Getting an IgA nephropathy diagnosis can take time and may involve several tests. The process may start after you notice blood in your urine or a urine test finds blood or protein. Your doctor will use these results to check your kidney health and decide what tests you need next.

At your first visit, your doctor will usually check your blood pressure, since hypertension (high blood pressure) is a common symptom in people with IgA nephropathy. They’ll also check for signs of edema (swelling), especially in the face or ankles.

Based on these findings, your doctor may order more tests to confirm this condition. Here are seven tests that may be used to diagnose IgA nephropathy.

Urine Tests

Urine tests require you to give a sample of your urine (pee). Your kidneys filter waste and expel it in the form of urine, so urine tests can provide important information about how well your kidneys are working.

If you have IgA nephropathy, your urine may look red, brown, or frothy, but it can also look normal. A urine test can find microscopic signs of damage to the glomeruli, tiny blood vessels in the kidneys that filter your blood.

Damage to the glomeruli can cause proteinuria (protein in the urine) or hematuria (blood in the urine).

A urinalysis is often part of routine care and may be the first test to show signs of IgA nephropathy, even if you weren’t being tested for kidney disease. This test is commonly used to screen for many conditions, including infections, kidney problems, and diabetes.

Protein and blood are two substances that may appear in your urine if you have IgA nephropathy. Higher levels can be a sign of damage to the glomeruli, the tiny blood vessels that filter your blood.

However, protein or blood in the urine alone can’t confirm IgA nephropathy, so your doctor may order more tests.

Proteinuria

Proteinuria is a high level of protein in your urine. When the glomeruli are damaged, they no longer work properly to filter your blood, letting protein slip through as a result. That’s why proteinuria is so common in IgA nephropathy.

Urine protein tests often look for a specific type of protein called albumin, which usually stays in the blood when the kidneys are working properly. When albumin is present in urine, it can sometimes make urine look foamy.

High levels of protein in your urine can come from other causes, such as dehydration or temporary illness, which is why further testing is necessary to see if you have IgA nephropathy.

Treatments for IgA nephropathy often focus on reducing protein in the urine, as the severity of proteinuria is a predictor of kidney failure. If proteinuria is persistent even with treatment, it could be a sign that your IgA nephropathy is progressing.

If your IgA nephropathy progresses to kidney failure, you’ll need a kidney transplant or lifelong dialysis.

Hematuria

Hematuria is blood in your urine, which you may or may not be able to see depending on the color. As with proteinuria, damaged glomeruli can cause your kidneys to leak blood into your urine. Even if your urine is its typical color, blood cells can be detected under a microscope.

Hematuria can come from other causes, such as urinary tract infections (UTIs), so you’ll need further tests to confirm if the blood in your urine indicates IgA nephropathy.

Less commonly, your doctor might recommend a 24-hour urine study to monitor your condition if they’ve already detected protein in your urine with testing.

A 24-hour urine study involves collecting your urine in a container every time you pee during a 24-hour period. Once the 24 hours are up, you must return the container to the laboratory.

The goal of a 24-hour urine study is to see how much protein you lose through your urine in that time period.

Blood Tests

Blood samples can also be useful tools to help diagnose IgA nephropathy. Your doctor may use blood tests to check the levels of various substances in your blood and evaluate kidney function.

Creatinine is a waste product made by your muscles. Healthy kidneys filter creatinine from your blood, but levels can rise if your kidneys aren’t working well.

A serum creatinine test measures creatinine in your blood and helps your doctor assess how well your kidneys are working.

High creatinine levels indicate poor kidney function, so they’re a reliable indicator of kidney disease. If your serum creatinine is high, you’ll need more tests to determine if you have IgA nephropathy or another chronic kidney disease (CKD).

Your doctor might recommend a blood urea nitrogen (BUN) test if you have high levels of creatinine in your blood.

This test measures a waste product called urea nitrogen that normally gets filtered out of your bloodstream by your kidneys. Your body creates urea nitrogen when it processes or breaks down protein.

A BUN test can’t definitively diagnose IgA nephropathy, but your doctor will consider the result when recommending other tests.

Cystatin C is a specific protein your kidneys usually filter out of your blood, but it can build up to high levels in your blood if your glomeruli are damaged. Instead of using this number alone, your doctor considers your cystatin C level alongside your serum creatinine to decide which tests come next.

Your estimated glomerular filtration rate (eGFR) tells you how much blood your kidneys are filtering each minute, which helps indicate your kidney disease progression. Your doctor calculates your eGFR using the result of your serum creatinine test along with your age, sex, height, and weight.

A lower eGFR indicates a later kidney disease stage and low kidney function. Healthy kidneys have an eGFR of 90 or higher, while an eGFR between 60 and 89 may still be normal if there are no other signs of kidney disease.

An eGFR lower than 60 for at least three months means your kidneys are damaged. However, some people with IgA nephropathy still have eGFR within a normal range. Your doctor will recommend additional tests to learn more about your kidney function.

Usually, the final and most definitive step in diagnosing IgA nephropathy is a renal (kidney) biopsy. Getting a kidney biopsy is the only way to confirm if you have IgA nephropathy and get a formal diagnosis.

To perform a kidney biopsy, your healthcare provider uses a long needle to remove a small sample of tissue from your kidney. A pathologist examines the sample under a microscope to look for IgA deposits in the glomeruli and signs of kidney damage. IgA is an immune system protein that can build up in the kidneys, causing inflammation and damage to the glomeruli.

Even if all tests leading up to your kidney biopsy have pointed to kidney disease, a kidney biopsy may reveal that you don’t have IgA nephropathy.

Just 10 percent of renal biopsies lead to an IgA nephropathy diagnosis in the United States, compared to 20 percent to 30 percent in Europe and up to 40 percent in East Asia.

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