What is glomerular disease?
Your kidneys may be small, but they perform many vital functions that help maintain your overall health, including filtering waste and excess fluids from your blood. Your kidneys have about one million tiny filter units called nephrons. Each nephron has a glomerulus, so that means there are over one million of them too. More than one glomerulus are called glomeruli. Glomeruli work like strainers used in cooking. While blood moves through them, they let waste and extra water pass into the nephrons to make urine. At the same time, they hold back the protein and blood that your body needs. Many diseases affect kidney function by attacking the glomeruli. When the glomeruli become damaged and cannot do their job, it is called glomerular disease. Glomerular diseases include many conditions with many different causes.
How do glomerular diseases interfere with kidney function?
Glomerular diseases damage the glomeruli, letting protein and sometimes red blood cells leak into the urine. Sometimes a glomerular disease also interferes with the clearance of waste products by the kidney, so they begin to build up in the blood. In normal blood, albumin acts like a sponge, drawing extra fluid from the body into the bloodstream, where it remains until the kidneys remove it. But when albumin leaks into the urine, the blood loses its capacity to absorb extra fluid from the body. Fluid can accumulate outside the circulatory system in the face, hands, feet, or ankles and cause swelling.
What are the symptoms of glomerular disease?
· albuminuria: large amounts of protein in the urine
· hematuria: blood in the urine
· reduced glomerular filtration rate: inefficient filtering of wastes from the blood
· hypoproteinemia: low blood protein
· edema: swelling in parts of the body
One or more of these symptoms can be the first sign of kidney disease. But how would you know, for example, whether you have proteinuria? Before seeing a doctor, you may not. But some of these symptoms have signs, or visible manifestations:
· Proteinuria may cause foamy urine.
· Blood may cause the urine to be pink or cola-colored.
· Edema may be obvious in hands and ankles, especially at the end of the day, or around the eyes when awakening in the morning, for example.
How is glomerular disease diagnosed?
The first clues are the signs and symptoms. Blood tests will help your healthcare provider tell you what type of illness you have and how much it has hurt your kidneys.
A simple test of your urine can confirm if there is blood or protein in the urine.
In some cases, a test called a kidney biopsy may be needed. In this test, a tiny piece of your kidney is removed with a special needle, and looked at under a microscope. A biopsy will help your healthcare provider plan the best treatment for you.
What causes glomerular disease?
A number of different diseases can result in glomerular disease. It may be the direct result of an infection or a drug toxic to the kidneys, or it may result from a disease that affects the entire body, like diabetes or autoimmune diseases like lupus. Sometimes glomerular disease is idiopathic, meaning that it occurs without an apparent associated disease.
Autoimmune Diseases
When the body’s immune system functions properly, it creates protein-like substances called antibodies and immunoglobulins to protect the body against invading organisms. In an autoimmune disease, the immune system creates autoantibodies, which are antibodies or immunoglobulins that attack the body itself. Autoimmune diseases may be systemic and affect many parts of the body, or they may affect only specific organs or regions. Examples of Autoimmune diseases are;
Systemic lupus erythematosus (SLE) affects many parts of the body: primarily the skin and joints, but also the kidneys. Lupus nephritis is the name given to the kidney disease caused by SLE, and it occurs when autoantibodies form or are deposited in the glomeruli, causing inflammation. Ultimately, the inflammation may create scars that keep the kidneys from functioning properly..
Goodpasture’s Syndrome involves an autoantibody that specifically targets the kidneys and the lungs. Often, the first indication that patients have the autoantibody is when they cough up blood. But lung damage in Goodpasture’s Syndrome is usually superficial compared with progressive and permanent damage to the kidneys. Goodpasture’s Syndrome is a rare condition that affects mostly young men but also occurs in women, children, and older adults.
IgA nephropathy The most common symptom of IgA nephropathy is blood in the urine, but it is often a silent disease that may go undetected for many years. The silent nature of the disease makes it difficult to determine how many people are in the early stages of IgA nephropathy, when specific medical tests are the only way to detect it. This disease is estimated to be the most common cause of primary glomerulonephritis—that is, glomerular disease not caused by a systemic disease like lupus or diabetes mellitus.
Hereditary Nephritis—Alport Syndrome
The primary indicator of Alport syndrome is a family history of chronic glomerular disease, although it may also involve hearing or vision impairment. This syndrome affects both men and women, but men are more likely to experience chronic kidney disease and sensory loss. Men with Alport syndrome usually first show evidence of renal insufficiency while in their twenties and reach total kidney failure by age 40. Women rarely have significant renal impairment, and hearing loss may be so slight that it can be detected only through testing with special equipment. Usually men can pass the disease only to their daughters. Women can transmit the disease to either their sons or their daughters. Treatment focuses on controlling blood pressure to maintain kidney function.
Infection-related Glomerular Disease
Glomerular disease sometimes develops rapidly after an infection in other parts of the body.
Acute post-streptococcal glomerulonephritis (PSGN) can occur after an episode of strep throat or, in rare cases, impetigo (a skin infection). PSGN can bring on sudden symptoms of swelling (edema), reduced urine output (oliguria), and blood in the urine (hematuria). Tests will show large amounts of protein in the urine and elevated levels of creatinine and urea nitrogen in the blood, thus indicating reduced kidney function. High blood pressure frequently accompanies reduced kidney function in this disease.
PSGN is most common in children between the ages of 3 and 7, although it can strike at any age, and it most often affects boys. It lasts only a brief time and usually allows the kidneys to recover. In a few cases, however, kidney damage may be permanent, requiring dialysis or transplantation to replace renal function.
Bacterial endocarditis, infection of the tissues inside the heart, is also associated with subsequent glomerular disease. Treating the heart infection is the most effective way of minimizing kidney damage. Endocarditis sometimes produces chronic kidney disease (CKD).
HIV, the virus that leads to AIDS, can also cause glomerular disease. Between 5 and 10 percent of people with HIV experience kidney failure, even before developing full-blown AIDS. HIV-associated nephropathy usually begins with heavy proteinuria and progresses rapidly (within a year of detection) to total kidney failure.
Sclerotic Diseases
Glomerulosclerosis is scarring (sclerosis) of the glomeruli. In several sclerotic conditions, a systemic disease like lupus or diabetes is responsible.
Diabetic nephropathy is the leading cause of glomerular disease and of total kidney failure in the United States. Kidney disease is one of several problems caused by elevated levels of blood glucose, the central feature of diabetes. In addition to scarring the kidney, elevated glucose levels appear to increase the speed of blood flow into the kidney, putting a strain on the filtering glomeruli and raising blood pressure.
Diabetic nephropathy usually takes many years to develop. People with diabetes can slow down damage to their kidneys by controlling their blood glucose through healthy eating with moderate protein intake, physical activity, and medications. Blood pressure medications called ACE inhibitors and ARBs are particularly effective at minimizing kidney damage and are now frequently prescribed to control blood pressure in patients with diabetes and in patients with many forms of kidney disease.
Focal segmental glomerulosclerosis (FSGS) describes scarring in scattered regions of the kidney, typically limited to one part of the glomerulus and to a minority of glomeruli in the affected region. FSGS may result from a systemic disorder or it may develop as an idiopathic kidney disease, without a known cause. Proteinuria is the most common symptom of FSGS, but, since proteinuria is associated with several other kidney conditions, the doctor cannot diagnose FSGS on the basis of proteinuria alone. Biopsy may confirm the presence of glomerular scarring if the tissue is taken from the affected section of the kidney..
Other Glomerular Diseases
Membranous nephropathy, also called membranous glomerulopathy, is the second most common cause of the nephrotic syndrome (proteinuria, edema, high cholesterol) in U.S. adults after diabetic nephropathy. Diagnosis of membranous nephropathy requires a kidney biopsy. 75 percent of cases are idiopathic, which means that the cause of the disease is unknown. The remaining 25 percent of cases are the result of other diseases like systemic lupus erythematosus, hepatitis B or hepatitis C infection, or some forms of cancer. Drug therapies involving penicillamine, gold, or captopril have also been associated with membranous nephropathy.
Minimal change disease (MCD) is the diagnosis given when a patient has the nephrotic syndrome and the kidney biopsy reveals little or no change to the structure of glomeruli or surrounding tissues when examined by a light microscope. Tiny drops of a fatty substance called a lipid may be present, but no scarring has taken place within the kidney. MCD may occur at any age, but it is most common in childhood
