Understanding Glomerulonephritis: Causes, Types, and Modern Diagnostic Approaches

Glomerulonephritis (GN) isn't a single disease—it's a broad term describing inflammation of the glomeruli, the tiny filtering units within your kidneys responsible for removing waste and excess fluid from the blood. This inflammation can impair kidney function significantly and, if left untreated, may progress to chronic kidney disease or even kidney failure.

Two Main Categories: Primary vs. Secondary GN

Medical professionals classify glomerulonephritis into two major categories based on origin and underlying cause:

Primary Glomerulonephritis

This type originates directly in the kidneys—meaning the immune system mistakenly attacks the glomeruli without an obvious external trigger. Common examples include IgA nephropathy (the most prevalent primary GN worldwide), membranous nephropathy, and minimal change disease. These conditions often present with symptoms like foamy urine (due to proteinuria), swelling in the legs or face (edema), high blood pressure, or unexplained fatigue.

Secondary Glomerulonephritis

In contrast, secondary GN develops as a complication of systemic diseases—conditions that affect multiple organs beyond the kidneys. Leading culprits include diabetes mellitus, hypertension, systemic lupus erythematosus (SLE), and vasculitides such as ANCA-associated vasculitis. In these cases, kidney damage is part of a larger inflammatory or metabolic process—and early detection is crucial to protect renal health while managing the root condition.

Why Pathology Matters: The Critical Role of Kidney Biopsy

Accurate diagnosis of glomerulonephritis hinges on more than just blood tests or urine analysis. A kidney biopsy—a minimally invasive procedure where a small tissue sample is extracted and examined under a microscope—is considered the gold standard. It reveals the exact type of GN, the extent of scarring or inflammation, and helps differentiate between treatable forms and those requiring long-term monitoring.

For instance, identifying IgA deposits confirms IgA nephropathy, while detecting anti-GBM antibodies points to Goodpasture syndrome—a rare but serious autoimmune disorder. This precision directly influences treatment decisions: corticosteroids and immunosuppressants for autoimmune-driven GN, aggressive blood sugar and blood pressure control for diabetic or hypertensive kidney injury, or plasma exchange in life-threatening cases.

From Acute to Chronic: Understanding Disease Progression

Clinically, GN is also categorized by duration and behavior:

• Acute glomerulonephritis often appears suddenly—sometimes after a strep infection—and may resolve fully with prompt care.
• Chronic glomerulonephritis, however, develops gradually over months or years, frequently without noticeable symptoms until significant kidney function is lost. That's why routine screening—including serum creatinine, estimated glomerular filtration rate (eGFR), and urinary albumin-to-creatinine ratio (UACR)—is vital for at-risk individuals, especially those with diabetes, hypertension, or a family history of kidney disease.

Early intervention, personalized therapy, and regular follow-up dramatically improve outcomes. Whether you're newly diagnosed or managing long-standing kidney concerns, understanding your specific GN subtype empowers smarter health decisions—and gives you the best chance at preserving kidney function for years to come.