Glomerular disease is a group of conditions that damage the glomeruli, the tiny filtering units inside your kidneys. Each kidney contains roughly one million of these microscopic clusters of blood vessels, and together they filter about 150 quarts of blood every day. When they’re injured, waste products build up in the blood while essential proteins leak into the urine, setting the stage for serious kidney problems.
What the Glomeruli Actually Do
Think of each glomerulus as a highly selective sieve. Blood flows into a tight ball of capillaries at high pressure, forcing water, salts, and small waste molecules (like creatinine and urea) through the filter wall and into the kidney’s drainage system. That filtered fluid eventually becomes urine. At the same time, the filter holds back larger molecules your body needs, especially proteins like albumin and antibodies.
The filter itself has three layers: the inner lining of the capillaries, a shared basement membrane, and specialized cells called podocytes that wrap around the outside. Podocytes extend tiny finger-like projections that interlock, leaving narrow slits between them. Those slits act as the final checkpoint, blocking proteins by size and electrical charge. When any layer of this three-part barrier breaks down, the kidney starts leaking what it shouldn’t and retaining what it should be clearing.
How the Filter Gets Damaged
Glomerular disease falls into two broad categories. In primary glomerular disease, the immune system or a genetic defect targets the glomeruli directly. In secondary glomerular disease, a systemic condition like diabetes, lupus, or a blood disorder harms the kidneys as part of a wider problem.
The most common mechanism is immune-mediated injury. Antibodies or immune complexes deposit in the glomeruli and trigger inflammation, which damages the delicate filter layers. In other cases, metabolic stress (from high blood sugar, for example) gradually thickens and scars the basement membrane. Genetic mutations affecting the structural proteins of podocytes or the basement membrane can also weaken the barrier, sometimes from birth.
Because podocytes live in a mechanically demanding environment and cannot easily regenerate, even modest injury can become permanent. Once enough podocytes are lost, the remaining cells can’t cover the filter surface, and protein leakage accelerates.
Common Types of Glomerular Disease
IgA Nephropathy
IgA nephropathy is the most common form of glomerulonephritis worldwide. It develops when abnormally shaped IgA antibodies form immune complexes that deposit in the glomeruli, activating inflammation. The disease isn’t caused by infection itself, but infections and other immune triggers can set off the abnormal IgA response. About 10% of kidney biopsies in the United States reveal IgA nephropathy, and that figure rises to 20 to 40% in East Asia and parts of Europe.
Minimal Change Disease
This is the leading cause of nephrotic syndrome in young children, typically between ages 2 and 7. Under a standard microscope, the kidney tissue looks almost normal, which is how the disease got its name. Only an electron microscope reveals the subtle flattening of podocyte foot processes. Most children respond well to treatment, though relapses are common.
Diabetic Kidney Disease
Diabetes is the single largest driver of secondary glomerular damage. Roughly 40% of people with diabetes will develop some degree of kidney disease over their lifetime. In type 2 diabetes, kidney involvement can already be present at the time of diagnosis because the disease often goes unrecognized for years. About 25% of people with type 2 diabetes show early signs of protein leakage within 10 years of diagnosis.
Lupus Nephritis
Systemic lupus can cause the immune system to attack the glomeruli directly. The severity ranges from mild protein leakage to aggressive inflammation that threatens kidney function within months. Treatment intensity depends on how much of the glomerulus is involved.
Symptoms to Recognize
Glomerular disease often develops quietly. Some people have no symptoms at all until routine bloodwork or a urine test catches the problem. When symptoms do appear, the most telling signs relate to what’s leaking through the damaged filter:
- Foamy urine, caused by excess protein spilling into the urine
- Pink or cola-colored urine, a sign of red blood cells passing through the filter
- Swelling (edema), especially around the eyes in the morning, and in the hands, feet, or abdomen later in the day
- High blood pressure, which can be both a cause and a consequence of glomerular damage
- Decreased urine output
- Fatigue, nausea, and muscle cramps, which develop as waste products accumulate in the blood
In children, puffy eyes that get confused with seasonal allergies are often the earliest visible clue.
How It’s Diagnosed
Two simple tests form the foundation. A blood test estimates your glomerular filtration rate (GFR), which measures how efficiently the kidneys are cleaning your blood. A GFR of 60 or above is considered normal, below 60 suggests kidney disease, and 15 or below indicates kidney failure. A urine test checks for albumin, the protein most likely to leak through a damaged filter. A urine albumin result above 30 mg/g signals a problem.
These screening tests identify that something is wrong, but they can’t pinpoint which glomerular disease you have. For that, a kidney biopsy is usually necessary. A small tissue sample is examined under standard and electron microscopes, and special stains can reveal immune deposits, scarring patterns, or structural changes that distinguish one condition from another. The biopsy result guides treatment decisions.
Treatment Approaches
Treatment depends heavily on the underlying cause and how aggressive the disease is. For immune-driven forms like lupus nephritis and IgA nephropathy, the goal is to dial down the immune attack on the glomeruli. This typically involves medications that suppress immune activity, often starting with steroids and adding other immune-suppressing drugs. The intensity and duration vary: some people need only a short course, while others require years of maintenance therapy to prevent flares.
For diabetic kidney disease, the priority shifts to controlling blood sugar and blood pressure, both of which directly reduce the stress on damaged glomeruli. Newer medications originally developed for blood sugar control have shown significant kidney-protective effects in clinical trials, slowing the rate of protein leakage and preserving filtration over time.
Across all types of glomerular disease, blood pressure management is a consistent pillar. High blood pressure accelerates the loss of kidney function regardless of the original diagnosis. Medications that reduce pressure within the glomerular capillaries specifically (not just overall blood pressure) are a standard part of care.
Progression and Long-Term Outlook
Not all glomerular diseases progress at the same pace. Minimal change disease in children often responds completely to treatment, with many children eventually outgrowing it. IgA nephropathy, on the other hand, can smolder for decades. Some people maintain stable kidney function for life, while others gradually lose filtration capacity over 10 to 20 years.
The speed of progression depends on several factors. Persistent protein in the urine is one of the strongest predictors of worsening kidney function, because the leaked protein itself damages the kidney’s drainage tubes downstream. Uncontrolled high blood pressure accelerates decline. People of African descent experience faster progression on average, likely due to a combination of genetic susceptibility and higher rates of hypertension.
When kidney function does decline, it’s measured in stages of chronic kidney disease, from stage 1 (normal GFR with evidence of damage) through stage 5 (kidney failure). Reaching stage 5 means the kidneys can no longer sustain life without dialysis or a transplant. Catching glomerular disease early and managing it aggressively gives you the best chance of staying far from that point.