inflamed. Over time, as the glomeruli are damaged, they may become leaky and sometimes scarred as well. All of this makes it harder for them to filter well and may allow proteins like one called albumin to leak into your urine.

Proteinuria is associated with kidney disease that is progressing (getting worse). This means that if the underlying cause isn’t treated, your kidneys may lose function over time, and you may eventually develop kidney failure.

Proteinuria Causes

A number of factors can cause proteinuria. Short-term proteinuria can happen when you’re exposed to extreme cold, have a fever, get dehydrated, or do very strenuous exercise.

In the long term, proteinuria is connected to a number of other medical conditions, including chronic kidney diseases like IgAN, diabetic kidney disease, and hypertension. If a test shows protein in your urine, your doctor should work with you to figure out what’s causing it. In some cases, they may test you for other conditions even if you already know that you’re living with IgAN.

Some conditions that can lead to proteinuria but may not seem directly related to the kidneys include:

• Lupus
• Preeclampsia
• Multiple myeloma
• Heart disease and heart failure
• Malaria
• Rheumatoid arthritis
• Amyloidosis
• Hodgkin lymphoma

If you’re diagnosed with any of these conditions in addition to IgAN, talk to your healthcare provider about the possibility of proteinuria and what might be contributing to it. They can help you figure out what you can do to help reduce the protein in your urine and help support your kidney function.

Proteinuria and Your Immune System

Doctors and scientists don’t fully understand what causes IgA to begin to build up in your kidneys. However, some people start to have symptoms after they have an infection, like a cold, a respiratory infection, or a stomach infection (gastroenteritis). There’s no evidence that particular infections lead to IgAN. Instead, for some people, their immune system becomes activated while fighting an infection, especially one affecting the nose, throat, or gut. When this happens, the body may produce IgA that isn’t formed correctly. These IgA proteins can then build up in the glomeruli and cause inflammation.

If you’re living with IgAN, you may not notice many symptoms unless you have or have recently fought off an infection. This is called an IgAN flare, and you and your doctor will need to work to support your kidneys and help your immune system calm down.

Proteinuria and Your Genetics

There are also genes that seem to influence who does and doesn’t develop IgA nephropathy. In fact, at least 18 segments of different genes seem to be associated with the condition. Many of these have to do with how IgA is formed in the body. It’s possible that certain structures of IgA or methods of forming it are more likely to lead to IgAN.

That said, less than 10 percent of IgAN cases are strictly hereditary. Thus, IgAN seems to develop based on a combination of environmental and genetic factors. Researchers are trying to understand how these factors work together to cause IgAN in some people. If you know that you have a family history of IgAN, you should talk to your doctor about that. Other people in your family may need to be tested for it even if they aren’t showing symptoms.

Proteinuria and Blood Pressure

Most of the time, people assume that your blood pressure is connected to issues with your cardiovascular system, including various cardiovascular diseases. While this is true, it can also affect your kidneys in significant ways.

Earlier, this article discussed the tiny blood vessels in your kidneys that help with filtration. When you have hypertension (high blood pressure), the pressure in blood vessels in your kidneys also goes up. If your blood pressure stays high over a longer period of time, it can cause inflammation and kidney damage. This may mean that you end up with even more protein in your urine.

If you have high blood pressure alongside IgAN, your glomeruli may have problems for both of those reasons. You and your doctor will want to treat both underlying conditions for the best possible outcomes for your kidneys. Treating just one will leave you vulnerable to long-term kidney problems and damage.

Persistent Proteinuria

If proteinuria lasts a long time, it can be a sign of ongoing kidney damage and could raise your risk of kidney failure. That’s why it’s important to treat the underlying conditions as soon as possible. That way, your kidneys will be less likely to be damaged.

Monitoring the level of protein in your urine is one way that healthcare professionals will track your kidney health when you’re living with IgAN or other chronic kidney diseases. They will ask you to give a urine sample, and then they will send that sample to a lab to look for protein. If your protein levels in your urine tests are going up (or aren’t going down), they may decide to change your treatment for IgAN.

Most doctors look at your proteinuria levels as well as the results of other tests to determine how well your kidneys are working and what treatments you might need. They might take a sample of your kidney tissue (a kidney biopsy), run a variety of blood tests, or do specialized imaging tests to watch how your kidneys function. They can put the results together to give you an overview of your kidney health. If you ever feel like you don’t understand how your kidneys are doing or you want more information on proteinuria, your doctor should be your first call to get the help you need.

Join the Conversation

On MyIgANteam, people share their experiences with IgAN, get advice, and find support from others who understand.

How often do you and your doctor talk about what caused your proteinuria and what makes it get better or worse? Let others know in the comments below.