Definition

Minimal Change Disease is a subtype of nephrotic syndrome (a kidney disorder) that is most commonly seen in children but is occasionally present in adults.

Description

Nephrotic syndrome (nephrosis) is a symptom complex seen in patients with various forms of glomerular diseases (glomeruli are tiny structures in the kidney that filter waste products from the blood). It is characterized by an increase in capillary wall permeability (leakiness) to serum protein in association with excretion of large amounts of protein in the urine, low albumin levels in the blood, edema (swelling), and hyperlipidemia (high lipid or fat levels in the blood).

The kidney's filtering membrane is constructed like a sieve that allows small molecules to pass through the blood but retains the larger protein molecules. In nephrotic syndrome (nephrosis), the membrane is damaged by another illness, such as diabetes, or an injury, and large amounts of these proteins suddenly leak from the blood into the urine. Within a few days, the blood proteins are markedly depleted. The flow back to the blood of normal tissue fluid is also impaired, leading to tissue swelling (edema).

Minimal change disease (MCD) is a subtype of nephrotic syndrome and accounts for about 20 percent of cases of nephrotic syndrome in adults.

Causes and Risk Factors

MCD is most common in young children. It can be idiopathic (cause unknown) but also occurs after viral upper respiratory infections, in association with tumors such as Hodgkin's disease, and with hypersensitivity reactions (e.g., non-steroidal anti-inflammatory drugs [NSAIDs] and bee stings).

Symptoms

Edema (swelling) occurs, especially in the lower legs and lower back. Other symptoms include shortness of breath and abdominal fullness due to ascites (fluid in the abdomen). Patients are more susceptible to infection as well.

Diagnosis

Diagnosis is based on the medical history including symptoms, physical examination, blood tests (especially albumin and lipids), and urine tests (for protein).

Treatment

Identifiable causative diseases must be treated. Additional treatment is with corticosteroids (prednisone). Response is excellent for most patients but about 10 percent of patients become steroid-unresponsive after 4 to 6 weeks.

Patients with frequent relapses and steroid resistance may benefit from cyclophosphamide and chlorambucil. Bed rest may be indicated for patients with severe edema or those who have infections. Hospitalization may be necessary when corticosteroid therapy is initiated. Dietary recommendations may be made in consultation with a nutritionist.

Questions to Ask Your Doctor

• Is it minimal change disease?
• Is there an underlying disease causing this?
• What are treatment options?
• Will you prescribe corticosteroids?
• What are the side effects?
• What is the prognosis?