Minimal change disease is a kidney disorder. Each kidney is made of more than a million units called nephrons. Each nephron has a tuft of blood vessels called a glomerulus, which is surrounded by a structure called the Bowman's Capsule. Together, these structures filter blood and produce urine.

Minimal change disease is one cause of nephrotic syndrome. It is named "minimal change" because the nephrons appear totally normal under a light (regular) microscope. The condition is only seen using an electron microscope, which reveals changes in the glomeruli. Urine tests also show high protein levels.

Minimal change disease is the most common cause of nephrotic syndrome in children. It is also frequently seen in adults. The cause is unknown, but the disease may be preceded by viral infection, allergic reactions, or recent immunizations.

Minimal change disease does not reduce the amount of urine produced. It rarely progresses to kidney failure.

There may be symptoms of nephrotic syndrome:

• swelling -- especially around the eyes, feet and ankles, and in the abdomen
• foamy appearance of the urine
• weight gain (from fluid retention)
• poor appetite

The doctor would not be able to see any obvious outward signs of the disease, other than swelling. But blood tests and urinalysis would reveal results typical of nephrotic syndrome, including high levels of urine protein, low blood albumin levels, and high cholesterol.

A kidney biopsy and examination of the tissue with an electron microscope would show the classic changes of minimal change disease. An immunofluorescence exam of biopsied kidney tissue is negative.