Diagnosis of Nephrotic Syndrome
Nephrotic syndrome is diagnosed when large amounts of protein are found in the urine. The blood protein albumin makes up much of the protein that is lost, though many other important proteins are also lost in nephrotic syndrome.

The presence of albumin in the urine can be detected with a dipstick test performed on a urine sample. The urine sample is collected in a special container in a health care provider’s office or commercial facility and can be tested in the same location or sent to a lab for analysis. For the test, a nurse or technician places a strip of chemically treated paper, called a dipstick, into the urine. Patches on the dipstick change color when protein is present in urine.

A more precise measurement is usually needed to confirm the diagnosis. Either a single urine sample or a 24-hour collection of urine can be sent to a lab for analysis. With the single urine sample, the lab measures both albumin and creatinine, a waste product of normal muscle breakdown. The comparison of the measurements is called a urine albumin-to-creatinine ratio. A urine sample containing more than 30 milligrams of albumin for each gram of creatinine may signal a problem. With a 24-hour collection of urine, the lab measures only the amount of albumin present. The single urine sample is easier to collect than the 24-hour sample and is usually sufficient to confirm diagnosis, though the 24-hour collection may be used in some cases.

Once nephrotic syndrome is diagnosed, blood tests are usually needed to check for systemic diseases that may be causing the nephrotic syndrome and to find out how well the kidneys are working overall. A blood test involves drawing blood at a health care provider’s office or commercial facility and sending the sample to a lab for analysis.

Though blood tests can point toward systemic diseases, a kidney biopsy is usually needed to diagnose the specific underlying disease causing the nephrotic syndrome and to determine the best treatment. A kidney biopsy is a procedure that involves taking a piece of kidney tissue for examination with a microscope. Kidney biopsies are performed by a health care provider in a hospital with light sedation and local anesthetic. A biopsy is often not needed for a person with diabetes because the person’s medical history and lab tests may be enough to diagnose the problem as being a result of diabetes.