Minimal change disease (also known as MCD, minimal change glomerulopathy, and nil disease, among others) is a disease affecting the kidneys which causes a nephrotic syndrome. Nephrotic syndrome leads to the loss of significant amounts of protein in the urine, which causes the widespread edema (soft tissue swelling) and impaired kidney function commonly experienced by those affected by the disease. It is most common in children and has a peak incidence at 2 to 6 years of age. MCD is responsible for 10–25% of nephrotic syndrome cases in adults. It is also the most common cause of nephrotic syndrome of unclear cause (idiopathic) in children. Signs and symptoms
The clinical signs of minimal change disease are proteinuria (abnormal excretion of proteins, mainly albumin, into the urine), edema (swelling of soft tissues as a consequence of water retention),  weight gain, and hypoalbuminaemia (low serum albumin). These signs are referred to collectively as nephrotic syndrome. The first clinical sign of minimal change disease is usually edema with an associated increase in weight. The swelling may be mild but patients can present with edema in the lower half of the body, periorbital edema, swelling in the scrotal/labial area and anasarca in more severe cases. In older adults, patients may also present with acute kidney injury (20–25% of affected adults) and high blood pressure. Due to the disease process, patients with minimal change disease are also at risk of blood clots and infections.
Initial workup can include a urinalysis, kidney function tests, serum albumin level and a lipid panel. Microscopic amounts of blood are present in the urine of 10-30% adults with MCD.As MCD is the most common type of nephrotic syndrome in children, renal biopsy is not usually done in children under the age of 10 unless there are concerning features that are unusual for the disease (high blood pressure, bloody urine, renal dysfunction) and if they fail to respond to corticosteroid therapy. These would suggest that it may not be minimal change disease. In adults, a renal biopsy is required as there is a much wider differential for nephrotic syndrome. As the name suggests, the renal biopsy of a patient with minimal change disease would show minimal or no evidence of disease in light microscopy, which is unique among the causes of nephrotic syndrome. Treatment
Children
The first line therapy to minimal change disease is corticosteroids T.Prednisolone 60mg/sq.m/day or 2mg/kg/day. For those are who are unable to tolerate corticosteroid treatment, cyclosporine is an alternative; other immunosuppressants have also been used such as calcineurin inhibitor, mycophenolate mofetil, rituximab though studies on their effectiveness is fairly limited. There is no common consensus on how long the corticosteroid therapy should be, with treatment length ranging from 4–12 weeks. Along with corticosteroid therapy, acute symptomatic management involves salt and fluid restriction to control the swelling.For children who do not respond to corticosteroids (usually after a trial of 8 weeks), cyclosporine can be tried.