The doctor will dip a strip of chemically treated paper into the urine sample. A strip of chemically treated paper will change color when dipped in urine with too much protein. 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.