Chronic Kidney Disease
The kidneys perform a variety of functions to maintain health and promote normal growth and development in children. One of these core functions is to filter the blood, to both maintain normal concentrations of certain electrolytes (like sodium and potassium) and minerals (like calcium and phosphorus), and to eliminate certain substances that at high levels could be harmful. Under normal circumstances, an infant is born with 2 kidneys and each kidney has approximately 1 million filters (known as nephrons or glomeruli). However, some children are born with a significantly reduced number of filters and others, for a variety of reasons, suffer permanent damage to these filters. These children have Chronic Kidney Disease (CKD). CKD can be mild, moderate, or severe. However, it is progressive, meaning that the degree of reduced kidney function gets worse over time. The rate of decline though varies greatly from person to person, often depending upon the cause. Some persons progress from mild CKD to dialysis in a matter of months, whereas others will take years or even decades.
What the Kidneys Do
- Clean the blood, including removing waste, toxins, and extra fluid and maintaining the right chemical balance.
- Regulating vitamin D and the concentration of calcium and phosphorus in the blood. The kidneys thus make sure bones are strong and grow properly.
- Regulate hormones that are important for normal growth.
- Regulate blood pressure.
- Produce a hormone that regulates the production of red blood cells.
Thus, children with CKD can have problems with growth, high blood pressure, anemia, and abnormal bone development.
How is Kidney Function Measured?
Kidney function is usually measured by monitoring the concentration in blood of a substance called creatinine. Creatinine is produced by normal metabolism of muscle and is not toxic. However, it is only eliminated from the body by the kidneys and thus its concentration in blood can be used to estimate how well the kidneys are eliminating waste.
What Are the Stages of CKD
The normal concentration of creatinine in blood varies by age and this concentration can be used to estimate the glomerular filtration rate (GFR), a measurement of how effectively the kidneys are filtering blood.
- Stage 1 CKD (GFR > 90): Damaged kidneys but normal kidney function. Patients at this stage sometimes have hypertension but generally have no other symptoms.
- Stage 2 CKD (GFR 60-89): At this stage, abnormalities in blood phosphorus and a hormone related to bone metabolism (parathyroid hormone or PTH) may be seen. Diet changes may be prescribed. Some children may demonstrate slow growth.
- Stage 3 CKD (GFR 30-59): Anemia often develops and problems with bone metabolism worsen.
- Stage 4 CKD (GFR 15-29): High potassium and accumulation of acids in the blood may be seen.
- Stage 5 CKD (GFR < 15): Patients at or near need for dialysis or kidney transplant.
How Will CKD Affect My Child’s Life and What Treatments Will Be Necessary?
As noted, only children with advanced CKD will feel tired or have other significant symptoms. Children with CKD must visit their pediatric nephrologist on a regular basis and have blood and urine testing. Changes in kidney function that require modifications in diet or start of medication are usually only evident with blood work results. Fortunately, the problems that do develop all have treatments that allow children with CKD to lead active lives and remain healthy as kidney function declines. These problems and their treatments include:
- Growth: Some children with CKD do not grow or gain weight well. In some cases a nutritional supplement will be prescribed. If growth rate is very slow, growth hormone may be prescribed. Growth hormone is given as a shot under the skin (much like an insulin shot) once a day.
- Bone problems: Bone is made hard with calcium and phosphorus. The kidneys help regulate the amount of calcium and phosphorus in the blood. In particular, with early stages of CKD, phosphorus can build up to higher than normal levels and impair normal development of the bones. There is phosphorus in many foods, particularly dairy products, and children with CKD are usually asked to follow a diet low in phosphorus. As CKD advances, phosphorus will build up even with a low phosphorus diet. Thus, children with advanced CKD are usually prescribed medication to take with meals that partially binds the phosphorus in their food. Finally, as CKD worsens, children with CKD are usually prescribed a special kind of vitamin D.
- Acid buildup: Proteins in diet are broken down by the body and this process produces a small amount of acid. The kidneys eliminate these acids, and as CKD worsens these can build up and affect growth and normal bone development. As a result, some children with CKD will be prescribed bicarbonate medication to neutralize these acids.
- Hypertension: The kidneys are a prime regulator of the blood pressure and some children with CKD will develop hypertension. A low salt diet and blood pressure medication may be prescribed.
- Anemia: The kidney makes a hormone (erythropoietin, also known EPO) that regulates the body’s production of red blood cells. Children with advancing CKD often develop anemia. Fortunately, EPO is available to be given as a shot under the skin, usually every week or every other week.
- Dialysis or kidney transplantation: As children reach stage 5 CKD, dialysis or kidney transplant will be necessary to maintain optimal health. The goal of every child with stage 5 CKD is a kidney transplant, though approximately 75% of children first have a course of dialysis as they prepare and await a transplant.
A team of professionals is available to help you and your child with CKD. These include:
- Pediatric Nephrologist
- Pediatric Nephrology Nurses: As children with CKD reach stage 3, they and their families are eligible for Reach Kidney Care. Reach Kidney Care is a free program that helps with education and planning.
- Registered Renal Dietician
- Renal Social Worker: The process of CKD can be emotional for children and their families. This can be made harder by financial and other burdens. Social work assistance is available and almost universally invaluable. Often children and families benefit from counseling support and the renal social worker can help identify appropriate local resources.