Thin basement membrane disease diagnostic study of choice

Renal biopsy is the gold standard test for TBMD. The WHO guideline for normal GBM thickness is 250nm for adult and 180nm for children of 2-11 years of age. Diffuse thinning of 50% of glomerular basement membrane in glomerular capillaries is the criteria for diagnosing TBMD on Electron microscopy.

The following result of Renal biopsy is confirmatory of TBMD:

• Light microscopy of renal samples shows usually normal glomerular histopathology with minimally showing nonspecific findings including matrix expansion, mesangial cellular proferation, RBCs in glomerular spaces with focal segmental glomerulosclerosis or fibrosis on rare occasions.^[1]
• Electron microscopy of renal samples shows diffuse thinning of 50% of glomerular basement membrane in glomerular capillaries. GBM thickness should be measured according to age.The WHO guideline for normal GBM thickness is 250nm for adult and 180nm for children of 2-11 years of age. ^[2] Early stages of X-linked alport syndrome is similar to TBMD, so differential features including lamellation/thickening must be ruled out on electron microscopy. ^[3]
• Immunohistochemistry of renal samples evaluates Type 4 collagen alpha 3-alpha5 chains to differentiate TBMD and early stage of alport syndrome.^[4]
• Absence of any other gross Glomerular pathology.

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