Glomerular Diseases National Kidney and Urologic Diseases Information Clearinghouse Many diseases affect kidney function by Blood enters the kidneys through arteries attacking the glomeruli, the tiny units that branch inside the kidneys into tiny within the kidney where blood is cleaned. clusters of looping blood vessels. Each Glomerular diseases include many cluster is called a glomerulus, which comes conditions with a variety of genetic and from the Greek word meaning filter. The environmental causes, but they fall into two plural form of the word is glomeruli. There major categories: are approximately 1 million glomeruli, or filters, in each kidney. The glomerulus is • Glomerulonephritis (gloh-MEHR- attached to the opening of a small fluid- yoo-loh-nef-RY-tis) describes the collecting tube called a tubule. Blood is inflammation of the membrane tissue filtered in the glomerulus, and extra fluid in the kidney that serves as a filter, and wastes pass into the tubule and become separating wastes and extra fluid from urine. Eventually, the urine drains from the blood. the kidneys into the bladder through larger • Glomerulosclerosis (gloh-MEHR- tubes called ureters. yoo-loh-skleh-ROH-sis) describes the scarring or hardening of the tiny blood vessels within the kidney. Filtered blood Blood with Although glomerulonephritis and wastes glomerulosclerosis have different causes, they can both lead to kidney failure. What are the kidneys and what do they do? The two kidneys are bean-shaped organs located just below the rib cage, one on each side of the spine. Every day, the two Glomerulus kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of Wastes (urine) urine, composed of wastes and extra fluid. to the bladder In the nephron (left), tiny blood vessels intertwine with fluid-collecting tubes. Each kidney contains Tubule about 1 million Nephron nephrons. Each glomerulus-and-tubule unit is called What are the symptoms of a nephron. Each kidney is composed of about 1 million nephrons. In healthy glomerular disease? nephrons, the glomerular membrane that The signs and symptoms of glomerular separates the blood vessel from the tubule disease include allows waste products and extra water to • albuminuria: large amounts of pass into the tubule while keeping blood protein in the urine cells and protein in the bloodstream. • hematuria: blood in the urine How do glomerular diseases • reduced glomerular filtration rate: interfere with kidney inefficient filtering of wastes from the function? blood Glomerular diseases damage the glomeruli, • hypoproteinemia: low blood protein letting protein and sometimes red blood cells leak into the urine. Sometimes a • edema: swelling in parts of the body glomerular disease also interferes with One or more of these symptoms can be the the clearance of waste products by the first sign of kidney disease. But how would kidney, so they begin to build up in the you know, for example, whether you have blood. Furthermore, loss of blood proteins proteinuria? Before seeing a doctor, you like albumin in the urine can result in a may not. But some of these symptoms have fall in their level in the bloodstream. In signs, or visible manifestations: normal blood, albumin acts like a sponge, drawing extra fluid from the body into the • Proteinuria may cause foamy urine. bloodstream, where it remains until the kidneys remove it. But when albumin leaks • Blood may cause the urine to be pink into the urine, the blood loses its capacity or cola-colored. to absorb extra fluid from the body. Fluid can accumulate outside the circulatory • Edema may be obvious in hands and system in the face, hands, feet, or ankles ankles, especially at the end of the day, and cause swelling. or around the eyes when awakening in the morning, for example. 2 Glomerular Diseases How is glomerular disease What causes glomerular diagnosed? disease? Patients with glomerular disease have A number of different diseases can result significant amounts of protein in the urine, in glomerular disease. It may be the direct which may be referred to as “nephrotic result of an infection or a drug toxic to the range” if levels are very high. Red blood kidneys, or it may result from a disease cells in the urine are a frequent finding that affects the entire body, like diabetes or as well, particularly in some forms of lupus. Many different kinds of diseases can glomerular disease. Urinalysis provides cause swelling or scarring of the nephron or information about kidney damage by glomerulus. Sometimes glomerular disease indicating levels of protein and red blood is idiopathic, meaning that it occurs without cells in the urine. Blood tests measure the an apparent associated disease. levels of waste products such as creatinine and urea nitrogen to determine whether the The categories presented below can filtering capacity of the kidneys is impaired. overlap: that is, a disease might belong If these lab tests indicate kidney damage, to two or more of the categories. For the doctor may recommend ultrasound example, diabetic nephropathy is a form or an x ray to see whether the shape or of glomerular disease that can be placed size of the kidneys is abnormal. These in two categories: systemic diseases, since tests are called renal imaging. But since diabetes itself is a systemic disease, and glomerular disease causes problems at the sclerotic diseases, because the specific cellular level, the doctor will probably also damage done to the kidneys is associated recommend a kidney biopsy—a procedure with scarring. in which a needle is used to extract small pieces of tissue for examination with Autoimmune Diseases different types of microscopes, each of When the body’s immune system functions which shows a different aspect of the tissue. properly, it creates protein-like substances A biopsy may be helpful in confirming called antibodies and immunoglobulins glomerular disease and identifying the to protect the body against invading cause. 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. 3 Glomerular Diseases Systemic lupus erythematosus (SLE) IgA nephropathy is a form of glomerular affects many parts of the body: primarily disease that results when immunoglobulin the skin and joints, but also the kidneys. A (IgA) forms deposits in the glomeruli, Because women are more likely to develop where it creates inflammation. IgA SLE than men, some researchers believe nephropathy was not recognized as a cause that a sex-linked genetic factor may play of glomerular disease until the late 1960s, a part in making a person susceptible, when sophisticated biopsy techniques were although viral infection has also been developed that could identify IgA deposits implicated as a triggering factor. Lupus in kidney tissue. nephritis is the name given to the kidney disease caused by SLE, and it occurs when The most common symptom of IgA autoantibodies form or are deposited nephropathy is blood in the urine, but in the glomeruli, causing inflammation. it is often a silent disease that may go Ultimately, the inflammation may create undetected for many years. The silent scars that keep the kidneys from functioning nature of the disease makes it difficult to properly. Conventional treatment for determine how many people are in the lupus nephritis includes a combination of early stages of IgA nephropathy, when two drugs, cyclophosphamide, a cytotoxic specific medical tests are the only way agent that suppresses the immune system, to detect it. This disease is estimated to and prednisolone, a corticosteroid be the most common cause of primary used to reduce inflammation. A newer glomerulonephritis—that is, glomerular immunosuppressant, mychophenolate disease not caused by a systemic disease mofetil (MMF), has been used instead of like lupus or diabetes mellitus. It appears cyclophosphamide. Preliminary studies to affect men more than women. Although indicate that MMF may be as effective IgA nephropathy is found in all age groups, as cyclophosphamide and has milder side young people rarely display signs of kidney effects. failure because the disease usually takes several years to progress to the stage where Goodpasture’s syndrome involves an it causes detectable complications. autoantibody that specifically targets the kidneys and the lungs. Often, the No treatment is recommended for early first indication that patients have the or mild cases of IgA nephropathy when autoantibody is when they cough up the patient has normal blood pressure and blood. But lung damage in Goodpasture’s less than 1 gram of protein in a 24-hour syndrome is usually superficial compared urine output. When proteinuria exceeds 1 with progressive and permanent damage gram/day, treatment is aimed at protecting to the kidneys. Goodpasture’s syndrome is kidney function by reducing proteinuria a rare condition that affects mostly young and controlling blood pressure. Blood men but also occurs in women, children, pressure medicines—angiotensin- and older adults. Treatments include converting enzyme inhibitors (ACE immunosuppressive drugs and a blood- inhibitors) or angiotensin receptor blockers cleaning therapy called plasmapheresis that (ARBs)—that block a hormone called removes the autoantibodies. angiotensin are most effective at achieving those two goals simultaneously. 4 Glomerular Diseases Hereditary Nephritis— urine and elevated levels of creatinine and Alport Syndrome urea nitrogen in the blood, thus indicating reduced kidney function. High blood The primary indicator of Alport syndrome pressure frequently accompanies reduced is a family history of chronic glomerular kidney function in this disease. disease, although it may also involve hearing or vision impairment. This PSGN is most common in children syndrome affects both men and women, between the ages of 3 and 7, although it but men are more likely to experience can strike at any age, and it most often chronic kidney disease and sensory loss.