Lab Tests Your Child Will Have While On Dialysis

Your child will have blood tests monthly or more often, if needed. The blood tests are used to find out how well the dialysis treatment is working and your child’s overall health.

Blood urea nitrogen (BUN) is a waste product released by the kidney and removed by dialysis. This number should be less than 90. If the BUN is higher than 90 the kidney nutritionist will talk to you about lowering the amount of protein in your child’s diet.

The BUN is measured before and after a dialysis. The number is placed in a formula that shows how well the dialysis treatment is working. This is called dialysis adequacy. The dialysis adequacy value should be 1.4 or greater. Values lower than 1.4 are linked with poorer health. If your child’s adequacy value is lower than 1.4, we will adjust their dialysis treatment.

Creatinine is a waste product removed by the kidney. It is not affected by your diet like the BUN. This number should be below 13.

Potassium is used for muscle function. A potassium level of 3.5 to 4.5 is best. If the level is too high muscles will not work well and your child may feel weak. High potassium levels can also affect the heart muscle, therefore having a high level can be dangerous. Sometimes, if a level becomes too high, a person may require medicine or an extra dialysis treatment to bring the level down. Potassium is removed by dialysis, but your child still needs to limit high potassium foods between treatments. See the nutrition section of the dialysis packet for more information.

Calcium is needed in the body for bone building and muscle function. Calcium will go lower when the phosphorus level is high (see below). Without calcium the bones become brittle which may not be reversible. This may lead to bone deformities, poor growth and random bone fractures (not due to trauma). A calcium level between 9 and 10 is the goal.

Dialysis only removes only a small amount of phosphorus from your blood. When phosphorus levels become too high, the calcium becomes low. Phosphorus levels should be 4.5 to 5.5. Taking phosphorus binders as prescribed and limiting phosphorus foods is the best way to keep your child’s calcium and phosphorus in balance. This will keep your child’s bones healthy.

When calcium levels become too low the Parathyroid gland tries to raise them by releasing parathyroid hormone (PTH). The PTH pulls calcium out of the bone which causes brittle bones. The PTH should be in the low 100s but the exact range depends on your child’s age and needs. Your child’s doctor will prescribe vitamin D to be given with dialysis and/or to be taken as a pill. The vitamin D helps to keep the PTH level down. See the medicine section of the dialysis packet for more information on vitamin D.

Hemoglobin (Hgb) is made up of iron and protein. It is the part of the red blood cell that holds onto oxygen when the red blood cell moves the oxygen from the lungs to different parts of the body. The body needs the hormone erythropoietin (EPO) and iron to make enough red blood cells with healthy Hgb. Kidneys that do not work cannot release the EPO. This means that erythropoietin stimulating hormone (ESA) must be given by IV or subcutaneously (by injection) to your child while on dialysis. The dose of ESA is adjusted to keep the Hgb between 11 and 13.

See the medicine section of the dialysis packet for more information on ESA.