Minimal change disease is a kidney disorder primarily affecting children that leads to nephrotic syndrome, characterized by symptoms like protein in urine, swelling, and high cholesterol levels. The condition results from damage to the glomeruli in nephrons and is often treated with corticosteroids, while diagnostic tests include urine and blood tests as well as potential kidney biopsy. Most patients recover without long-term kidney failure, although relapses can occur and may require additional treatment.