user: What causes Overview of Kidney Disease in Children ?

assistant: Kidney disease in children can be caused by
                
- birth defects  - hereditary diseases  - infection  - nephrotic syndrome  - systemic diseases  - trauma  - urine blockage or reflux
                
From birth to age 4, birth defects and hereditary diseases are the leading causes of kidney failure. Between ages 5 and 14, kidney failure is most commonly caused by hereditary diseases, nephrotic syndrome, and systemic diseases. Between ages 15 and 19, diseases that affect the glomeruli are the leading cause of kidney failure, and hereditary diseases become less common.1
                
Birth Defects
                
A birth defect is a problem that happens while a baby is developing in the mothers womb. Birth defects that affect the kidneys include renal agenesis, renal dysplasia, and ectopic kidney, to name a few. These defects are abnormalities of size, structure, or position of the kidneys:
                
- renal agenesischildren born with only one kidney  - renal dysplasiachildren born with both kidneys, yet one does not function  - ectopic kidneychildren born with a kidney that is located below, above, or on the opposite side of its usual position
                
In general, children with these conditions lead full, healthy lives. However, some children with renal agenesis or renal dysplasia are at increased risk for developing kidney disease.
                
Hereditary Diseases
                
Hereditary kidney diseases are illnesses passed from parent to child through the genes. One example is polycystic kidney disease (PKD), characterized by many grapelike clusters of fluid-filled cystsabnormal sacsthat make both kidneys larger over time. These cysts take over and destroy working kidney tissue. Another hereditary disease is Alport syndrome, which is caused by a mutation in a gene for a type of protein called collagen that makes up the glomeruli. The condition leads to scarring of the kidneys. Alport syndrome generally develops in early childhood and is more serious in boys than in girls. The condition can lead to hearing and vision problems in addition to kidney disease.
                
Infection
                
Hemolytic uremic syndrome and acute post-streptococcal glomerulonephritis are kidney diseases that can develop in a child after an infection.
                
- Hemolytic uremic syndrome is a rare disease that is often caused by the Escherichia coli (E. coli) bacterium found in contaminated foods, such as meat, dairy products, and juice. Hemolytic uremic syndrome develops when E. coli bacteria lodged in the digestive tract make toxins that enter the bloodstream. The toxins start to destroy red blood cells and damage the lining of the blood vessels, including the glomeruli. Most children who get an E. coli infection have vomiting, stomach cramps, and bloody diarrhea for 2 to 3 days. Children who develop hemolytic uremic syndrome become pale, tired, and irritable. Hemolytic uremic syndrome can lead to kidney failure in some children.  - Post-streptococcal glomerulonephritis can occur after an episode of strep throat or a skin infection. The Streptococcus bacterium does not attack the kidneys directly; instead, the infection may stimulate the immune system to overproduce antibodies. Antibodies are proteins made by the immune system. The immune system protects people from infection by identifying and destroying bacteria, viruses, and other potentially harmful foreign substances. When the extra antibodies circulate in the blood and finally deposit in the glomeruli, the kidneys can be damaged. Most cases of post-streptococcal glomerulonephritis develop 1 to 3 weeks after an untreated infection, though it may be as long as 6 weeks. Post-streptococcal glomerulonephritis lasts only a brief time and the kidneys usually recover. In a few cases, kidney damage may be permanent.
                
Nephrotic Syndrome
                
Nephrotic syndrome is a collection of symptoms that indicate kidney damage. Nephrotic syndrome includes all of the following conditions:
                
- albuminuriawhen a persons urine contains an elevated level of albumin, a protein typically found in the blood  - hyperlipidemiahigher-than-normal fat and cholesterol levels in the blood  - edemaswelling, usually in the legs, feet, or ankles and less often in the hands or face  - hypoalbuminemialow levels of albumin in the blood
                
Nephrotic syndrome in children can be caused by the following conditions:
                
- Minimal change disease is a condition characterized by damage to the glomeruli that can be seen only with an electron microscope, which shows tiny details better than any other type of microscope. The cause of minimal change disease is unknown; some health care providers think it may occur after allergic reactions, vaccinations, and viral infections.  - Focal segmental glomerulosclerosis is scarring in scattered regions of the kidney, typically limited to a small number of glomeruli.  - Membranoproliferative glomerulonephritis is a group of autoimmune diseases that cause antibodies to build up on a membrane in the kidney. Autoimmune diseases cause the bodys immune system to attack the bodys own cells and organs.
                
Systemic Diseases
                
Systemic diseases, such as systemic lupus erythematosus (SLE or lupus) and diabetes, involve many organs or the whole body, including the kidneys:
                
- Lupus nephritis is kidney inflammation caused by SLE, which is an autoimmune disease.  - Diabetes leads to elevated levels of blood glucose, also called blood sugar, which scar the kidneys and increase the speed at which blood flows into the kidneys. Faster blood flow strains the glomeruli, decreasing their ability to filter blood, and raises blood pressure. Kidney disease caused by diabetes is called diabetic kidney disease. While diabetes is the number one cause of kidney failure in adults, it is an uncommon cause during childhood.
                
More information about systemic kidney diseases is provided in the NIDDK health topics:
                
- Lupus Nephritis  - Kidney Disease of Diabetes
                
Trauma
                
Traumas such as burns, dehydration, bleeding, injury, or surgery can cause very low blood pressure, which decreases blood flow to the kidneys. Low blood flow can result in acute kidney failure.
                
Urine Blockage or Reflux
                
When a blockage develops between the kidneys and the urethra, urine can back up into the kidneys and cause damage. Refluxurine flowing from the bladder up to the kidneyhappens when the valve between the bladder and the ureter does not close all the way.