When the Filters Fail: Understanding Glomerular Disease
Introduction
Every day, the kidneys filter about 200 quarts of fluid—that's enough to fill a big bathtub. As blood flows through these organs, waste substances and excess water are removed and ultimately exit the body as urine.
The kidneys are in charge of keeping the body in balance by cleansing waste, excess water, and toxins from the blood. One million or so small filtering units called glomeruli pack each kidney—delicate clusters of blood vessels that work much like tiny strainers. The glomeruli play a key role in normal blood pressure, electrolyte levels, and overall body function.
But when they become inflamed or injured, such as with glomerular disease, the filtering process is lost. Waste and protein seep into the urine, fluid builds up in the body, and kidney function begins to decline—sometimes gradually, sometimes abruptly. If untreated, injury can lead to serious kidney complications or kidney failure.
What is Glomerular Disease?
Located on each side of your spine beneath the ribcage, the kidneys are the body’s primary filtering systems. The blood flows into the kidneys through arteries, which diverge into even finer vessels, giving minute looping capillaries known as glomeruli.
The glomeruli empty into tiny tubes called tubules, and the two combined form the kidney’s basic functional elements—nephrons. Each kidney contains approximately one million nephrons that constantly filter the blood, remove waste products, and regulate body fluid and electrolyte balance.
Glomerular disease injures the glomeruli in such a way that they are unable to filter the blood properly. When these tiny vessels are injured, their ability to filter and keep in the bloodstream substances that should not pass through—such as red blood cells and proteins—may be lost, and these substances may leak into the urine.
Albumin is a vital protein that pulls excess fluid in the body into the bloodstream so that it can be filtered out and removed by the kidneys. When albumin is lost in the urine, this process is disrupted, and fluid will instead build up in the body. This will lead to swelling, or edema, which presents itself, particularly of the face, hands, feet, abdomen, and ankles.
Glomerulonephritis vs. Glomerulosclerosis
Glomerulonephritis is an inflammation of the fine membrane tissues in the glomeruli—the filtering units of the kidney that distinguish between waste and excess water, and the blood. The inflammation may disrupt the function of the kidney.
Glomerulosclerosis refers to scarring or irreversible damage to the tiny blood vessels, typically due to longstanding injury or disease. Both disorders can disrupt normal kidney filtering and, over time, lead to reduced kidney function or kidney failure if left untreated.
Both glomerulonephritis and glomerulosclerosis are a result of underlying disease, primarily diabetic kidney disease, which is the leading cause of glomerular damage and overall kidney failure within the United States.
Common Causes & Symptoms
Though most of the diseases that cause glomerular disease are rare, diabetic kidney disease affects more than 1 in 3 U.S. adults who have diabetes, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIH).
Several conditions may lead to glomerular disease, including focal segmental glomerulosclerosis (FSGS)—a disease that scars several of the kidney’s filtering structures. FSGS may be linked to genetic predisposition, autoimmune disorders, or physical stress on the kidneys, such as obesity and sleep apnea. Another common cause is IgA nephropathy, or Berger’s disease, an autoimmune condition.
Symptoms of glomerular disease include:
- High blood pressure.
- Swelling (edema) in the hands and ankles, legs, or around the eyes.
- Weight gain due to the retention of water.
- Antegrade hematuria, or blood in the urine, is often only microscopically detected.
Treatment Options
Treatment for glomerular disease often begins with medicine to control symptoms and monitor disease progression. ACE inhibitors or angiotensin receptor blockers (ARBs) are typically the first line of treatment to lower blood pressure and decrease the amount of protein leaking into the urine—both important in protecting kidney function.
In more serious cases, when kidney function severely declines, kidney transplantation is an immediate option. The University of Illinois Chicago (UIC) has a sophisticated kidney transplant program, which offers patients access to skilled surgical care, specialized treatments, and a multidisciplinary team striving for long-term transplant success.