Nephrotic Syndrome in Children: What You Need to Know

Nephrotic Syndrome in Children

Nephrotic syndrome in children is not a disease, but rather a group of symptoms that usually indicate kidney damage (particularly glomeruli damage) and proteinuria (high levels of protein in the urine). When there is kidney damage, a protein called albumin, which is normally present in the blood, leaks into the urine. Proteins are complex and large molecules, which have numerous significant body functions.  

There are two types of nephrotic syndrome in children. They are:

• Primary – It is the most common type of nephrotic syndrome in children. This condition usually starts and only affects the kidneys. 

• Secondary – This syndrome is usually caused by other health conditions.

Children with nephrotic syndrome are usually referred to a pediatric nephrologist, a specialist who treats kidney diseases. Unfortunately, there are only a few pediatric nephrologists in other parts of the country, so children may need to travel. If traveling with your child is not an option, adult nephrologists can also treat children’s kidney diseases. 

What are kidneys and their function?

There are two kidneys in the body, and they are bean-shaped organs located on each side of the spine and just below the rib cage. The kidneys are filtering organs, which daily filter around 120-150 quarts of blood to produce around 1-2 quarts of urine. The amount of urine produced usually depends on a person’s age. Children tend to produce a lesser amount of urine than adults.

From the kidneys, urine flows to the urinary bladder through the ureters. The urinary bladder is a hollow organ that stores urine. When it is time to urinate, the bladder empties and urine is excreted through the urethra, which is a tubular structure that transports urine and semen out of the body.

Each kidney has a million functional units called nephrons. Each nephron filters a certain amount of blood. The nephron is composed of a filter called the glomerulus, which is attached to a tubule. The glomerulus lets waste products and fluids pass, except for large molecules like proteins and blood cells. The filtered substances pass through the tubule, which removes wastes and returns needed minerals back to the blood. 

Causes of Childhood Nephrotic Syndrome

Nephrotic syndrome in children usually has unknown causes. However, other conditions that can cause glomeruli damage often cause nephrotic syndrome. In children, the most common cause of primary nephrotic syndrome is disease, which is often linked to allergic reactions, infections, tumors, or taking too much over-the-counter medications, such as acetaminophen and ibuprofen. Specific genetic problems in children can also cause primary childhood nephrotic syndrome.

The usual cause of secondary nephrotic syndrome in children is an infection or any underlying disease. The diseases present at birth or congenital diseases may also cause nephrotic syndrome in children. 

1. Primary Childhood Nephrotic Syndrome

The different types of idiopathic childhood nephrotic syndrome are:

• Minimal Change Disease (MCD) - It is a kidney disease characterized by glomeruli damage. It is only visible through an electron microscope. Tiny details are shown better with this microscope compared to any other microscope. MCD is one of the most common causes of nephrotic syndrome in children. However, the cause of MCD is still unknown.

• Focal Segmental Glomerulosclerosis (FSGS) - It is a glomerular disease, which is characterized by sclerosis or scarring in the kidney.

• Membranoproliferative Glomerulonephritis (MPGN) - It is a form of glomerulonephritis, which is caused by a faulty immune response. In this condition, the immune system starts to attack the kidneys' healthy cells as well as impair the normal functioning of the glomeruli. The antibodies produced by the immune system are deposited in the kidney's glomerular basement membrane (GBM).

2. Secondary Childhood Nephrotic Syndrome

Below are some diseases that can cause secondary childhood nephrotic syndrome:

• Streptococcal Infection – Bacterial infection that causes strep throat or untreated skin infections.

• Hepatitis – Inflammation of the liver due to a virus.

• Diabetes – A chronic disease that is associated with elevated levels of glucose (sugar) in the blood.

• Human Immunodeficiency Virus (HIV) – It is a virus that impairs the normal function of the body’s immune system. It causes HIV infection and AIDS (acquired immunodeficiency syndrome).

• Lupus – It is an autoimmune disease, wherein the body’s immune system attacks normal and healthy tissues leading to inflammation of the different organs of the body.

• Henoch-Schonlein Purpura (HSP) – It is a disease that causes inflammation of the small blood vessels.

• Malaria – It is a life-threatening mosquito-borne disease caused by a parasite. Severe complications and death may occur if malaria is left untreated.

• Other Causes – Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and aspirin, and chemical exposure (lithium and mercury).

3. Congenital Diseases and Nephrotic Syndrome in Children

Nephrotic syndrome in 1 to 3-month-old infants is rare. This condition is sometimes called infantile nephrotic syndrome. It can be caused by:

• Genetic disorders (problems that are inherited from the parent's genes to the child)
• Neonatal infections (infections after birth)

Risk Factors

Researchers are still unable to determine which children are more susceptible to developing primary childhood nephrotic syndrome. However, they have found a link between nephrotic syndrome in children and genetics, making it possible to predict the condition in some children. Children are more prone to developing secondary nephrotic syndrome if they have the following risk factors:

• Certain types of infections
• Taking medications
• Diseases that can cause kidney damage

Signs and Symptoms 

• Albuminuria - It is a condition characterized by the presence of albumin in the urine. It is usually a symptom of kidney problems. 

• Hypoalbuminemia - Low levels of albumin in the blood. 

• Edema - It is a medical term used to describe swelling due to excess fluid that is trapped in the body's tissues. Edema is usually seen in the legs, ankles, feet, hands, or face. 

• Hyperlipidemia - It is a term that refers to elevated levels of cholesterol and fats in the blood. 

Some children with nephrotic syndrome may also have the following symptoms:

• Fever
• Irritability
• Lethargy
• Loss of appetite
• Abdominal pain
• Hematuria (blood in urine)
• Diarrhea
• High blood pressure

Complications

• Infections - Proteins normally protect the body against infection. When the kidneys are damaged, the body is more likely to develop an infection since it loses proteins. Certain medications and vaccinations are used to treat and prevent infections.  

• Blood Clots - The flow of blood and oxygen can be blocked by blood clots in the blood vessels. Children are more prone to developing blood clots when they lose proteins through their urine. Healthcare providers usually treat blood clots by giving blood thinners. 

• High Blood Cholesterol - The level of albumin in the blood drops when albumin leaks into the urine. To make up for this low albumin level, the liver makes more albumin. At the same time, more cholesterol is also made. Sometimes, medications are prescribed to lower the blood cholesterol levels in children. 

Diagnosis

Childhood nephrotic syndrome is diagnosed through the following:

• A physical examination
• Medical and family history
• Blood tests
• Urinalysis
• Renal ultrasound (ultrasound of the kidney)
• Kidney biopsy

Treatment

1. Primary Childhood Nephrotic Syndrome

• Control the Immune System - Corticosteroids or prednisone can be prescribed. 

• Remove Extra Fluid - A diuretic may be prescribed to help remove extra fluid and lower the child's high blood pressure.

• Lower High Blood Pressure - There are children with childhood nephrotic syndrome who develop high blood pressure. For this reason, they may need to take medications that can help lower their blood pressure. To control children's high blood pressure, two or more medications are usually prescribed.

2. Secondary Childhood Nephrotic Syndrome

The main aim over here is to treat the underlying cause. The condition can be treated in the following ways: 

• Antibiotics for infections
• Dosing adjustments for the treatment of diabetes, HIV, or lupus
• Changing or stopping the medications responsible for the condition

3. Congenital Nephrotic Syndrome

Medications are not usually effective when it comes to treating congenital nephrotic syndrome. In such cases, most children will need a kidney transplant when they reach 2-3 years old. To keep children healthy while waiting for the transplant, doctors usually recommend the following treatments:

• Diuretics - To help relieve swelling and remove extra fluid.

• Albumin Injections - To make up for the lost albumin in urine.

• Antibiotics - To treat infections. 

• Growth Hormones - To help promote growth and maturity of bones. 

• Dialysis - If the kidneys fail, dialysis can artificially help filter wastes from the blood. 

Prevention

There is no known prevention of childhood nephrotic syndrome when its cause is congenital or idiopathic. 

Diet and Nutrition

Children's sodium intake should be limited. Their diet should be low in cholesterol and saturated fat. Before making any changes in the child's diet, parents or caretakers should first discuss the issue with the doctor.