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What is IgA nephropathy?

IgA nephropathy¹ happens when your immune system attacks your kidneys. It is also known as autoimmune kidney disease and Berger's disease. It is considered an autoimmune disease that affects the kidneys and can run in families, although often there is no family history. The damage done can lead to chronic kidney disease and eventually to kidney failure.

It is the third most common cause of kidney disease, although not as common as diabetic kidney disease. It is called IgA nephropathy because a key part of the disease is your normal IgA antibodies building up excessively in your kidneys.

How common is IgA nephropathy?

Again, IgA nephropathy is the third most common cause of kidney disease. However, it is still considered a rare disease. About 60,000 people² in the US have the disease at any given time.

Who is at risk for IgA nephropathy?

Most patients are diagnosed in their teens through their late thirties. Those most at risk are men, people of Asian or Caucasian ethnicity, and members of the Zuni and Navajo tribes.

Again, the disease is considered rare, and risk factors are as yet poorly understood.

How does IgA nephropathy affect the kidneys?

IgA nephropathy happens when you produce IgA antibodies that have insufficient amounts of a sugar called galactose. This sugar is part of the mechanism which allows your white blood cells to recognize each other.

Because of this, other circulating antibodies attach themselves to the faulty IgA, forming a clump called an immune complex. These clumps become stuck in the glomeruli, the small looping blood vessels inside your nephrons, which are the part of the kidney that actually filters your blood. This, in turn, causes high levels of inflammation and damage.

Your kidneys will leak blood and protein into the urine, and the damage done will cause the slow development of scarring of the nephrons. Eventually, this can lead to kidney failure and the need for a transplant or dialysis.

What are the symptoms of IgA nephropathy?

Many people with IgA nephropathy have had no symptoms for years, and some people may have it and not even know it. The first symptoms, when and if they do occur, include:

  • Blood in the urine, presenting as either pink or dark brown “tea-colored”, which may occur after a cold, sore throat, or respiratory infection.

  • Excessively foamy urine - an indication of excessive protein loss. Often it may be described as the kind of foam you get when you shake a bottle of soft drink.

  • Weakness and fatigue

  • Pain in the lower back or sides

  • Swelling in your hands or feet

  • High blood pressure

IgA nephropathy is sometimes spotted when a urine test is done to check for another disease. The doctor may find blood or protein in your urine and decide to investigate the possibility of kidney damage.

What causes IgA nephropathy?

The cause of IgA nephropathy is poorly understood. We do not yet know why some people produce galactose-deficient IgA antibodies. Because the disease is so rare, it is harder to do the kind of analysis needed to establish the root cause. There may be some genetic links. It may also occur as part of your immune system's response to respiratory or intestinal infections.

Risk factors

There are several risk factors for IgA nephropathy. Most patients are diagnosed in their teens through their late thirties. Risk factors include:

  • Male sex

  • Asian or Caucasian race

  • A family history of either IgA nephropathy or IgA vasculitis³ (The latter condition causes IgA to collect in small blood vessels throughout the body.)

  • Celiac disease

  • HIV infection

  • Cirrhosis of the liver

  • Being a member of the Zuni or Navajo tribe

While there may be some genetic predisposition, it’s thought that a second hit to the immune system is needed before the disease is triggered (e.g., by an infection stimulating your immune system). 

Diagnosis

Kidney disease, in general, is most often diagnosed by detecting blood or protein in the urine. The latter is called albuminuria and means your urine has an unusual amount of albumin, which is a protein typically found in the blood.

Your kidneys typically prevent blood and protein from leaking into the urine, but damage to the glomeruli can prevent this filtering process from working correctly. This means that kidney disease may be found during a routine urine test.

Diagnosis is typically done using urine and blood tests and a medical and family history. Urine tests are done to look for albumin or blood in the urine. Meanwhile, a blood test may be done to estimate your glomerular filtration rate (eGFR), which is a way to estimate how much blood your kidneys are filtering per minute and, thus, how efficiently they are working.

These tests can diagnose kidney disease, but confirming IgA nephropathy requires a kidney biopsy and the examination of tissue under a microscope.

If your doctor orders a biopsy, you will get it done in a hospital or clinic under local anesthesia and light sedation. A small needle will be inserted into the kidney to obtain the sample. Only a biopsy can confirm the presence of IgA deposits in your glomeruli.

Treatment of IgA nephropathy

There is no specific treatment for IgA nephropathy, and scarring from it cannot be repaired. However, many cases resolve themselves before too much damage is done.

If this is not the case, then treatment focuses on slowing the progression of the disease to avoid progression to end-stage kidney disease (kidney failure).

Treatments include:

Antihypertensive medication

IgA nephropathy can cause high blood pressure, so you may be prescribed one of two antihypertensive medications that have also been shown to slow the progress of kidney disease. These are either angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). These tablets help reduce blood pressure and protein leakage and may therefore reduce the chance of permanent kidney damage.

If your blood pressure is still high, you may be given other medications such as calcium channel blockers or beta blockers.

Diuretics

You may be prescribed a diuretic to help your kidneys remove extra fluid from the blood. Kidney problems cause high blood pressure by reducing the efficiency of your kidneys when they filter blood and generate urine, and a diuretic can help compensate for this.

SGLTi

These are a relatively new class of medications that can also help reduce protein leakage from the kidney. They have a mild diuretic and blood pressure-lowering effect as well. 

Other medications

You may be given other medications. These include corticosteroids or cyclophosphamide to reduce inflammation and help "dial down" your immune system or statins to keep cholesterol levels down (IgA nephropathy can elevate cholesterol).

If you are on corticosteroids or cyclophosphamide, these drugs can suppress your immune system, which can make you more vulnerable to infections.

A recently-approved drug that is sometimes used is budesonide.⁴ Budesonide reduces the amount of protein excreted in your urine but is still being studied to establish its impact on disease progression. Budesonide is also an immunosuppressant drug.

However, one issue is that the drug can raise blood pressure, which may cause issues for many patients.

Dietary changes

There is no indication that diet and nutrition play any role in causing NgA nephropathy. However, you may be recommended certain dietary changes to support renal health in general. Typically this means limiting sodium and reducing saturated fat and cholesterol.

Reducing cholesterol is particularly important as IgA nephropathy can cause cholesterol levels to rise.

Tonsillectomy

While it is still under investigation, studies show that tonsillectomy⁵ may slow disease progression. This might seem like a strange connection, but removing the tonsils apparently lowers the amount of galactose-deficient IgA1 produced. The procedure is relatively safe, but again, more research is needed to establish whether this is a good treatment and which patients it might benefit.

Fish oil

There are some indications that taking fish oil may slow the rate of loss of renal function. This appears to be the result of the anti-inflammatory properties of omega-3 fatty acids. Fish oil generally has no adverse effects and has other health benefits.

However, you should still talk to your doctor before taking it, and you should not use it instead of medication unless specifically recommended.

Some experts believe that the right dosage of omega-3 fatty acids may allow for the reduced use of corticosteroids and, thus, a reduction in immunosuppressant effects. However, more research still needs to be done.

Managing IgA nephropathy

As already mentioned, your doctor may recommend you reduce dietary sodium, fat, and cholesterol. Most people with IgA nephropathy can lead a normal life for many years, although eventually (typically after 20 to 25 years), there is a risk of kidney failure.

If you are on immunosuppressant drugs, you should attempt to avoid active infection, not be around people who are sick, and consider wearing a well-fitting protective mask if there is something "going around."

Some people experience chronic fatigue that can interfere with everyday activities. Others may have no symptoms at all other than episodes of blood in the urine.

The disease progresses slowly in most cases, and many people never experience kidney failure.

Your doctor may recommend you monitor your blood pressure at home. Many people benefit from joining a support group in their area.

If your disease progresses to end-stage kidney disease, you may need to go on dialysis. Follow the instructions of your care team, especially limiting fluid consumption. Some people with IgA nephropathy are candidates for a kidney transplant if a compatible organ can be found.

You should have your urine tested regularly to check the progression of the disease. Some people may find it goes into complete remission and that they can stop taking medication, although it is a good idea to continue with regular screening, just in case.

Pregnancy can cause significant complications for people with IgA nephropathy, potentially resulting in renal insufficiency that can cause poor pregnancy outcomes and worsen your prognosis. However, if you have a good renal function and low blood pressure, you can have a successful pregnancy.

Talk to your doctor if you are attempting to conceive, and make sure that you have a care team experienced in managing pregnancy in people with chronic kidney disease. Your medications may need to be changed once you’re pregnant as they may cause harm to the fetus.

Complications associated with IgA nephropathy

IgA nephropathy can lead to both acute and chronic kidney failure. It can also cause various other complications, including:

  • High blood pressure

  • Nephrotic syndrome. This is a collection of symptoms indicating kidney damage, which include elevated protein in your urine, reduced protein in your blood, high cholesterol, and fluid retention.

  • Cardiovascular problems

  • Henoch-Schönlein purpura,⁶ also called IgA vasculitis. This means the small blood vessels in your skin, joints, intestines, and kidneys become inflamed and bleed. The key sign is red or purple spots on the skin. But it can also cause symptoms including headache, fever, loss of appetite, cramping and abdominal pain, joint pain, hives, bloody diarrhea, and painful menstruation.

The link between IgA nephropathy and IgA vasculitis is particularly strong, and it appears some of the same genes are involved in both. Taking steps to slow the progression of your disease can help slow these symptoms.

Most people with IgA nephropathy will need medication to treat high blood pressure.

When to see a doctor

You should always see a doctor if you have blood in your urine or if your urine is discolored. However, be aware that blood in your urine is more likely a sign of something much more common and less serious, such as a urinary tract infection or a kidney stone.

Many cases of IgA nephropathy are discovered while your doctor is looking for something else. However, if you have bloody or foaming urine and are also experiencing unusual fatigue, kidney disease of some kind should be suspected.

People with IgA nephropathy should see their doctor regularly to have tests to monitor their kidney function.

The lowdown

Autoimmune kidney disease or IgA nephropathy is a rare condition where a deficiency in your immune system, specifically in the production of certain antibodies, can cause damage to your kidneys. This condition has no specific treatment, although significant research is being done. Fortunately, most patients are able to lead a normal life with it for many years, and in some cases, it goes into remission on its own.

People with IgA nephropathy may need to take medications that suppress their immune system and thus have to be careful about infection. Despite this, the condition can typically be managed for a long time.

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