How Many Types of Nephritis Are There? Understanding the Classification and Treatment Approaches
Nephritis, a condition characterized by inflammation of the kidneys, encompasses a wide range of subtypes that vary in cause, progression, and treatment. In clinical practice, especially within pediatric nephrology, the classification system established in November 2000 by the Pediatric Nephrology Group of the Chinese Medical Association in Zhuhai remains widely used. This framework divides nephritis into three major categories: primary, secondary, and hereditary forms—each with distinct features, diagnostic criteria, and management strategies.
Primary Nephritis: Kidney-Specific Inflammatory Conditions
Primary nephritis refers to kidney diseases that originate directly within the renal tissue without being triggered by an external systemic illness. Before diagnosing primary nephritis, doctors must rule out secondary causes such as autoimmune disorders, infections, or metabolic conditions. These diseases primarily affect the glomeruli—the tiny filtering units in the kidneys—and are often identified through abnormal urine tests showing proteinuria (excess protein) or hematuria (blood in urine).
Common Subtypes of Primary Nephritis
Acute glomerulonephritis typically develops after a bacterial infection, most commonly streptococcal throat or skin infections. It presents with sudden onset of swelling, high blood pressure, and reduced urine output. In contrast, rapidly progressive glomerulonephritis (RPGN) is more severe and can lead to kidney failure within weeks if untreated.
Other forms include chronic glomerulonephritis, which progresses slowly over years, often without noticeable symptoms until significant kidney damage has occurred. There's also persistent or isolated hematuria or proteinuria, where patients consistently show blood or protein in their urine but maintain normal kidney function. Management for these conditions usually involves symptomatic care, blood pressure control, and, when necessary, immunosuppressive therapy such as corticosteroids or other agents to modulate the immune response.
Secondary Nephritis: Kidney Inflammation Triggered by Systemic Diseases
Secondary nephritis occurs when kidney damage results from another underlying disease affecting the entire body. Unlike primary forms, treating this type requires addressing the root cause to prevent further renal injury. These conditions are increasingly recognized due to better diagnostic tools and greater awareness of systemic illnesses impacting the kidneys.
Major Causes of Secondary Nephritis
One common example is lupus nephritis, a complication of systemic lupus erythematosus (SLE), an autoimmune disease that can severely damage multiple organs including the kidneys. Another is Henoch-Schönlein purpura (HSP) nephritis, which typically follows a rash and joint pain, mostly seen in children after viral infections.
Hepatitis B-associated nephritis is prevalent in regions where hepatitis B is endemic and often affects younger individuals. Additionally, ANCA-associated vasculitis leads to necrotizing inflammation of small blood vessels, frequently involving the kidneys and lungs. Exposure to certain drugs or toxins—such as nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, or heavy metals—can also induce inflammatory kidney damage. Effective treatment hinges on managing the primary condition, whether through antiviral therapy, immunosuppression, or discontinuation of harmful substances.
Hereditary Nephritis: Genetic Disorders Affecting Kidney Function
Hereditary nephritis stems from genetic mutations passed down through families, leading to structural or functional abnormalities in the kidneys. These conditions often manifest early in life and may progress to chronic kidney disease or end-stage renal failure if not monitored closely.
Key Examples of Inherited Kidney Diseases
The most well-known form is Alport syndrome, caused by mutations in genes responsible for type IV collagen—a critical component of the glomerular basement membrane. Patients often present with persistent hematuria, hearing loss, and eye abnormalities. Over time, many develop proteinuria and declining kidney function.
Another inherited condition is familial recurrent hematuria, also known as thin basement membrane nephropathy, which generally carries a favorable prognosis but requires long-term follow-up to distinguish it from more aggressive forms of glomerular disease. Diagnosis of hereditary nephritis relies heavily on family history, genetic testing, and sometimes kidney biopsy to confirm ultrastructural changes in the filtration barrier.
Early detection and personalized care are essential in slowing disease progression and improving quality of life for patients with any form of nephritis. As research advances, new biomarkers and targeted therapies continue to emerge, offering hope for more effective interventions across all types of kidney inflammation.