A child with minimal change disease (MCD) has selective proteinuria of albumin with preserved excretion of IgG. Which ultrastructural glomerular change explains the selective loss of albumin?

• A GBM thickening increasing hydraulic permeability selectively for albumin
• B Mesangial IgA deposits disrupting the filtration slit diaphragm
• C Endothelial fenestrae widening allowing passage of large proteins
• D Effacement of podocyte foot processes reducing the charge barrier ✓

Explanation

MCD is characterised by selective loss of the podocyte negative charge barrier (heparan sulphate proteoglycans on the GBM surface and the glycocalyx of podocyte foot processes) and effacement (fusion) of foot processes on electron microscopy. Because albumin (MW ~69 kDa, anionic) normally faces charge repulsion from the anionic GBM, loss of the charge barrier preferentially allows albumin through while retaining larger anionic proteins like IgG, explaining selectivity. There are no immune deposits and no GBM thickening in MCD.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.