Minimal Change Disease
Description of the Disease
Minimal change disease is a kidney disorder that is the most common cause of nephrotic syndrome in children. Nephrotic syndrome is characterized by excessive protein loss in the urine (more than 3.5 g per day), low blood albumin levels (hypoalbuminemia), and generalized edema, particularly affecting the face, legs, and areas around the eyes.
Minimal change disease most commonly affects children between 2 and 3 years of age, although it can also occur in adults.
Cause of the Disease
The exact cause of minimal change disease is unknown. In some cases, it may develop after the use of certain medications or in association with hematologic malignancies. The condition is named “minimal change disease” because kidney tissue appears essentially normal under a light microscope. However, characteristic abnormalities of the podocytes (specialized cells of the kidney’s filtering units) can be detected using electron microscopy.
Symptoms
The hallmark symptom is the sudden onset of swelling (edema), which typically develops over several days. Edema most commonly affects the face, hands, feet, ankles, and areas around the eyes, but it may become generalized.
The swollen areas are usually painless, although swelling of the legs or abdomen may cause discomfort or a feeling of heaviness. The edema results from fluid retention caused by excessive loss of protein in the urine.
Because edema is also a feature of other conditions, such as heart or liver disease, additional diagnostic tests are necessary to establish the correct diagnosis.
Diagnosis
In children, the diagnosis is often based on the presence of nephrotic syndrome, particularly marked proteinuria detected on urinalysis. In atypical or uncertain cases, a kidney biopsy may be performed.
On light microscopy, kidney tissue appears normal or shows only minimal abnormalities. Electron microscopy reveals the characteristic finding of widespread fusion (effacement) of the podocyte foot processes, confirming the diagnosis.
Treatment
Minimal change disease is primarily treated with glucocorticosteroids, which are highly effective in most patients. Treatment usually continues for several months, and kidney function and protein loss often return to normal.
Relapses are common, particularly in children. In patients with frequent relapses or steroid-resistant disease, additional immunosuppressive medications, including cytotoxic agents or other steroid-sparing therapies, may be required.
Source | Author Doctor Nikas Samuolis, reviewed by Prof. Virginijus Šapoka | Vilnius University | Faculty of Medicine | Head of the Department of Internal Medicine, Family Medicine, and Oncology