Minimal change nephrotic syndrome (MCNS) is the main cause of primary nephrotic syndrome in childhood, accounting for approximately 90% of cases. With increasing age MCNS becomes less common and histological pictures associated with steroid-resistance, such as focal segmental glomeruloslerosis, become more common.
The underlying cause for this condition are poorly understood. It is thought to be driven primarily by T lymphocytes which in turn produce cytokines ("glomerular permeability factors") which disrupt the glomerular basement membrane, specifically the charge-selective characteristics.
An important feature of MCNS is that it is usually responsive to steroids.