Living with chronic kidney disease such as immunoglobulin A nephropathy (IgAN or IgA nephropathy) can involve regular blood and urine tests to evaluate the progression of your kidney disease. One of these tests will assess your estimated glomerular filtration rate (eGFR). A low eGFR can mean your kidney disease is progressing.

Your nephrology team can explain what a declining eGFR means and what steps may help protect your kidney function. Understanding your results can help you make informed decisions about your care.

Understanding Your Glomerular Filtration Rate and IgAN

Inside your kidneys, you have tiny filters that remove wastes, toxins, and extra fluid from your blood. Your body gets rid of these substances when you urinate. The filters are called glomeruli.

A test that examines your glomerular filtration rate looks at how well these filters are working. The higher the number, the more they are filtering. A low glomerular filtration rate means they aren’t filtering as well as they should.

It’s important to note that while it’s possible to test for your actual glomerular filtration rate (GFR), it’s a difficult and expensive test. Instead, most of the time, your doctors will use a formula to estimate your GFR.

Calculating eGFR involves measuring the level of certain substances in your blood. Since your kidneys usually filter these substances, your doctor can tell how well they’re filtering by how much of these are in your bloodstream.

Doctors usually look at your levels of creatinine (a waste product of the breakdown of muscle tissue and proteins) or cystatin C (a protein produced by most cells of the body). GFR calculation also varies depending on your age, sex, and body size and is measured in milliliters per minute per 1.73 square meters of body surface area.

Kidney function generally declines as people get older. This makes eGFR less accurate in people over 70 years old. Your eGFR can also be affected by pregnancy, certain medications, liver or kidney conditions, or other factors.

If any of these apply to you, talk to your nephrology team about other ways to test your kidney function.

What To Do About a Low eGFR

If you have a low eGFR, there are a few things you can do to support your kidneys. You can’t make IgAN go away, but you can make choices that protect your kidneys as much as possible.

Treat IgAN

Talk to a healthcare professional about getting better treatment options for IgAN. In large phase 3 clinical trials, some medications were shown to help slow GFR decline in people with IgAN.

Only your doctor can tell you for sure if these are good options for you. Reach out to them if you’re concerned about your kidneys or you want to know if these treatment options should be part of your plan.

Get Your Blood Pressure Under Control

Hypertension (high blood pressure) can happen when your kidneys are damaged. It can, in turn, lead to more kidney damage. If your blood pressure is high, getting it under control could slow the rate of kidney damage you experience, thus slowing your GFR decline.

Your doctor may prescribe either an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin-receptor blocker (ARB) to help lower your blood pressure. They may also have you limit how much salt you eat, as this can also help with blood pressure problems.

Change Your Diet

Speaking of lowering salt, that and other dietary changes may help protect your kidneys. You may need to meet with a registered dietitian or other nutrition professional to figure out exactly what you should and shouldn’t eat, given the specifics of your body and how kidney disease is affecting it.

In addition to salt, you may need to limit how much phosphorus, potassium, and protein you consume. You’ll want to make sure you continue getting enough calories and healthy fats while you do that, though. This is where a dietitian can be helpful.

Avoid Certain Medications

Some medications can put extra strain on your kidneys, especially if they’re already damaged. These can include antibiotics, common painkillers called nonsteroidal anti-inflammatory drugs (NSAIDs), some diuretics (water pills), as well as some vitamins, herbs, and supplements that you can purchase over the counter.

Have Regular Doctor Appointments

One of the best ways to support your kidneys is to have regular checkups with your nephrologist and to make sure you don’t cancel these unless it’s absolutely necessary. These visits allow you to get personalized kidney care from someone who knows your body and your case.

Personalized care means you’ll get the best treatment options for your specific needs, based on how well your kidneys are working and how IgAN is progressing.

Discuss Your Low eGFR With Your Doctor

If you’re concerned about a low or declining eGFR with IgA nephropathy, talk to your nephrologist. They can review or update your current treatment plan to support your kidney health and slow IgAN progression.