Data from a longitudinal study (Nephrotic Syndrome Study Network – NEPTUNE) published in 2022 suggested that up to 29% of biopsy-confirmed,  mixed pediatric and adult minimal change disease cases exhibited serum autoantibodies against nephrin, a structural protein located in the podocyte slit diaphragm.There has been discussion of B cell involvement in nephrotic syndrome, especially minimal change disease due to the success of immunotherapy that target both B and T cells, increased markers for B cell activation during a relapse of minimal change disease, and alterations in B cell sub-classes during minimal change disease remission. This hypothesis is supported by recent findings of anti-nephrin antibodies isolated in minimal change disease. Edema
When albumin is excreted in the urine, its serum (blood) concentration decreases. Consequently, the plasma oncotic pressure reduces relative to the interstitial tissue. The subsequent movement of fluid from the vascular compartment to the interstitial compartment manifests as the soft tissue swelling referred to as edema. This fluid collects most commonly in the feet and legs, in response to gravity, particularly in those with poorly functioning valves. In severe cases, fluid can shift into the peritoneal cavity (abdomen) and cause ascites. As a result of the excess fluid, individuals with minimal change disease often gain weight, as they are excreting less water in the urine, and experience fatigue. Diagnosis
As minimal change disease is a subset of nephrotic syndrome, diagnosis involves looking for a combination of edema, high amounts of protein in urine, low albumin and high serum cholesterol.
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.