Each kidney is made of more than a million units called nephrons, which filter blood and produce urine.
In minimal change disease, there is damage to the glomeruli -- the tiny blood vessels inside the nephron where blood is filtered to make urine and waste is removed. The disease gets its name because this damage is not visible under a regular microscope. It can only be seen under an electron microscope.
Minimal change disease is the most common cause of nephrotic syndrome in children. It causes about 80% of cases in young children. It is also seen in adults, but makes up only 10 to 15% of nephrotic syndrome cases.
The cause is unknown, but the disease may occur after or be related to:
There may be symptoms of nephrotic syndrome:
Foamy appearance of the urine
Swelling (especially around the eyes, feet, and ankles, and in the abdomen)
Weight gain (from fluid retention)
Minimal change disease does not reduce the amount of urine produced. It rarely progresses to kidney failure.
Signs and tests
The doctor may not be able to see any signs of the disease, other than swelling. Blood and urine tests reveal signs of nephrotic syndrome, including:
High levels of protein in the urine
Low levels of albumin in the blood
A kidney biopsy and examination of the tissue with an electron microscope can show signs of minimal change disease. An immunofluorescence exam of the biopsied kidney tissue will be negative.
Corticosteroids can cure minimal change disease in most children. Some patients may need to stay on steroids to keep the disease in remission.
Adults do not respond to steroids as well as children, but many still find steroids effective. Adults may have more frequent relapses and become dependent on steroids.
Patients who have three or more relapses may do better with cytotoxic therapy instead of steroids. In most cases, this involves a medication called cyclophosphamide. Other medicines that have been used include cyclosporine and chlorambucil.
Swelling may be treated with:
ACE inhibitor medicines
Blood pressure control
Diuretics (water pills)
You may also be told to reduce the amount of salt in your diet.
Children with minimal change disease usually respond better to corticosteroids than adults. Children often respond within the first month.
A relapse can occur. However, patients may improve after long-term treatment with corticosteroids and medications that suppress the immune system (immunosuppressive medications).
Pais P, Avner ED. Nephrotic syndrome. In: Kliegman RM, Stanton BF, St. Geme JW III, Schor NF, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 521.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Herbert Y. Lin, MD, PHD, Nephrologist, Massachusetts General Hospital; Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.