Diagnosing Glomerulonephritis in Children

At Hassenfeld Children’s Hospital at NYU Langone, kidney experts, known as nephrologists, are experienced in diagnosing children and adolescents with glomerulonephritis. This condition affects the kidneys, which are two bean-shaped organs located below the rib cage.

The kidneys keep levels of certain minerals, such as sodium and potassium, stable. They also filter waste products and excess fluid from the blood. These substances are then excreted in the urine.

Each kidney contains glomeruli, clusters of microscopic blood vessels that act as filters. The glomeruli allow excess fluid and waste products to pass through the kidneys while retaining blood cells and proteins that the body needs. In children with glomerulonephritis, inflammation occurs in the glomeruli, causing the kidneys to eliminate proteins and blood in urine.

Causes and Risk Factors

When glomerulonephritis occurs suddenly, it is known as an acute episode. A chronic form of the condition develops gradually over a long period of time.

Several infections and conditions can trigger glomerulonephritis. However, in many instances, the cause is unknown.

Children younger than age 10 can develop a temporary form of glomerulonephritis after infection with group A Streptococcus. This bacterium causes strep throat and can lead to inflammation in the kidneys.

Older children and teens who have autoimmune conditions such as lupus may develop glomerulonephritis when antibodies known as immunoglobulin A, which help the body fight infections in the lungs and gastrointestinal tract, accumulate in the kidneys.

Autoimmune conditions that cause inflammation in blood vessels in the kidneys can increase the risk of developing acute glomerulonephritis. One such condition is Henoch-Schonlein purpura, which causes a raised, purple skin rash.

Glomerulonephritis may also occur in children with a rare condition called focal segmental glomerulosclerosis, which causes scarring in some of the glomeruli. This condition can develop when urine flows backwards into the kidneys or when children have frequent urinary tract infections. Risk factors include a low birth weight or having a condition that causes high blood pressure, or hypertension.

Children with acute glomerulonephritis often have dark red or brown urine, which is caused by bleeding in the kidneys. The condition can also lead to urine retention, causing puffiness in the face and less frequent urination. Fluid can build up suddenly in the lungs, causing a cough.

Water and salt retention caused by glomerulonephritis may lead to high blood pressure, as well as swelling in the ankles and feet. Children with glomerulonephritis may also need to urinate more frequently, because the kidneys are not working properly.

Children with severe inflammation due to glomerulonephritis may feel tired. They may also have dry, itchy skin and experience muscle cramps at night. Left untreated, the condition can lead to chronic kidney disease.

The chance of developing chronic glomerulonephritis is greater in people who have an acute episode during childhood.

To diagnose glomerulonephritis, our doctors may perform a physical exam and order several tests.

Physical Exam

A nephrologist performs a physical exam to determine whether your child has any signs of glomerulonephritis. The doctor also takes your child’s blood pressure to determine if he or she has hypertension.

In addition, a specialist asks if your child has had any recent illnesses, such as strep throat, or if your family has a history of autoimmune disorders, because these conditions are linked to glomerulonephritis.

Laboratory Tests

Your child’s doctor may perform blood and urine tests to determine how well the kidneys are working. The samples are sent to a laboratory for analysis.

A creatinine clearance test compares how much creatinine, a waste product that is formed as muscle tissue breaks down, is eliminated in urine versus how much remains in the blood. When the kidneys function normally, more creatinine is found in the urine than in the blood.

A blood urea nitrogen and serum creatinine test reveals how much urea nitrogen and creatinine, substances formed by the breakdown of proteins such as albumin, are in your child’s blood. Higher-than-normal levels of these substances are a sign of poor kidney function.

Doctors also perform tests to detect red blood cell casts, which are cylindrical structures. These develop when the glomeruli bleed, and are often seen in the urine of people with glomerulonephritis.

Testing can also determine if autoantibodies are present. These proteins, which attack healthy tissue instead of bacteria and viruses, may be found in the blood when a child has glomerulonephritis as a result of an autoimmune disorder.

Kidney Biopsy

A kidney biopsy is often recommended to confirm that a child has glomerulonephritis, especially if laboratory tests reveal the presence of red blood cell casts or autoantibodies. This procedure is usually performed in the hospital.

The doctor first numbs a small area of skin on the child’s back with a local anesthetic. Then, guided by an ultrasound device, he or she inserts a thin needle into the kidney to remove a tiny amount of tissue. The tissue sample is sent to a laboratory, where a pathologist, which is a doctor who studies diseases at a cellular level, determines whether it is inflamed—and to what extent.

Our intensivists, doctors in the hospital who care for children with serious medical problems, provide careful monitoring during and after a kidney biopsy to reduce the risk of bleeding. The biopsy results help guide treatment planning.