IgA nephropathy – Diagnostics – Overview of Information and Clinical Research

Diagnosing IgA nephropathy requires careful testing because this kidney disease often develops quietly without obvious warning signs. Early and accurate diagnosis is essential to start appropriate treatment and slow the progression of the condition.

Introduction: Who Should Undergo Diagnostics

IgA nephropathy, also known as Berger’s disease, is a condition where a protein called immunoglobulin A (IgA) builds up in the kidneys and causes inflammation^[1]. Because this disease can progress silently for many years without noticeable symptoms, knowing when to seek diagnostic testing is crucial for your health.

You should consider getting tested if you notice any changes in your urine, particularly if it appears dark, tea-colored, or cola-colored. This discoloration often appears within a day or two after you’ve had a cold, sore throat, or respiratory infection^[2]. If you see foamy urine, which can indicate protein leaking into your urine, this is also an important sign that warrants medical attention.

Many people discover they have IgA nephropathy during routine medical tests that weren’t specifically looking for kidney problems. A standard urinalysis—a simple test that examines your urine under a microscope—might reveal blood or protein in your urine even when you feel perfectly healthy^[4]. This is why regular check-ups are so important, especially if you have risk factors for kidney disease.

If you experience swelling in your face, hands, feet, or ankles, you should seek medical evaluation. This swelling, called edema, happens when your kidneys cannot properly filter fluids from your body^[2]. Pain in your lower back or sides, where your kidneys are located, is another symptom that should prompt you to see a doctor.

People with a family history of IgA nephropathy or related kidney conditions should be especially vigilant about getting regular kidney function tests. Research suggests there may be genetic factors that increase your risk^[4]. If your parents, siblings, or other close relatives have been diagnosed with IgA nephropathy, you should discuss screening with your healthcare provider even if you don’t have symptoms.

⚠️ Important

Up to 40% of people with IgA nephropathy have no recognizable symptoms when they are first diagnosed^[13]. This makes routine medical testing even more critical, as the disease can quietly damage your kidneys for years before you notice any problems. Don’t wait for symptoms to appear before discussing kidney health with your doctor.

Young and middle-aged adults, particularly men, are more likely to be diagnosed with IgA nephropathy^[4]. However, this doesn’t mean other age groups are immune. The disease can affect anyone, and children can develop it as well. In some countries, particularly in Asia, IgA nephropathy is discovered more frequently because routine urine screening is compulsory for schoolchildren^[5].

Diagnostic Methods to Identify the Disease

When your doctor suspects you might have IgA nephropathy, they will use several different tests to confirm the diagnosis and understand how the disease is affecting your kidneys. The diagnostic process typically starts with simple tests and may progress to more complex procedures depending on what the initial results show.

Urine Tests

The diagnostic journey usually begins with a urinalysis, which examines a sample of your urine. A laboratory technician will look at your urine under a microscope to check for blood cells and protein^[9]. Finding red blood cells in your urine, a condition called hematuria, is one of the most common signs of IgA nephropathy. The presence of protein in your urine, known as proteinuria, indicates that your kidneys are not filtering properly and are allowing protein to leak through.

Your doctor may ask you to collect urine samples over a 24-hour period or provide a single sample to measure the ratio of protein to another substance called creatinine. This measurement, called the urine protein-to-creatinine ratio (UPCR), helps determine how much protein your kidneys are spilling into your urine^[10]. Higher levels of protein in your urine often indicate more severe kidney damage and may influence treatment decisions.

Blood Tests

Blood tests provide important information about how well your kidneys are functioning. Your doctor will check the levels of waste products in your blood, particularly creatinine and cystatin C^[9]. When your kidneys aren’t working properly, these waste products build up in your bloodstream because they’re not being filtered out efficiently.

Another crucial blood test measures your estimated glomerular filtration rate (eGFR), which indicates how much blood your kidneys can filter each minute. This number tells your doctor what stage of kidney disease you might have and helps them monitor whether the disease is getting worse over time. A lower eGFR means your kidneys are having more difficulty doing their job.

Kidney Biopsy

A kidney biopsy is the only way to definitively confirm that you have IgA nephropathy^[9]. During this procedure, a doctor uses a special needle to remove small pieces of kidney tissue, which are then examined under a microscope. This may sound concerning, but it’s a standard procedure that provides essential information about your condition.

The biopsy allows pathologists to see the IgA deposits in your kidney’s filtering units, called glomeruli. They can also assess how much inflammation and scarring has occurred in your kidney tissue. This information helps your doctor understand how advanced the disease is and what treatment approach would be most beneficial for you^[3].

The biopsy results may include something called a MEST-C score, which evaluates specific features of kidney damage visible under the microscope^[10]. This scoring system helps predict how the disease might progress and guides treatment decisions. However, it’s important to remember that everyone’s disease behaves differently, and your individual response to treatment matters more than any score.

Distinguishing IgA Nephropathy from Other Conditions

Your doctor needs to distinguish IgA nephropathy from other kidney diseases that can cause similar symptoms. One condition that looks very similar is IgA vasculitis, which used to be called Henoch-Schönlein purpura. This disease also involves IgA deposits but typically causes a distinctive purple skin rash, joint pain, and abdominal discomfort^[5]. IgA vasculitis is more common in children and generally has a better outlook than IgA nephropathy.

Other kidney conditions that must be ruled out include different types of glomerulonephritis, which are diseases that cause inflammation in the kidney’s filtering units. Some of these conditions require different treatments, so accurate diagnosis is essential. Your doctor may also check for systemic diseases like lupus or other autoimmune conditions that can affect the kidneys^[5].

Additional Imaging and Specialized Tests

Your doctor might order additional tests to get a complete picture of your kidney health. An iothalamate clearance test uses a special contrast agent to track precisely how well your kidneys are filtering waste^[9]. This test provides very accurate information about kidney function, though it’s not needed for everyone.

Imaging tests like ultrasound can show the size and structure of your kidneys, helping doctors identify any physical abnormalities. However, imaging alone cannot diagnose IgA nephropathy because the changes in the kidney tissue are too small to be seen on standard imaging studies. This is another reason why the kidney biopsy remains the gold standard for diagnosis.

Diagnostics for Clinical Trial Qualification

If you’re considering participating in a clinical trial for IgA nephropathy, you’ll need to undergo specific tests that help researchers determine if you’re eligible for the study. Clinical trials are research studies that test new treatments, and they have strict criteria about who can participate to ensure the study results are reliable and meaningful.

Most clinical trials for IgA nephropathy require recent blood and urine tests to confirm your diagnosis and measure your current kidney function. You’ll typically need to provide results showing your eGFR, which tells researchers how well your kidneys are filtering blood. Different trials may have different requirements—some accept participants with relatively good kidney function, while others focus on people whose kidney disease is more advanced^[7].

Your level of proteinuria is particularly important for clinical trial qualification. Researchers often use the urine protein-to-creatinine ratio to measure how much protein is leaking into your urine. Many trials specifically enroll people with higher levels of proteinuria because these individuals are at greater risk of their disease getting worse^[10]. Some studies have no minimum proteinuria requirement, while others only accept participants with levels above a certain threshold, such as 0.5 grams per day.

A kidney biopsy report is almost always required for clinical trial enrollment. Researchers need confirmation that IgA deposits are present in your kidneys and want to understand the extent of kidney damage. The biopsy must usually be from within the past few years, as conditions can change over time. The pathology report may need to show specific features or levels of scarring to meet the trial’s inclusion criteria.

⚠️ Important

Clinical trials use surrogate outcomes for accelerated drug approval, meaning researchers measure changes in markers like proteinuria rather than waiting years to see if kidney failure develops^[7]. This allows new treatments to reach patients faster. However, this also means the long-term effectiveness of these treatments is still being studied.

Blood pressure measurements are standard requirements for clinical trial screening. Uncontrolled high blood pressure can affect both kidney function and study results, so trials typically require your blood pressure to be within a certain range. You may need to be taking specific blood pressure medications, such as ACE inhibitors or ARBs, at stable doses before you can enroll^[8].

Some trials exclude people who have already tried certain treatments. For example, if you’ve recently taken high-dose corticosteroids or other immunosuppressive medications, you might need to wait a certain period before joining a study. This helps researchers understand how the new treatment works without interference from previous medications.

Your overall health status matters for clinical trial eligibility. Trials may exclude people with certain other medical conditions, such as severe heart disease, active infections, or other types of kidney disease. Pregnancy or plans to become pregnant during the study period are typically exclusion criteria because researchers need to ensure the safety of both participants and potential children.

Additional diagnostic tests specific to the treatment being studied may be required. For example, trials testing complement inhibitors might need to check your complement levels in the blood. Studies of new anti-inflammatory drugs might require specific markers of inflammation. Your clinical trial coordinator will explain all the required tests and help you understand what each one measures.

It’s important to understand that meeting the diagnostic criteria for a clinical trial doesn’t mean you’re obligated to participate. You should carefully consider whether the potential benefits outweigh any risks or inconveniences. Clinical trials contribute to medical knowledge that helps future patients, but your primary concern should always be your own health and well-being.

Prognosis and Survival Rate

Prognosis

The outlook for people with IgA nephropathy varies considerably from person to person. The course of the disease is unpredictable—some people experience only minor symptoms with blood in their urine and maintain stable kidney function for decades, while others develop complications such as significant protein loss in their urine and progressive loss of kidney function^[2].

Several factors influence how the disease will progress. The amount of protein in your urine is one of the most important indicators—higher proteinuria levels are associated with faster decline in kidney function. Your kidney biopsy results also provide prognostic information, as more severe inflammation and scarring suggest a greater risk of progression. Blood pressure control plays a critical role; keeping your blood pressure well-managed can significantly slow disease progression^[2].

Some people achieve remission, which means the disease becomes inactive and stops causing further damage. With appropriate treatment, including blood pressure management and medications that reduce proteinuria, many patients can slow or even halt the progression of their kidney disease^[1]. However, there is currently no cure for IgA nephropathy, and lifelong monitoring remains necessary even when the disease appears stable.

Recent research suggests that even patients with lower levels of protein in their urine are at risk of progressing to end-stage kidney disease, emphasizing the importance of early treatment rather than a “watch and wait” approach^[13]. The availability of new disease-specific treatments offers hope for better outcomes than were possible in previous years.

Survival rate

Traditionally, IgA nephropathy progresses slowly, with approximately 25 to 30 percent of people developing chronic kidney failure within 20 years of diagnosis^[5]. This means that the majority of people diagnosed with IgA nephropathy do not progress to kidney failure requiring dialysis or transplant within this timeframe, especially with modern treatment approaches.

About 1 in 10 people with IgA nephropathy may experience acute kidney failure, which can occur as a complication of episodes of visible blood in the urine or due to rapidly progressive disease^[5]. When acute kidney failure happens due to blood in the urine, kidney function usually recovers. However, rapidly progressive forms of the disease may lead to chronic kidney problems if not treated promptly.

It’s important to understand that statistics represent averages across large groups of people and cannot predict what will happen to any individual person. Your own outcome depends on many factors, including how early your disease was detected, how well you respond to treatment, how carefully you manage your blood pressure and overall health, and whether you have other medical conditions that affect your kidneys.

Many people with IgA nephropathy live full, active lives for decades after diagnosis, particularly when they work closely with their healthcare team to monitor and manage the condition. Advances in understanding the disease and the development of new targeted treatments offer increasingly hopeful prospects for people diagnosed today compared to those diagnosed in previous decades^[7].