Chronic Kidney (Renal) Disease

Chronic kidney disease (CKD) refers to the kidney’s progressive inability to perform its functions, regardless of the cause. These functions include:

• Cleaning your child’s blood — removing waste, toxins, and extra fluid, and maintaining the right chemical balance
• Regulating vitamins and minerals that help your child’s bones grow and develop
• Releasing hormones and vitamins that regulate the level of red blood cells your child’s body produces, help control blood pressure, and regulate the amount of certain nutrients, such as calcium and potassium

In the past, the phrase “kidney failure” has been used to mean end-stage renal disease (ESRD) — when dialysis or a kidney transplant is necessary because the kidneys have lost around 85 percent of their function. Now the phrase “kidney failure” is falling out of favor and being replaced with chronic kidney disease.

CKD can be used to refer to people in the earliest stages of the disease, people who have moderate degrees of the disease, and people who already have end stage renal disease. This disease is progressive and ends in ESRD. ESRD can be treated effectively by either dialysis or a kidney transplant.

Your child’s stage of CKD is primarily determined by her glomerular filtration rate (GFR) — a measurement of how effectively their kidneys are filtering blood. According to the National Kidney Foundation, there are five stages of chronic kidney disease:

• Stage 1: kidney damage with normal or increased GFR (≥90)
• Stage 2: kidney damage with mild decreased GFR (60-89)
• Stage 3: moderate decreased GFR (30-59)
• Stage 4: severe increased GFR (15-29)
• Stage 5: kidney failure (<15)

Keep in mind that this chart is a guide, and every child may experience symptoms differently. Since chronic kidney disease is progressive, many who have it will eventually reach Stage 5, but there are things we can do to slow the progression and minimize complications.

CKD is common in the United States. In fact there are more people with CKD (around 29 million) than there are with diabetes. In children, however, it’s very rare.

Complications may develop such as:

• High blood pressure
• Anemia (low levels of red blood cells)
• Weak bones
• Malnutrition
• Growth failure
• Nerve damage

Since these complications are largely treatable, it’s important that kidney disease be diagnosed as early as possible.

CKD is challenging to diagnose early because in its earliest stages, it often doesn’t cause visible symptoms. When symptoms do appear, they’re often non-specific, and don’t necessarily indicate a problem with your child’s kidneys. Some of these symptoms include:

• Fatigue
• Problems concentrating
• Trouble sleeping, restless leg syndrome
• Generally feeling unwell
• Fever
• Loss of appetite

Children usually aren’t in pain, unless they have an infection in the kidneys or another organ.

It’s a complicated question. Remember that chronic kidney disease refers to a state in which the kidneys aren’t working properly. This could be due to a malformation, a build-up of scar tissue on the kidneys, or other causes.

About half of all childhood cases of CKD are due to congenital (present at birth) abnormalities of the kidneys or bladder, such as:

• Obstruction to kidneys that can prevent blood from getting to them
• Reflux from bladder back up into kidneys that can cause chronic infection
• Dysplastic kidneys that were never formed correctly and cannot function as they should

For the other half of children with CKD, it may be caused by one or more acquired conditions. Many cases are linked to nephrotic syndrome, a collection of symptoms and signs centered around four major components:

• Protein in urine
• Low levels of protein in the blood since it’s being lost in the urine
• Swelling in the body (edema), particularly around the ankles and eyes. This happens because the proteins that hold water inside your child’s blood vessels are lost in the urine, so water seeps into the body’s tissues
• High cholesterol: to compensate for the low levels of protein, the body makes fat in the form of cholesterol

Focal segmental glomerulosclerosis (FSGS)

Sometimes nephrotic syndrome is caused by a serious condition called focal segmental glomerulosclerosis (FSGS). FSGS causes scarring on the parts of the kidneys that filter the blood. It’s challenging to treat because:

• Its exact causes are unclear.
• It can recur in a newly transplanted kidney, sometimes within hours.

FSGS and other conditions that cause scarring of the kidney tend to worsen over time because scar tissue causes the kidneys to have to work harder, which in turn causes more scar tissue to form.

Children’s researcher Elizabeth J. Brown, MD, has discovered a gene linked with FSGS. These discoveries are critical to determining what causes the disease, and how an effective treatment can be developed.

Other factors that may cause CKD include:

• Some cancers
• Lupus or other autoimmune diseases
• Medication or treatment for other conditions

It’s important to note that the causes of CKD in adults tend to be different. Most often, adult CKD is caused by diabetes, hypertension, and simply aging.

The first step in treating your child is forming an accurate and complete diagnosis. It’s important to remember that diagnosis for chronic kidney disease can be thought of in two ways: diagnostic tests that indicate a problem with your child’s kidneys, and kidney function tests that tell us how well they are working.

Diagnostic tests

Since children with chronic kidney disease rarely show symptoms in the beginning, it often goes undiagnosed until its later stages. Your child’s pediatrician should be monitoring for it during regular check-ups by:

• Performing routine urinalyses and looking for protein in your child’s urine (called “proteinuria”)
• Checking your child’s blood pressure

The diagnostic process often begins when your child’s pediatrician notices protein in your child’s urine during a routine urinalysis, a sign (though not a conclusive one) of kidney disease.

If your child has the signs associated with nephrotic syndrome (NS), their doctor will most likely start them on steroid treatment. The majority (80 to 90 percent) of children respond to steroid treatment, and within eight to 12 weeks, the symptoms disappear. This is known as “minimal change nephrotic syndrome,” and it can come and go, like asthma. Many children outgrow minimal change nephrotic syndrome after a few years.

NS that doesn’t respond to steroid treatment is thought to have a different cause. If your child’s NS doesn’t respond to steroid treatment, their doctors may order further diagnostic tests including:

• Kidney biopsy: A small sample of tissue is taken from through a needle and sent to a lab for analysis. The biopsy may indicate focal segmental glomerulosclerosis (FSGS) or the presence of another acquired disease, such as lupus.
• Kidney ultrasound: A non-invasive test in which a transducer is passed over the kidney producing a picture of the organ on a video screen. The test is used to determine the size and shape of the kidney, and to detect a mass, kidney stone, cyst, or other obstruction or abnormality.
• Nuclear medicine study: Non-invasive, painless tests that can reveal important information about your child's health. Nuclear medicine uses short-lived radiopharmaceuticals and specialized cameras to create images of the human body.

Kidney function tests

There are two main ways to test your child’s kidney functioning: by measuring creatinine level and glomerular filtration rate (GFR).

• Creatinine is a waste product that the body makes in a constant amount (depending on muscle mass) each day. It can only leave the body through the kidneys, so a higher creatinine level indicates decreased kidney functioning. Creatinine level is checked through a simple blood test.
• Glomerular filtration rate test is a measure of how efficiently your kidneys are able to filter your blood.

Other blood tests may be used to check cholesterol level, and for the level of a blood protein called albumin.

How your child feels

In addition to the results of these tests, we also look at your child’s symptoms and how he feels. Despite having a high creatinine level, if he’s feeling well and going to school, it’s probably not time to go on dialysis or have a kidney transplant.

After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we’ll meet with you and your family to discuss the results and outline the best treatment options.

It's entirely natural that you might be concerned right now about your child's health; a diagnosis of chronic kidney disease can be frightening. But you can rest assured that at Boston Children's Hospital, your child is in good hands. Our physicians are bright, compassionate, and committed to focusing on all of your child's needs, not just his condition.

Treatment for stages 1, 2, 3, and 4

If your child is diagnosed in stages 1, 2, or 3 of CKD, they probably won't have many symptoms, but their kidneys won't be functioning the way that they should, which can lead to complications.

If your child's kidneys aren't properly regulating the acid levels in the blood, this may result in a condition called acidosis, which doesn't have any symptoms. We can treat acidosis with bicarbonate, an oral medicine that balances the acid levels.

The kidneys regulate the level of calcium and phosphorous (minerals necessary for bones to continue to grow) in your child's body. If they begin to lose the ability to do this, we can supplement those minerals with activated vitamin D, medicines that prevent the absorption of calcium and phosphorous, and regulating diet.

Your child's blood pressure may start to go up, and if we treat this with blood pressure medication early on, we can minimize the risk of cardiovascular disease as the condition progresses.

If your child's kidneys aren't making erythropoietin (EPO), a hormone that regulates how the body makes red blood cells, she may develop anemia and experience weakness, fatigue, and/or have trouble concentrating. To relieve these symptoms, we may recommend EPO be given as a shot at home, usually weekly or every other week. Many symptoms associated with chronic kidney disease are related to anemia, so this treatment has a very good chance of making your child feel better.

Your child's growth rate may be affected. If this happens, we can give them growth hormones. This is given as a shot every night at home.

If your child is in stage 4, their doctors may also take some steps to get them ready for treatment in stage 5. Often this involves a course of dialysis before transplant.

Treatment for stage 5 CKD (end-stage renal disease)

Stage 5 is defined as end-stage renal disease, at which point your child needs to go on dialysis or have a kidney transplant. Both are effective treatments, and our goal is to transplant virtually all of our patients with ESRD. Around 75 percent of children with ESRD go on dialysis before receiving a transplant.

One of the roles of your child's kidneys is to act as a filter for their blood, making sure that it has the right balance of water and minerals. If your child's kidneys are unable to do this, dialysis is a procedure that can do it for them. Dialysis may be given every night at home, or at a hospital or dialysis center three or four times a week.

In some children, including those with the severe form of FSGS or familial hemolytic uremic syndrome (HUS), the disease causes the kidney to fail almost as soon as it is transplanted. In other cases, it may not be a good time for the family to have the child undergo a transplant. The good news is that a kidney transplant is very rarely an emergency, and never absolutely necessary, because dialysis is such an effective treatment.

Our Division of Nephrology is the largest pediatric nephrology service in the United States. We care for patients with a wide range of kidney disorders, and we are home to the largest Kidney Transplant Program in New England dedicated to caring for children.

Our seven-bed dialysis unit is the only full-service pediatric dialysis unit in New England. If your child requires dialysis, our dialysis nurses, dietitians, tutors, and child life specialists will do everything they can to make sure your child is comfortable during her treatments.

Our compassionate caregivers know that your child is a person, not just a patient, and depending on your particular situation, we provide support services for your child and your family throughout all stages of treatment and recovery.