Growth Failure in Children with Kidney Disease

The kidneys play an important role in a child's growth. In addition to cleaning waste and extra fluid from the blood, the kidneys produce hormones that help with red blood cell production. The kidneys also help regulate the amounts and interactions of nutrients, including minerals like calcium, phosphorus, and vitamin D, necessary for growth. Last, the kidneys may also play a role in the metabolism of growth hormone (somatotropin).

The kidneys activate vitamin D so that it promotes the absorption of calcium from food into the intestines. This vitamin D hormone also helps bones absorb the right amount of calcium. Calcium and vitamin D are essential elements for the normal growth of bones.

If the kidneys are impaired, bones do not get enough calcium to grow. One reason is that the production of the vitamin D hormone may be deficient. Impaired kidneys may also let too much phosphorus build up in the blood; consequently, phosphorus keeps calcium from getting to the bones.

The child's doctor may recommend diet changes and food supplements to treat growth failure. Diet changes may include limiting foods that contain large amounts of phosphorus, like milk and other dairy products (except cream cheese and cottage cheese), meat, fish and poultry. High-phosphorus foods also include some vegetables like broccoli, peas and beans. Dark breads (e.g., whole wheat, pumpernickel) and many cereals are also high in phosphorus. Since it is impossible to avoid all of these foods, it is necessary for caregivers to work with a dietitian to find a healthy way to limit the phosphorus in the child's diet while maintaining a desirable intake of calories and other nutrients necessary to maintain growth and a healthy general condition.

In addition to limiting phosphorus in the child's diet, the doctor may recommend a phosphate binder. This type of medicine keeps phosphorus in the bowel so that it does not stop calcium from getting to the child's bones. The phosphorus is then excreted with the child's bowel movements. Phosphate binders include chewable tablets that are also used as antacids (such as Tums). The child should take the phosphate binder with meals and only according to the doctor's recommendations.

Doctors often recommend calcium supplements for children with kidney disease. (These may be used either as a phosphate binder or to increase the calcium in the child's system. If the calcium supplement is to be used as a phosphate binder, it should be taken with meals. It will not provide extra calcium if used in this way.) If the calcium supplement is intended to provide extra calcium, it should be taken at least an hour after meals so that it is not absorbed by the food.

Another kind of necessary supplement in the management of children with chronic renal disease is the vitamin D hormone. There are different types of vitamin D, and these could be either DHT, calcitriol, or calcifediol. These supplements help the bones absorb calcium and therefore maintain a healthier structure and help somehow in the growth process.

If the child is very short for his or her age as the result of kidney disease, the doctor may consider prescribing human growth hormone; this is injected under the skin. Some questions remain about the usefulness and safety of using growth hormone in kidney patients. Some studies suggest that growth hormone stimulates growth in children with chronic renal conditions or children undergoing maintenance dialysis treatment or transplantation. Other studies indicate that growth hormone may increase the chance for rejection of a transplanted kidney. Another set of studies suggests that use of growth hormone may help treat malnutrition both in children and in adult dialysis patients.

Information provided by the National Institutes of Health

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.