CHRONIC KIDNEY DISEASE IN CHILDREN

Introduction

The kidneys are in charge of different functions related to the body’s fluids. As blood passes through the kidneys, waste products are filtered out. The kidneys make sure to retain enough water and other important substances, such as minerals and proteins, that are needed for the body to function properly. The filtered fluid, containing waste products, is expelled from the body as urine.

Like most other organs in the body, the kidneys may become damaged. There are conditions that can cause mild damage, which may resolve when treated properly. Other illnesses can lead to severe (and often permanent) kidney damage that becomes progressively worse — this is called chronic kidney disease.

Around 18 out of every 1 million children develop chronic kidney disease. Those between 6 to 12 years are the most affected, at 32.1% of all pediatric cases, followed by 13 to 17 years of age (28.3%). The following are various causes of chronic kidney disease:

• birth defects
• inherited conditions
• nephrotic syndrome
• infections
• systemic diseases

Causes of Chronic Kidney Disease

During the first four to five years of life, birth defects and inherited conditions are the most common reasons for developing chronic kidney disease. From 5 to 14 years old, nephrotic syndrome and systemic diseases are the predominant cause. Adolescents 15 years and older can develop diseases that lead to inflammation of kidney tissue (glomerulonephritis), which is the most common cause of kidney failure in this age group.

Some babies develop birth defects while growing inside their mother's womb. In this case, kidneys might not completely develop (renal dysplasia), or not even develop at all (renal agenesis). Sometimes, the kidneys form and grow at an unusual position in the body (ectopic kidney). While some of these conditions are inherited, others have no clear cause.

Some commonly inherited kidney conditions are polycystic kidney disease (PKD) and Alport syndrome. In PKD, fluid-filled cysts grow on the kidneys, taking up space and decreasing the kidney’s ability to function. In Alport syndrome, a genetic mutation for collagen causes problems with the eyes, ears, and kidneys.

Nephrotic syndrome is a kidney disease characterized by inflammation of the kidney tissue, causing problems in filtering proteins and minerals from the body’s fluids. It can be due to other kidney conditions, or a consequence of other systemic diseases or infections. 

Two serious kidney infections are hemolytic-uremic syndrome (HUS) and post-streptococcal glomerulonephritis (PSGN). In HUS, small blood vessels intertwined with kidney tissue become inflamed, which can lead to blood clots that block the filtering process. This ultimately decreases the kidney’s function.

In PSGN, a previous streptococcal infection of the skin or throat causes the body to mistakenly target certain kidney cells that look like the streptococcal bacteria. The body unintentionally attacks itself, causing damage to the kidneys.

Chronic kidney failure can also be precipitated by other medical conditions. In systemic lupus erythematosus (SLE), the kidney can also develop inflammation and injury from the immune system. Diabetes can also affect kidneys by increasing the body’s blood pressure and causing blood to flow more rapidly through kidney tissue, making it difficult to filter out fluid and substances.

Diagnosis

Signs and Symptoms

Chronic kidney disease typically develops secondary to another medical condition. Some children are diagnosed while they are being treated for another disease. Signs and symptoms may depend on the primary illness the child has.

Congenital kidney defects may be discovered during routine prenatal ultrasound, or when a healthcare team is assessing a newborn because of other congenital defects. Children with PKD might have an abdominal mass. Obstruction along the urinary tract may present as persistent or recurrent urinary tract infection. Malnutrition and growth failure may also be signs of kidney disease.

Kidney disease directly affecting the functioning kidney tissue, such as glomerulonephritis and nephrotic syndrome, may start out with edema, high blood pressure, and protein or blood in the urine (on urinalysis). As chronic kidney disease progresses, new symptoms such as lack of appetite, vomiting, nausea, itchiness, pallor, easy bruising, more swelling, weakness, fatigue, poor sleep patterns, and bone pains may develop.

Work-up

The healthcare team decides on which specific laboratory and imaging tests are needed on a case-to-case basis. Some commonly requested tests are kidney function tests, like serum creatinine and blood urea nitrogen (BUN). A urinalysis and electrolyte levels may also be taken. A kidney ultrasound or tissue biopsy may be required in some patients.

Management of Chronic Kidney Disease

Chronic kidney disease may or may not be reversible. This depends on many factors. If the cause is reversible, the immediate goal is to treat the underlying illness and reverse the kidney disease.

In other cases, chronic kidney disease may be irreversible. The aim is to prevent any further kidney damage and to optimize kidney function as much as possible. Hypertension, fractures, and anemia are possible consequences of chronic kidney disease and should also be managed. Antihypertensive medications and vitamin D analogs may be prescribed.

Nutrition

The nutritional intake of a child with chronic kidney disease is, in most cases, modified. To maintain as much normal function of the kidneys as possible, there may be a need to increase or decrease nutrients, depending on the type of injury to the kidney and how severe it may be. Note that the recommendations in nutrient intake may differ per person, depending on a lot of variables that the healthcare team accounts for.

Damaged kidneys may have trouble regulating the amount of water that should be retained in the body. Because of this, the daily fluid intake of patients may need to be limited.

Children should continue to consume enough protein to promote physical growth but shouldn’t exceed the recommended daily intake. Too much protein can make it more difficult for the kidneys to function properly. If the child is undergoing dialysis, the amount of protein needed may increase instead. Some examples of good protein sources are milk, eggs, beans, fish, chicken, red meat, and yogurt.

Some cases of chronic kidney disease may require decreased amounts of sodium in the diet. Some food with high amounts of sodium includes processed food and canned food.

In chronic kidney disease, the kidneys may also have trouble filtering potassium properly. The optimal amount of potassium in the body will depend on the healthcare team’s assessment. If potassium levels are too high or too low, there may be changes in the intake of potassium-rich food such as bananas, tomatoes, potatoes, oranges, spinach, and broccoli.

Phosphorus levels may need to be decreased in chronic kidney disease. Phosphorus can decrease the amount of calcium in the bones. Foods that are rich in phosphorus include rice, corn cereals, egg whites, green beans, root beer, and powdered tea or lemonade mixes.

Medications

As mentioned earlier, chronic kidney disease may lead to other medical conditions, which should be prevented or addressed properly.

The kidneys oversee the production of erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells. Kidney disease may affect erythropoietin levels and lead to anemia. Vitamin or iron supplements, erythropoiesis-stimulating agents, or blood transfusions may be needed.

Hypertension is common in patients with chronic kidney disease. Blood pressure may be controlled by decreasing sodium intake and through antihypertensive medications.

Immunization

Most vaccines given to healthy children may also be given to kids with chronic kidney disease. However, children taking immunosuppressive medications should not be given vaccines that contain live viruses, including those for chickenpox and measles.

Psychosocial effects

It may be difficult for children to adapt to routine or everyday life. They may feel ashamed of acne, weight gain, surgical scars, being smaller or shorter than their friends, or losing bladder control and urinating unexpectedly. It may become harder for them to connect and establish genuine relationships with their peers. They may end up with low self-esteem.

In school, the learning process may also be affected because body waste buildup from inefficient kidneys can affect the brain and nerves. Studies have shown that problems in concentration and behavior are common in these cases. Younger kids may have delays in motor or language skills. There may be a limit to the extracurricular activities (sports and exercise) that these children may participate in, depending on a case-to-case basis.

Even after the initial diagnosis and management, regular monitoring of signs and symptoms, kidney function, electrolytes, and urine are still required, especially for severe or potentially irreversible cases. Those requiring dialysis or frequent follow-up consultations may miss a lot of school days.

Managing children with chronic kidney disease may require adjustments in family dynamics. Patients may feel that their condition takes up a lot of effort and time from their family, and thus feel like a burden to them. Younger siblings may also feel frustrated that most of their parents’ attention is focused on their sick sibling.

Support groups can greatly help both the child and the parents (or family) in adjusting to the stress — managing family relationships, maintaining regular monitoring, and other healthcare concerns for the child.

Progression to End-Stage Renal Disease

There is always a possibility that these children could progress to end-stage renal disease (ESRD). This means that kidney function has decreased significantly, to the point where it needs external help. This may be through dialysis or a kidney transplant.

A child with chronic kidney disease who develops anemia, low levels of albumin or high levels of phosphorus, or hypoparathyroidism may be at risk for ESRD. Hypertension can also speed up the transition to ESRD. This highlights the importance of regular monitoring and follow-up consultations with the healthcare team.

Summary

The kidneys are organs in charge of different functions related to the body’s fluids, including filtering out waste products, retaining enough water and minerals, and producing hormones to stimulate red blood cell production in the body. The kidneys may undergo reversible or irreversible damage — chronic kidney disease happens when the damage is continuous and becomes worse, which may become irreversible. There are many conditions that can lead to chronic kidney disease, and treatment will depend on the cause. Physical and psychosocial development of children may be affected due to chronic kidney disease; this can be managed through regular monitoring with the healthcare team and family support groups.

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Sources

• Barakat, A.J., Chesney, R.W., and the American Academy of Pediatrics (2009). Pediatric Nephrology for Primary Care. American Academy of Pediatrics.
• Kliegman, R.M. & St. Geme, J. (2019). Nelson Textbook of Pediatrics, 21st edition. Elsevier.
• Section on Nephrology (2020). Chronic Kidney Disease in Children. American Academy of Pediatrics. Taken from: https://www.healthychildren.org/English/health-issues/conditions/genitourinary-tract/Pages/Chronic-Kidney-Disease-in-Children.aspx
• National Institute of Diabetes and Digestive and Kidney Diseases (2022). Kidney Disease in Children. Taken from: https://www.niddk.nih.gov/health-information/kidney-disease/children
• National Institute of Diabetes and Digestive and Kidney Diseases (2014).Caring for a Child with Kidney Disease. Taken from: https://www.niddk.nih.gov/health-information/kidney-disease/children/caring-child-kidney-disease
• Srivastava, T., & Warady, B.A. (2021). Chronic kidney disease in children: Overview of management. UpToDate. Taken from: https://www.uptodate.com/contents/chronic-kidney-disease-in-children-overview-of-management