The kidneys play a critical role in the body: Acting as the body's filtering system, they help control water levels and eliminate wastes through urine (pee). They also help regulate blood pressure, red blood cell production, and the levels of calcium and minerals.
But sometimes the kidneys don't develop properly and, as a result, don't function as they should. Often these problems are genetic and not due to anything a parent did or didn't do.
Many of these problems can be diagnosed before a baby is born through routine prenatal testing and treated with medication or surgery while the child is still young. Other problems may appear later, with symptoms such as urinary tract infections (UTIs), growth problems, or high blood pressure (hypertension).
In some cases, the problems can be severe and require surgical treatment.
The kidneys are like the body's garbage collection and disposal system. Through microscopic units called nephrons, the kidneys remove waste products and extra water from the food a person eats, returning chemicals the body needs (such as sodium, phosphorus, and potassium) back into the bloodstream. The extra water combines with other waste to become urine, which flows through thin tubes called ureters to the bladder, where it stays until it exits through the urethra (the tube that carries urine out of the body from the bladder) when someone goes to the bathroom.
The kidneys also produce three important hormones: erythropoietin, which stimulates the bone marrow to make red blood cells; renin, which helps regulate blood pressure; and the active form of vitamin D, which helps control the calcium balance in the body and maintain healthy bones.
Kidney failure, which is also called renal failure, is when the kidneys slow down or stop properly filtering wastes from the body, which can cause buildups of waste products and toxic substances in the blood. Kidney failure can be acute (sudden) or chronic (occurring over time and usually long lasting or permanent).
Acute kidney injury (sometimes called acute kidney failure) may be due to bacterial infection, injury, shock, heart failure, poisoning, or drug overdose. Treatment includes correcting the problem that led to the kidney injury and, in some cases, dialysis.
The most common kidney diseases in children are present at birth. They include:
Posterior urethral valve obstruction: This narrowing or obstruction of the urethra affects only boys. It can be diagnosed before the baby is born or just after and is treated with surgery.
Fetal hydronephrosis: This enlargement of one or both of the kidneys is caused by either an obstruction in the developing urinary tract or a condition called vesicoureteral reflux (VUR) in which urine abnormally flows backward (or refluxes) from the bladder into the ureters. Fetal hydronephrosis is usually diagnosed before the child is born and treatment varies widely. In some cases the condition only requires ongoing monitoring; in others, surgery must be done to clear the obstruction from the urinary tract.
Polycystic kidney disease (PKD): This is a condition in which many fluid-filled cysts develop in both kidneys. The cysts can multiply so much and grow so large that they lead to kidney failure. Most forms of PKD are inherited. Doctors can diagnose it before or after the child is born. In some cases, there are no symptoms; in others, PKD can lead to UTIs, kidney stones, and high blood pressure. Treatment for PKD varies — some cases can be managed with dietary changes; others require a kidney transplant or dialysis.
Multicystic kidney disease (MKD): This is when large cysts develop in a kidney that hasn't developed properly, eventually causing it to stop working. (While PKD always affects both kidneys, MKD usually affects just one kidney.) Fortunately, the unaffected kidney takes over and most people with MKD will have normal kidney function. MKD usually is diagnosed by prenatal ultrasound before birth. Doctors manage it by monitoring blood pressure and screening for UTIs when needed. Very rarely, surgical removal of the kidney might be necessary.
Renal tubular acidosis: This is when the kidneys do not properly control the amount of acid in the body. It can cause kidney stones and affect a child's growth, but usually can be treated with medications.
Glomerulonephritis: This is an inflammation or infection of the glomeruli, which are parts of the nephrons that contain tiny blood vessels. It can affect the kidney's ability to filter waste and can lead to swelling, blood in the urine, and a reduction in urine production. Some cases can be treated with medication, while others require dialysis or a kidney transplant.
Nephrotic syndrome: This is when the body loses large amounts of protein through the urine, usually because of a change in the nephrons. Most cases are diagnosed after a child is a year old. Swelling of the face, abdomen, and extremities are among the main symptoms, and are often relieved with medication.
Congenital problems with the urinary tract: As a baby develops in the womb, part of the urinary tract can grow to an abnormal size or in an abnormal shape or position. These problems include:
Sometimes a child can have other health problems that affect how well the kidneys function. These can include:
High blood pressure (hypertension): The kidneys control blood pressure by regulating the amount of salt in the body and by making the enzyme renin that, along with other substances, controls the constriction of blood vessels. The many causes of high blood pressure include any of the kidney diseases mentioned above; genetic factors such as the so-called "essential hypertension," which is the most common form of high blood pressure in adults; and obesity, which has become a major factor.
Kidney stones: The result of the build-up of crystallized salts and minerals such as calcium in the urinary tract, kidney stones (also called calculi) also can form after an infection. Kidney stones that are large enough to block the kidney or ureter can cause severe abdominal pain. But most stones usually pass through the urinary tract on their own. In some cases, they need to be removed surgically, or treated with medication or modifications to the diet. Sometimes the first symptoms are pain and blood in the urine. Kidney stones are more common in adults than in kids.
Nephritis. This is any inflammation of the kidney. It can be caused by infection, an autoimmune disease (such as lupus), or an unknown reason. The first symptoms of nephritis usually are high levels of protein and blood in the urine.
Urinary tract infections (UTIs). UTIs are usually caused by bacteria, such as E. coli. Most UTIs occur in the lower urinary tract (in the bladder and urethra) and can cause pain during urination and a fever. Antibiotic treatment should begin as soon as possible so the infection doesn't spread to the kidneys, where it can cause irreversible damage. In babies, UTIs tend to be more common in boys than girls, perhaps because boys are more affected by congenital kidney problems that increase their risk of infection. Later in life, girls are more likely to get UTIs because of their shorter urethras. Bad habits can contribute to UTIs — kids holding it when they need to go to the bathroom, or wiping themselves in the wrong direction after using the toilet (they should wipe from front to back so bacteria from the stool do not get into the urethra). Among teens, girls are more likely to develop UTIs than boys, mostly due to the shorter urethra or sexual activity with a full bladder.
The signs and symptoms of urinary tract or kidney problems vary and include:
If a kidney disease is suspected, the doctor will take a medical history, do a physical exam, and order urine tests, blood tests, imaging studies, or a biopsy to help make a diagnosis. These studies are usually suggested by a nephrologist, a doctor who specializes in the diagnosis and treatment of kidney diseases.
With urinalysis (a type of urine test), the doctor can quickly detect abnormalities (such as too many red blood cells) that may signal inflammation or irritation in the urinary tract. Urinalysis can also detect an of excess white blood cells, which is most commonly associated with bladder and kidney infections.
Certain blood tests tell doctors how well the kidneys are filtering waste products and balancing the bloodstream's chemical makeup.
Two other important diagnostic tools doctors use are blood pressure and growth measurements. Along with the heart, the kidneys are crucial to determining blood pressure. High blood pressure in a child is an important sign that the kidneys need to be evaluated. Accurate growth measurements can provide a clue to diagnosing some kidney diseases because kids with chronic kidney disease often have growth problems.
The doctor may use a kidney biopsy to evaluate kidney function. A biopsy is a procedure in which a small piece of the kidney tissue is removed with a needle. Performed while a child is under anesthesia, it's a simple procedure that can help make an accurate diagnosis of the kidney problem in about 9 out of 10 cases. It's especially helpful in the diagnosis of nephritis and nephrosis.
In addition to standard X-rays, other imaging studies a doctor may use to help diagnose kidney diseases include:
The most commonly used imaging study, an ultrasound is painless and requires no X-ray exposure or special preparation. A renal ultrasound shows details of the anatomy of the kidneys and bladder. It can rule out or diagnose obstructions, developmental abnormalities, tumors, and stones in the kidneys and urinary tract.
A CAT scan is often helpful in revealing the anatomy of the kidneys or bladder and, in some cases, is better than ultrasound for finding kidney stones. It can show if the kidneys have developed properly or if the flow of urine is blocked by a stone or a developmental abnormality.
A renal nuclear scan involves having special radioactive material injected into a vein. The radiation dose is less than that of a simple X-ray. The scan shows how the kidneys compare with each other in size, shape, and function. It also can detect scarring or other evidence of recurrent or chronic kidney infection.
VCUG is commonly used to evaluate the bladder and the ureters. This procedure involves putting a dye into the bladder to see whether there's an obstruction or a reflux of urine from the bladder back up to the kidneys when the child urinates.
Reviewed by: Steven Dowshen, MD
Date reviewed: February 2014
|National Institute of Diabetes and Digestive and Kidney Diseases This group conducts and supports research on many serious diseases affecting public health.|
|National Kidney Foundation (NKF) NKF seeks to prevent kidney and urinary tract diseases, improve the health and well-being of individuals and families affected by these diseases, and increase the availability of all organs for transplantation.|
|Nephron Information Center The Nephron Information Center offers information about how the kidneys work, transplants, and links to other sites.|
|American Association of Kidney Patients (AAKP) The AAKP serves kidney patients and their families by helping them cope with the emotional, physical, and social impact of kidney failure.|
|Chronic Kidney Diseases Kidneys are about the size of your fist and shaped like beans. What happens when this important pair of organs doesn't work well? Find out in this article for kids.|
|High Blood Pressure (Hypertension) High blood pressure, or hypertension, is usually associated with older people. But some kids do have it, and it can be life-threatening if left untreated.|
|Flash Interactive: Body Basics: Kidneys and Urinary Tract The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine.|
|Urine Tests Is your child having a urine culture or urinalysis performed? Find out why urine tests are performed, and what to expect when the doctor orders them.|
|Urine Test: Automated Dipstick Urinalysis Automated dipstick urinalysis results may point to a urinary tract infection (UTI) or injury, kidney disease, or diabetes.|
|Wilms Tumor Wilms tumor is a cancer of the kidneys that usually affects newborns and the very young. Fortunately, most kids with Wilms tumor survive and go on to live normal, healthy lives.|
|Urinary Tract Infections Urinary tract infections (UTIs) are common in kids, but often can be prevented. Early detection and treatment are key.|
|Recurrent Urinary Tract Infections and Related Conditions Recurrent urinary tract infections can cause kidney damage if left untreated, especially in kids under age 6. Here's how to recognize the symptom of UTIs and get help for your child.|
|Urine Test: Microscopic Urinalysis A microscopic urinalysis can help detect a urinary tract infection (UTI), kidney problems, diabetes, or a urinary tract injury.|
|Hypertension (High Blood Pressure) About 1 in 5 Americans has high blood pressure. Although it's more common in adults, hypertension can occur at any age.|
|Kidneys and Urinary Tract The bean-shaped kidneys, each about the size of a child's fist, perform several functions essential to health. Their most important role is to filter blood and produce urine.|
|Kidney Disease Sometimes, the kidneys aren't able to do their job properly. Other than kidney infections, the two most common kidney conditions among teens are nephritis and nephrosis.|
|Kidney Transplant If the kidneys stop working, a person will need either dialysis or a transplant. Get the facts on kidney transplant in this article for teens.|
|When Your Child Needs a Kidney Transplant If your child needs a kidney transplant, you're probably feeling lots of emotions. Fortunately, many kids who undergo kidney transplants go on to live normal, healthy lives.|
|Urinary Tract Infections (UTIs) You probably don't think much about urinating, or peeing. But what if it starts to sting? Find out more in this article for kids.|
|Movie: Urinary System Watch this movie about the urinary system, which produces pee.|
|When Your Child Has a Chronic Kidney Disease Parents of kids who have a chronic kidney disease often worry about what might happen next, how their child feels, and what treatments are likely to be involved. Find answers here.|
|Kidneys and Urinary Tract The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine.|
|Glomerulonephritis With glomerulonephritis, tiny filtering units in the kidneys stop working properly, causing problems like too much fluid in the body and swelling. Most of the time it can be treated. Find out more.|
|Kidney Stones Kidney stones mostly happen to adults, but sometimes teens can get them. Find out what kidney stones are, how to treat them, and ways to help prevent them.|
|Blood in the Urine (Hematuria) Hematuria is pretty common, and most of the time it's not serious. Find out what causes blood in the urine and what to do about it.|
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