kidney and urinary tract disorders
Glomerulonephritis
Diagnosis of Glomerulonephritis
Blood tests Urine tests Kidney biopsy Doctors investigate the possibility of acute glomerulonephritis in people who develop symptoms that suggest the disorder. They also investigate the possibility in people whose laboratory test results (which may be done to evaluate nonspecific symptoms or as part of a routine medical evaluation) indicate kidney dysfunction or blood in the urine. Laboratory tests show variable amounts of protein and blood cells in the urine. Blood tests show a high concentration ofureaand creatinine (waste products) in the blood. In people with rapidly progressive glomerulonephritis, casts are often visible in a urine sample that is examined under a microscope. Casts are clumps of red blood cells or white blood cells, caused by damage to the glomerulus and formed by cells sticking together in the tubule. Blood tests usually detect Overview of Anemia . When doctors suspect glomerulonephritis, a Tissue and Cell Sampling is usually done to confirm the diagnosis, help determine the cause, and determine the amount of scarring and potential for reversibility. Kidney biopsy is done by inserting a needle in one of the kidneys under ultrasound or computed tomography (CT) guidance to obtain a small amount of kidney tissue. Although kidney biopsy is an invasive procedure and occasionally can cause complications, it is usually safe. Chronic glomerulonephritis develops gradually, and therefore, a doctor may not be able to tell exactly when it began. It may be discovered when a urine test, done as part of a medical examination, reveals the presence of protein and blood cells in the urine in a person who is feeling well, has normal kidney function, and has no symptoms. Doctors usually do an imaging test of the kidneys, such as ultrasonography or CT. A kidney biopsy is the most reliable way to distinguish chronic glomerulonephritis from other kidney disorders. A biopsy, however, is rarely done in advanced stages. In these cases, the kidneys are shrunken and scarred, and the chance of obtaining specific information about the cause is small. Doctors suspect that the kidneys are shrunken and scarred if kidney function has been poor for a long time and the kidneys appear abnormally small on an imaging test. Additional tests are sometimes helpful for identifying the cause. For example, in the diagnosis of postinfectious glomerulonephritis, a throat culture may provide evidence of streptococcal infection. Blood levels of antibodies against streptococci may be higher than normal or progressively increase over several weeks. Acute glomerulonephritis that follows an infection other than strep throat is usually easier to diagnose because its symptoms often begin while the infection is still obvious. Cultures and blood tests that help identify the organisms that cause these other types of infections are sometimes needed to confirm the diagnosis. When doctors suspect an autoimmune cause for glomerulonephritis, they do blood tests for antibodies directed against some of the body's own tissues (called autoantibodies) and tests that assess the complement system, a system of proteins involved in the body's immune system. 