Minimal Change Disease: The Most Steroid-Responsive Kidney Disease

What it is

MCD is a podocyte disease: the filter's foot processes 'melt' (efface), protein floods into urine, but the kidney looks nearly normal under standard microscopy — hence 'minimal change.' A circulating immune factor is believed to drive it (the same factor likely explains its steroid sensitivity).

It's the classic cause of childhood nephrotic syndrome — the child who wakes with puffy eyes and swollen ankles after a cold.

Diagnosis

Presentation: nephrotic-range proteinuria, low albumin, edema — often with a history of a viral infection or immunization days-weeks before. In children with typical presentation, steroids are often started without biopsy; adults usually get a biopsy (to exclude FSGS, membranous, and IgA), and to guide the longer treatment course.

Steroid response itself is diagnostic: dramatic proteinuria fall within weeks confirms MCD.

Treatment and relapses

First-line: prednisone — children ~8 weeks, adults 4-6 months with tapering (the adult course is longer to reduce relapse). ~90% of children and most adults remit.

Relapse is the issue: about half of children relapse at least once; frequent relapsers (2+ in 6 months) or steroid-dependent patients get steroid-sparing agents: calcineurin inhibitors (tacrolimus/cyclosporine), mycophenolate, or rituximab — which has excellent data for steroid-dependent MCD.

Watch for steroid side effects (weight, glucose, mood, growth in children), infections, and — especially in adults — the rare acute kidney injury that MCD can cause.