Key takeaways

  • IgAN and IBD are both autoimmune conditions, and research indicates a strong association between them, with people who have IgAN having a higher risk of developing IBD.
  • IBD can negatively impact kidney health in people with IgAN, increasing the risk of progression to end stage renal disease due to more severe inflammation and structural damage in the kidneys.
  • The gut’s immune function may play a role in the development of IgAN in people with IBD because chronic intestinal inflammation may interfere with immune balance and contribute to IgA buildup in the kidneys.

IgA nephropathy (IgAN) is a condition in which the body produces higher-than-normal amounts of an abnormal antibody called galactose-deficient immunoglobulin A1 (IgA1).

In some people, this abnormal IgA can trigger the immune system to create autoantibodies, which are antibodies that target other antibodies. These immune complexes circulate in the bloodstream and can settle in the kidneys’ filtering units, known as glomeruli.

Over time, these deposits may interfere with how the kidneys filter blood, leading to inflammation and gradual kidney damage. One of the earliest and most common signs of this process is blood in the urine.

Inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, are also autoimmune conditions. In IBD, the immune system mistakenly attacks the gastrointestinal tract, causing ongoing inflammation. This can lead to symptoms like abdominal pain, intestinal bleeding, lack of nutrient absorption, and a higher risk of gastrointestinal cancers.

Research shows a strong association between IgAN and IBD. People with IgAN have about a 300% higher risk of developing IBD compared with the general population. There’s also evidence suggesting that IBD may play a role in the development of IgAN, although the reverse relationship is less clear.

One possible explanation lies in the gut’s role in immune function. About 70% of the immune system is located in the gut, within gut-associated lymphoid tissue (GALT). Chronic intestinal inflammation may disrupt the typical immune balance, increasing the chances that abnormal immune cells form and eventually contribute to IgA buildup in the kidneys.

For people with IgAN, having IBD is linked to a higher risk of kidney disease progression, including progression to end stage kidney disease. Kidney biopsies in these people often show more severe inflammation and structural damage compared with those who don’t have IBD.

IBD itself may also affect kidney health in other ways. Factors such as dehydration, kidney stone formation, and complications related to IBD-associated surgeries can place additional strain on the kidneys.

Taken together, these effects can increase the overall burden on kidney function and may contribute to worse long-term kidney outcomes.

Treatment approaches for IgAN and IBD differ, but both focus on managing inflammation, reducing complications, and protecting long-term organ health.

IgA nephropathy

Treatment for IGAN often begins with supportive care focused on protecting kidney function. This typically includes:

  • managing blood pressure
  • reducing protein in the urine (proteinuria)
  • moderating sodium and protein intake
  • staying well hydrated
  • exercising regularly
  • managing cholesterol levels
  • avoiding smoking

Medications such as ACE inhibitors or angiotensin receptor blockers (ARBs) are commonly used to lower pressure within the kidney’s filtering units.

In people at higher risk of disease progression, doctors may consider immunosuppressive treatments, including corticosteroids or more targeted immunomodulating therapies.

Newer medications, such as sibeprenlimab and pegcetacoplan, aim to target specific pathways involved in the disease process.

Inflammatory bowel disease

Managing IBD often starts with simple, supportive steps like eating well, staying hydrated, and reducing stress. The choice of treatment depends on how severe the disease is.

Mild IBD may respond to corticosteroids or gut-targeted anti-inflammatory medications. Moderate to severe disease often requires biologic therapies, which work by directly interrupting the immune process that drives ongoing inflammation.

Preparing questions ahead of time can help you make the most of your appointments and better understand how IgAN and IBD may affect your health.

You may want to ask:

  • What symptoms require urgent evaluation? For example, blood in the urine, ongoing abdominal pain, changes in bowel habits, or unexplained weight loss.
  • What lifestyle changes can support both kidney and gut health?
  • Should I be screened for IgAN if I have IBD, or vice versa?
  • Which specialists should be involved in my care? For example, a nephrologist, gastroenterologist, or other providers.
  • What are the potential benefits and risks of immunosuppressive therapy?
  • What could happen if IgAN or IBD goes untreated?

Dr. Aaron R. Block is a ABMS certified physician specializing in family medicine and women’s midlife health. He is the CEO, Co-Founder, and practicing physician at The Cove Concierge Medicine in Castle Rock, CO.