Chapter 18 - Minimal Change Disease

Abstract

Minimal change disease (MCD) is a common cause of nephrotic syndrome (NS). Although MCD is defined by minor changes on light microscopy and the presence of foot process effacement on electron microscopy, it can be diagnosed clinically by exhibiting responsiveness to corticosteroid treatment. In children, MCD is the cause of up to 90% of cases of idiopathic NS in contrast to adults where it is observed in 10%-15% of patients with new-onset disease. The pathogenesis of MCD is not well understood, but likely represents a variable interaction between intrinsic glomerular podocyte defects and immunologic disturbances. MCD presents with nephrotic-range proteinuria, edema, hypoalbuminemia, and hypercholesterolemia. A hypercoagulable state secondary to the NS is much more common in adult versus pediatric patients. Corticosteroids represent the time-honored initial therapy for presumed and biopsy-confirmed MCD and are effective in 60%-90% of patients depending on age. Second-line immunosuppressive therapy, including calcineurin inhibitors, mycophenolate mofetil, and rituximab, is used in patients with frequently relapsing and steroid-dependent MCD, as well as those who experience, or are at risk from, steroid-related side effects. Recent interventional trials aim to improve clinical and patient-reported outcomes in patients with MCD. Supportive care involves diet and diuretics to control edema, use of lipid-lowering drugs, and immunizations to prevent infection. The long-term prognosis of MCD is excellent with eventual resolution of the disease without any permanent kidney injury. Future research is needed to better define the cause of MCD with the development of more targeted treatments that can effectively achieve long-term remission without the side effects associated with current therapeutic options.