What Is Nephrotic Syndrome?
Nephrotic syndrome is a group of symptoms that includes the following:
- Low levels of protein in the blood
- Swelling of tissue (edema), especially around the eyes, and in the feet, and hands
- High levels of cholesterol in the blood
Nephrotic syndrome is caused by a variety of diseases and underlying disorders that damage the kidneys, resulting in excessive excretion of protein in the urine. Some kidney diseases that cause too much protein in your urine are called:
- Membranous Nephropathy (MN)
- Focal Segmental Glomerulosclerosis (FSGS)
- Minimal Change Disease (MCD)
- Membranoproliferative Glomerulonephritis (MPGN)
- Lupus Nephritis
- IgA Nephropathy
These diseases damage the glomeruli, which are small blood vessels that filter wastes and excess water from the blood and pass them into the bladder as urine.
As a result of protein loss in the urine, the blood is deficient in protein. Normal amounts of blood protein are needed to help regulate fluid pressure throughout the body. Protein in the blood normally draws water from the tissues into the bloodstream. When blood protein levels are low, the normal movement of water is reversed, and fluid is drawn from the blood and accumulates in the tissues. This excess tissue fluid causes the swelling and puffiness (edema) that is a symptom of nephrotic syndrome.
Nephrotic Syndrome Symptoms
You should be evaluated by a doctor if you experience any of the following signs or symptoms of nephrotic syndrome:
- Foam in the toilet water when you urinate. This may be caused by excess protein in your urine, a sign of nephrotic syndrome.
- Swelling (edema), particularly around your eyes or in the ankles and feet. This can result from kidney damage that results in leakage of protein into the urine. The resulting loss of protein from the blood can result in fluid retention in the tissues.
- Weight gain. The retention of excess fluid in your body due to nephrotic syndrome can lead to weight gain. If your stomach and intestines are affected, edema also can cause loss of appetite and vomiting.
How Is Nephrotic Syndrome Diagnosed?
Diagnosis of nephrotic syndrome requires blood and urine samples. A high level of protein in a single urine sample may indicate nephrotic syndrome. The doctor may order a 24-hour collection of urine in order to get a more precise measurement of how much protein is being passed by the kidneys.
Blood tests may show low levels of protein. If kidney damage is advanced, waste products such as creatinine and urea that are normally filtered from the blood into the urine by the kidney may accumulate in the blood.
Once nephrotic syndrome is diagnosed, the doctor may recommend a kidney biopsy, a procedure in which tiny pieces of the kidney are removed for examination. The biopsy may reveal the underlying disease so that the doctor can determine a course of treatment. Nephrotic syndrome is frequently seen in patients with diabetes. If a person has had diabetes for some time, and the patient history and laboratory tests are consistent with diabetes as the cause of nephrotic syndrome, a biopsy is normally not taken.