A child with the nephrotic syndrome has these signs:
- High levels of protein in the urine
- Low levels of protein in the blood
- Swelling resulting from buildup of salt and water.
The kidneys are two bean-shaped organs found in the lower back. They are about the size of a fist. They clean the blood by filtering out excess water and salt and waste products from food. Healthy kidneys keep protein in the blood, which helps the blood soak up water from tissues. But kidneys with damaged filters may let protein leak into the urine. As a result, not enough protein is left in the blood to soak up the water. The water then moves from the blood into body tissues and causes swelling. You may see swelling around your child's eyes, belly, and legs. Your child may urinate less often than usual and may gain weight from the excess water.
To diagnose childhood nephrotic syndrome, the doctor may ask for a urine sample to check for protein. The doctor will dip a strip of chemically treated paper into the urine sample.
Too much protein in the urine will make the paper change color. Or the doctor may ask for a 24-hour collection of urine for a more precise measurement of the protein and other substances in the urine.
The doctor may take a blood sample to see how well the kidneys are removing wastes. Healthy kidneys remove creatinine and urea nitrogen from the blood. If the blood contains high levels of these waste products, some kidney damage may have already occurred. But most children with the nephrotic syndrome do not have permanent kidney damage.
In some cases, the doctor may want to examine a small piece of the child's kidney under a microscope to see if substances there are causing the syndrome. The procedure of collecting a small tissue sample from the kidney is called a biopsy, and it is usually performed with a long needle passed through the skin. The child will be awake during the procedure and receive calming drugs and a local painkiller at the site of the needle entry. General anesthesia is used in the very rare cases where open surgery is required. The child will stay overnight in the hospital to rest and allow the health care team to ensure that no problems occur.