OVERVIEW

What is IgA?

IgA is the abbreviation for Immunoglobulin A. It is the second most abundant immunoglobulin in serum after Immunoglobulin G (IgG) and serves as a primary antibody against viral or bacterial antigens in the human body.

What is IgA Nephropathy?

IgA nephropathy (IgA nephropathy) is the most common glomerular disease, characterized primarily by the deposition of IgA (an immunoglobulin) in the glomeruli.

IgA nephropathy refers to a group of diseases with a shared immunological feature (IgA deposition), though the clinical manifestations, treatments, and patient outcomes vary significantly.

Additionally, many cases of asymptomatic IgA deposition in the kidneys exist, meaning a large number of undiagnosed IgA nephropathy cases remain unidentified in the general population.

The typical presentation includes recurrent episodes of gross hematuria (appearing as pink or red urine) or microscopic hematuria, which may be accompanied by varying degrees of proteinuria.

IgA nephropathy can occur at any age, with young and middle-aged adults accounting for about 80% of cases. Treatment primarily involves glucocorticoids and immunosuppressants, and patient outcomes vary widely. Those with only hematuria tend to have a better prognosis.

Is IgA Nephropathy Common?

Yes, it is relatively common and the most prevalent glomerular disease in China.

SYMPTOMS

What is hematuria?

Hematuria includes microscopic hematuria and gross hematuria.

Microscopic hematuria refers to urine that appears normal in color to the naked eye but contains a certain number of red blood cells upon microscopic examination. Gross hematuria refers to urine that appears visibly abnormal in color, resembling the color of meat wash water, and may show more pronounced blood coloration in severe cases of bleeding.

Most cases of hematuria are caused by diseases of the urinary system, while a small portion may result from conditions in adjacent organs or systemic diseases.

What are the symptoms and manifestations of IgA nephropathy patients?

There are typically three types of presentations:

• Approximately 40%–50% of patients experience single or recurrent episodes of gross hematuria, usually following an upper respiratory infection. These episodes may be triggered by bacterial tonsillitis or other viral upper respiratory infections; patients who have undergone tonsillectomy may also develop hematuria. During acute episodes, patients may experience low back pain and possibly low-grade fever, resembling symptoms of a urinary tract infection or kidney stones. Most patients experience few episodes of gross hematuria, and recurrence occurs only within a short span of a few years.

• Another 30%–40% of patients have microscopic hematuria (urine appears normal in color but contains red blood cells upon microscopic examination) and mild proteinuria, often incidentally detected during routine physical examinations. In these patients, the duration of the disease is uncertain, and ultimately, 20%–25% will progress to gross hematuria.

• Fewer than 10% of patients present with nephrotic syndrome or rapidly progressive glomerulonephritis, characterized by edema, hypertension, abnormal kidney function, and hematuria. Typically, these patients are not diagnosed early and have a long disease duration.

CAUSES

What is the cause of IgA nephropathy?

The exact cause is unknown. Current research suggests it may be related to infections and genetic predisposition.

Is IgA nephropathy hereditary?

It may have some genetic component.

IgA nephropathy is generally considered sporadic without hereditary tendency. However, studies in the U.S. and Italy have shown higher incidence in certain families, suggesting possible genetic susceptibility. The inheritance pattern is complex, likely involving multiple genes.

Who is commonly affected by IgA nephropathy?

It can occur at any age but is more common in adolescents. Predominant in white males, while no significant gender difference is observed in Asians.

DIAGNOSIS

What tests might be needed when IgA nephropathy is suspected?

Generally, blood and urine tests, liver and kidney function tests, and blood pressure checks are required. Other autoimmune indicators also need to be examined.

The most important test is a kidney biopsy, which involves extracting a small piece of kidney tissue under ultrasound guidance for pathological examination. This is the basis for diagnosis.

However, IgA nephropathy presenting only with hematuria is often benign, with a good prognosis for patients, so kidney biopsy is not universally required. It is only performed when more severe symptoms or progression occur, such as persistent high urine protein levels or elevated serum creatinine concentrations.

Which diseases is IgA nephropathy easily confused with?

• For IgA nephropathy presenting only with persistent hematuria, it needs to be distinguished from hereditary nephritis and thin basement membrane nephropathy.

• In children and young adults, membranoproliferative glomerulonephritis can also cause hematuria and requires attention.

• Kidney disease caused by Henoch-Schönlein purpura has similar manifestations to IgA nephropathy in biopsies, making it difficult to differentiate. Other tests and clinical symptoms are needed for distinction.

TREATMENT

Which department should I visit for IgA nephropathy?

Nephrology.

How is IgA nephropathy treated?

IgA nephropathy is a group of diseases with consistent renal immunological features (primarily IgA deposition), but their specific manifestations, treatments, and patient outcomes vary. General interventions include:

• Blood pressure control;

• For patients with proteinuria, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs);

• Use of glucocorticoids, with or without other immunosuppressants, to treat the underlying inflammatory disease.

What medications do IgA nephropathy patients need? What are the common side effects?

Main treatments include: glucocorticoids and other immunosuppressants, ACEIs, ARBs, and antiplatelet drugs.

• Common side effects of glucocorticoids and immunosuppressants: gastric ulcers, osteoporosis, hypertension, diabetes, etc.

• Common side effects of ACEIs and ARBs: dry cough, hyperkalemia, etc.

Do IgA nephropathy patients need a tonsillectomy?

Except for patients with clear indications for tonsillectomy, current evidence does not support routine tonsillectomy for all IgA nephropathy patients.

Do IgA nephropathy patients need follow-up? How often should they be rechecked after treatment?

Initially, follow-ups are typically every 2 weeks. Once the condition stabilizes, follow-ups can be scheduled every 1–3 months. Routine tests include urinalysis, renal function, and monitoring for medication side effects.

Does IgA nephropathy require long-term medication? When can treatment be stopped?

Patients usually need to take medication consistently for 3–6 months. Once the condition is controlled, or hematuria/proteinuria disappears and test results normalize, medication can be discontinued, with regular follow-ups.

Is IgA nephropathy prone to relapse?

IgA nephropathy encompasses diseases with similar immunological features (primarily IgA deposition), but relapse rates vary by subtype. Post-treatment follow-ups are essential to monitor disease control and medication side effects.

What is the prognosis for IgA nephropathy patients? Can it be fatal?

Most IgA nephropathy patients have a good prognosis, and death is rare. However, up to 50% of patients may slowly progress to kidney failure, often over 20–25 years. Others may enter sustained remission or only exhibit mild persistent hematuria and/or proteinuria.

Is deep-sea fish oil beneficial for IgA nephropathy patients?

Prescription-strength ω-3 polyunsaturated fatty acids (doctor-prescribed fish oil, not over-the-counter supplements) may be tried. Some studies suggest ω-3-rich fish oil benefits IgA nephropathy, especially in patients with significant proteinuria. However, its definitive efficacy requires further large-scale clinical validation.

DIET & LIFESTYLE

What should IgA nephropathy patients pay attention to in daily life and diet?

• Prevent infections: Upper respiratory infections are common, and infections such as tonsillitis, pharyngitis, and enteritis can trigger acute episodes or worsen IgA nephropathy. Pay special attention to staying warm during seasonal changes. Urinary tract infections can also aggravate the condition, so seek medical attention promptly if they occur.

• Avoid overexertion: Excessive physical labor, intense exercise, and staying up late can worsen or cause relapse of the disease.

• Monitor blood pressure: If you have high blood pressure, manage it carefully, as hypertension increases the burden on the kidneys.

• Limit high-protein intake: A diet high in protein can increase kidney workload.

• Exercise moderately: When the condition is not fully under control, avoid intense exercise. Instead, engage in aerobic activities like walking or brisk walking for 20–30 minutes once or twice daily.

• Avoid or use nephrotoxic drugs with caution: Examples include gentamicin, streptomycin, tetracycline, phenylbutazone, phenacetin, paracetamol, and unverified traditional herbal medicines. Always read drug instructions carefully and inform your doctor about your IgA nephropathy.

Can IgA nephropathy patients study and work normally?

Most IgA nephropathy patients have a good prognosis and can work normally when the disease is stable.

Does IgA nephropathy affect fertility? Can patients conceive normally?

Patients with relatively normal kidney function (i.e., normal or near-normal glomerular filtration rate) can generally tolerate pregnancy well and have normal pregnancies and deliveries.

As with most other chronic kidney diseases, female patients with an initial glomerular filtration rate below 70 mL/min, uncontrolled hypertension, or severe lesions on kidney biopsy face an increased risk of disease progression during pregnancy. They should carefully consider pregnancy and are advised to stabilize their condition for 1–2 years before conceiving.

Upon discovering pregnancy or when planning for conception, discontinue angiotensin-converting enzyme inhibitors (ACEIs) and certain immunosuppressive drugs, particularly cyclophosphamide and mycophenolate mofetil, due to potential risks to the fetus.

PREVENTION

Can IgA Nephropathy Be Prevented?

Since the exact cause is unknown, there are no effective preventive measures. When symptoms like hematuria occur, seek medical attention promptly for examination and diagnosis.